Advanced Persistent Threat Compromise of Government Agencies, Critical Infrastructure, and Private Sector Organizations

This Alert uses the MITRE Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK®) version 8 framework. See the ATT&CK for Enterprise version 8 for all referenced threat actor tactics and techniques.

The Cybersecurity and Infrastructure Security Agency (CISA) is aware of compromises of U.S. government agencies, critical infrastructure entities, and private sector organizations by an advanced persistent threat (APT) actor beginning in at least March 2020. This APT actor has demonstrated patience, operational security, and complex tradecraft in these intrusions. CISA expects that removing this threat actor from compromised environments will be highly complex and challenging for organizations.

One of the initial access vectors for this activity is a supply chain compromise of the following SolarWinds Orion products (see Appendix A).

  • Orion Platform 2019.4 HF5, version 2019.4.5200.9083
  • Orion Platform 2020.2 RC1, version 2020.2.100.12219
  • Orion Platform 2020.2 RC2, version 2020.2.5200.12394
  • Orion Platform 2020.2, 2020.2 HF1, version 2020.2.5300.12432

Note: CISA has evidence of additional initial access vectors, other than the SolarWinds Orion platform; however, these are still being investigated. CISA will update this Alert as new information becomes available.

On December 13, 2020, CISA released Emergency Directive 21-01: Mitigate SolarWinds Orion Code Compromise, ordering federal civilian executive branch departments and agencies to disconnect affected devices. Note: this Activity Alert does not supersede the requirements of Emergency Directive 21-01 (ED-21-01) and does not represent formal guidance to federal agencies under ED 21-01.

CISA has determined that this threat poses a grave risk to the Federal Government and state, local, tribal, and territorial governments as well as critical infrastructure entities and other private sector organizations. CISA advises stakeholders to read this Alert and review the enclosed indicators (see Appendix B).

Key Takeaways

  • This is a patient, well-resourced, and focused adversary that has sustained long duration activity on victim networks.
  • The SolarWinds Orion supply chain compromise is not the only initial infection vector this APT actor leveraged.
  • Not all organizations that have the backdoor delivered through SolarWinds Orion have been targeted by the adversary with follow-on actions.
  • Organizations with suspected compromises need to be highly conscious of operational security, including when engaging in incident response activities and planning and implementing remediation plans. 

Click here for a PDF version of this report.


CISA is aware of compromises, which began at least as early as March 2020, at U.S. government agencies, critical infrastructure entities, and private sector organizations by an APT actor. This threat actor has demonstrated sophistication and complex tradecraft in these intrusions. CISA expects that removing the threat actor from compromised environments will be highly complex and challenging. This adversary has demonstrated an ability to exploit software supply chains and shown significant knowledge of Windows networks. It is likely that the adversary has additional initial access vectors and tactics, techniques, and procedures (TTPs) that have not yet been discovered. CISA will continue to update this Alert and the corresponding indicators of compromise (IOCs) as new information becomes available.

Initial Infection Vectors [TA0001]

CISA is investigating incidents that exhibit adversary TTPs consistent with this activity, including some where victims either do not leverage SolarWinds Orion or where SolarWinds Orion was present but where there was no SolarWinds exploitation activity observed. Volexity has also reported publicly that they observed the APT using a secret key that the APT previously stole in order to generate a cookie to bypass the Duo multi-factor authentication protecting access to Outlook Web App (OWA).[1] Volexity attributes this intrusion to the same activity as the SolarWinds Orion supply chain compromise, and the TTPs are consistent between the two. This observation indicates that there are other initial access vectors beyond SolarWinds Orion, and there may still be others that are not yet known.

SolarWinds Orion Supply Chain Compromise

SolarWinds Orion is an enterprise network management software suite that includes performance and application monitoring and network configuration management along with several different types of analyzing tools. SolarWinds Orion is used to monitor and manage on-premise and hosted infrastructures. To provide SolarWinds Orion with the necessary visibility into this diverse set of technologies, it is common for network administrators to configure SolarWinds Orion with pervasive privileges, making it a valuable target for adversary activity.

The threat actor has been observed leveraging a software supply chain compromise of SolarWinds Orion products[2] (see Appendix A). The adversary added a malicious version of the binary solarwinds.orion.core.businesslayer.dll into the SolarWinds software lifecycle, which was then signed by the legitimate SolarWinds code signing certificate. This binary, once installed, calls out to a victim-specific avsvmcloud[.]com domain using a protocol designed to mimic legitimate SolarWinds protocol traffic. After the initial check-in, the adversary can use the Domain Name System (DNS) response to selectively send back new domains or IP addresses for interactive command and control (C2) traffic. Consequently, entities that observe traffic from their SolarWinds Orion devices to avsvmcloud[.]com should not immediately conclude that the adversary leveraged the SolarWinds Orion backdoor. Instead, additional investigation is needed into whether the SolarWinds Orion device engaged in further unexplained communications. If additional Canonical Name record (CNAME) resolutions associated with the avsvmcloud[.]com domain are observed, possible additional adversary action leveraging the back door has occurred.

Based on coordinated actions by multiple private sector partners, as of December 15, 2020, avsvmcloud[.]com resolves to 20.140.0[.]1, which is an IP address on the Microsoft blocklist. This negates any future use of the implants and would have caused communications with this domain to cease. In the case of infections where the attacker has already moved C2 past the initial beacon, infection will likely continue notwithstanding this action.

SolarWinds Orion typically leverages a significant number of highly privileged accounts and access to perform normal business functions. Successful compromise of one of these systems can therefore enable further action and privileges in any environment where these accounts are trusted.

Anti-Forensic Techniques

The adversary is making extensive use of obfuscation to hide their C2 communications. The adversary is using virtual private servers (VPSs), often with IP addresses in the home country of the victim, for most communications to hide their activity among legitimate user traffic. The attackers also frequently rotate their “last mile” IP addresses to different endpoints to obscure their activity and avoid detection.

FireEye has reported that the adversary is using steganography (Obfuscated Files or Information: Steganography [T1027.003]) to obscure C2 communications.[3] This technique negates many common defensive capabilities in detecting the activity. Note: CISA has not yet been able to independently confirm the adversary’s use of this technique.

According to FireEye, the malware also checks for a list of hard-coded IPv4 and IPv6 addresses—including RFC-reserved IPv4 and IPv6 IP—in an attempt to detect if the malware is executed in an analysis environment (e.g., a malware analysis sandbox); if so, the malware will stop further execution. Additionally, FireEye analysis identified that the backdoor implemented time threshold checks to ensure that there are unpredictable delays between C2 communication attempts, further frustrating traditional network-based analysis.

While not a full anti-forensic technique, the adversary is heavily leveraging compromised or spoofed tokens for accounts for lateral movement. This will frustrate commonly used detection techniques in many environments. Since valid, but unauthorized, security tokens and accounts are utilized, detecting this activity will require the maturity to identify actions that are outside of a user’s normal duties. For example, it is unlikely that an account associated with the HR department would need to access the cyber threat intelligence database.

Taken together, these observed techniques indicate an adversary who is skilled, stealthy with operational security, and is willing to expend significant resources to maintain covert presence.

Privilege Escalation and Persistence [TA0004, TA0003]

The adversary has been observed using multiple persistence mechanisms across a variety of intrusions. CISA has observed the threat actor adding authentication tokens and credentials to highly privileged Active Directory domain accounts as a persistence and escalation mechanism. In many instances, the tokens enable access to both on-premise and hosted resources. Microsoft has released a query that can help detect this activity.[4]

Microsoft reported that the actor has added new federation trusts to existing infrastructure, a technique that CISA believes was utilized by a threat actor in an incident to which CISA has responded. Where this technique is used, it is possible that authentication can occur outside of an organization’s known infrastructure and may not be visible to the legitimate system owner. Microsoft has released a query to help identify this activity.[5]

User Impersonation

The adversary’s initial objectives, as understood today, appear to be to collect information from victim environments. One of the principal ways the adversary is accomplishing this objective is by compromising the Security Assertion Markup Language (SAML) signing certificate using their escalated Active Directory privileges. Once this is accomplished, the adversary creates unauthorized but valid tokens and presents them to services that trust SAML tokens from the environment. These tokens can then be used to access resources in hosted environments, such as email, for data exfiltration via authorized application programming interfaces (APIs).

CISA has observed in its incident response work adversaries targeting email accounts belonging to key personnel, including IT and incident response personnel.

These are some key functions and systems that commonly use SAML.

  • Hosted email services
  • Hosted business intelligence applications
  • Travel systems
  • Timecard systems
  • File storage services (such as SharePoint)

Detection: Impossible Logins

The adversary is using a complex network of IP addresses to obscure their activity, which can result in a detection opportunity referred to as “impossible travel.” Impossible travel 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 during the time period between the logins). Note: implementing this detection opportunity can result in false positives if legitimate users apply virtual private network (VPN) solutions before connecting into networks.

Detection: Impossible Tokens

The following conditions may indicate adversary activity.

  • Most organizations have SAML tokens with 1-hour validity periods. Long SAML token validity durations, such as 24 hours, could be unusual.
  • The SAML token contains different timestamps, including the time it was issued and the last time it was used. A token having the same timestamp for when it was issued and when it was used is not indicative of normal user behavior as users tend to use the token within a few seconds but not at the exact same time of issuance.
  • A token that does not have an associated login with its user account within an hour of the token being generated also warrants investigation.

Operational Security

Due to the nature of this pattern of adversary activity—and the targeting of key personnel, incident response staff, and IT email accounts—discussion of findings and mitigations should be considered very sensitive, and should be protected by operational security measures. An operational security plan needs to be developed and socialized, via out-of-band communications, to ensure all staff are aware of the applicable handling caveats.

Operational security plans should include:

  • Out-of-band communications guidance for staff and leadership;
  • An outline of what “normal business” is acceptable to be conducted on the suspect network;
  • A call tree for critical contacts and decision making; and
  • Considerations for external communications to stakeholders and media.

MITRE ATT&CK® Techniques

CISA assesses that the threat actor engaged in the activities described in this Alert uses the below-listed ATT&CK techniques.

  • Query Registry [T1012]
  • Obfuscated Files or Information [T1027]
  • Obfuscated Files or Information: Steganography [T1027.003]
  • Process Discovery [T1057]
  • Indicator Removal on Host: File Deletion [T1070.004]
  • Application Layer Protocol: Web Protocols [T1071.001]
  • Application Layer Protocol: DNS [T1071.004]
  • File and Directory Discovery [T1083]
  • Ingress Tool Transfer [T1105]
  • Data Encoding: Standard Encoding [T1132.001]
  • Supply Chain Compromise: Compromise Software Dependencies and Development Tools [T1195.001]
  • Supply Chain Compromise: Compromise Software Supply Chain [T1195.002]
  • Software Discovery [T1518]
  • Software Discovery: Security Software [T1518.001]
  • Create or Modify System Process: Windows Service [T1543.003]
  • Subvert Trust Controls: Code Signing [T1553.002]
  • Dynamic Resolution: Domain Generation Algorithms [T1568.002]
  • System Services: Service Execution [T1569.002]
  • Compromise Infrastructure [T1584]

SolarWinds Orion Owners

Owners of vulnerable SolarWinds Orion products will generally fall into one of three categories.

  • Category 1 includes those who do not have the identified malicious binary. These owners can patch their systems and resume use as determined by and consistent with their internal risk evaluations.
  • Category 2 includes those who have identified the presence of the malicious binary—with or without beaconing to avsvmcloud[.]com. Owners with malicious binary whose vulnerable appliances only unexplained external communications are with avsvmcloud[.]com—a fact that can be verified by comprehensive network monitoring for the device—can harden the device, re-install the updated software from a verified software supply chain, and resume use as determined by and consistent with a thorough risk evaluation.
  • Category 3 includes those with the binary beaconing to avsvmcloud[.]com and secondary C2 activity to a separate domain or IP address. If you observed communications with avsvmcloud[.]com that appear to suddenly cease prior to December 14, 2020— not due to an action taken by your network defenders—you fall into this category. Assume the environment has been compromised, and initiate incident response procedures immediately.

Compromise Mitigations

If the adversary has compromised administrative level credentials in an environment—or if organizations identify SAML abuse in the environment, simply mitigating individual issues, systems, servers, or specific user accounts will likely not lead to the adversary’s removal from the network. In such cases, organizations should consider the entire identity trust store as compromised. In the event of a total identity compromise, a full reconstitution of identity and trust services is required to successfully remediate. In this reconstitution, it bears repeating that this threat actor is among the most capable, and in many cases, a full rebuild of the environment is the safest action.

SolarWinds Orion Specific Mitigations

The following mitigations apply to networks using the SolarWinds Orion product. This includes any information system that is used by an entity or operated on its behalf.

Organizations that have the expertise to take the actions in Step 1 immediately should do so before proceeding to Step 2. Organizations without this capability should proceed to Step 2. Federal civilian executive branch agencies should ignore the below and refer instead to Emergency Directive 21-01 (and forthcoming associated guidance) for mitigation steps.

  • Step 1
    • Forensically image system memory and/or host operating systems hosting all instances of affected versions of SolarWinds Orion. Analyze for new user or service accounts, privileged or otherwise.
    • Analyze stored network traffic for indications of compromise, including new external DNS domains to which a small number of agency hosts (e.g., SolarWinds systems) have had connections.
  • Step 2
    • Affected organizations should immediately disconnect or power down affected all instances of affected versions of SolarWinds Orion from their network.
    • Additionally:
      • Block all traffic to and from hosts, external to the enterprise, where any version of SolarWinds Orion software has been installed.
      • Identify and remove all threat actor-controlled accounts and identified persistence mechanisms.  
  • Step 3  
    • Only after all known threat actor-controlled accounts and persistence mechanisms have been removed:

See Joint Alert on Technical Approaches to Uncovering and Remediating Malicious Activity for more information on incident investigation and mitigation steps based on best practices.

CISA will update this Alert, as information becomes available and will continue to provide technical assistance, upon request, to affected entities as they work to identify and mitigate potential compromises.


Cyber Actors Target K-12 Distance Learning Education to Cause Disruptions and Steal Data

This Joint Cybersecurity Advisory was coauthored by the Federal Bureau of Investigation (FBI), the Cybersecurity and Infrastructure Security Agency (CISA), and the Multi-State Information Sharing and Analysis Center (MS-ISAC).

The FBI, CISA, and MS-ISAC assess malicious cyber actors are targeting kindergarten through twelfth grade (K-12) educational institutions, leading to ransomware attacks, the theft of data, and the disruption of distance learning services. Cyber actors likely view schools as targets of opportunity, and these types of attacks are expected to continue through the 2020/2021 academic year. These issues will be particularly challenging for K-12 schools that face resource limitations; therefore, educational leadership, information technology personnel, and security personnel will need to balance this risk when determining their cybersecurity investments.

Click here for a PDF version of this report.

As of December 2020, the FBI, CISA, and MS-ISAC continue to receive reports from K-12 educational institutions about the disruption of distance learning efforts by cyber actors.


The FBI, CISA, and MS-ISAC have received numerous reports of ransomware attacks against K-12 educational institutions. In these attacks, malicious cyber actors target school computer systems, slowing access, and—in some instances—rendering the systems inaccessible for basic functions, including distance learning. Adopting tactics previously leveraged against business and industry, ransomware actors have also stolen—and threatened to leak—confidential student data to the public unless institutions pay a ransom.

According to MS-ISAC data, the percentage of reported ransomware incidents against K-12 schools increased at the beginning of the 2020 school year. In August and September, 57% of ransomware incidents reported to the MS-ISAC involved K-12 schools, compared to 28% of all reported ransomware incidents from January through July.

The five most common ransomware variants identified in incidents targeting K-12 schools between January and September 2020—based on open source information as well as victim and third-party incident reports made to MS-ISAC—are Ryuk, Maze, Nefilim, AKO, and Sodinokibi/REvil.


Figure 1 identifies the top 10 malware strains that have affected state, local, tribal, and territorial (SLTT) educational institutions over the past year (up to and including September 2020). Note: These malware variants are purely opportunistic as they not only affect educational institutions but other organizations as well.

ZeuS and Shlayer are among the most prevalent malware affecting K-12 schools.

  • ZeuS is a Trojan with several variants that targets Microsoft Windows operating systems. Cyber actors use ZeuS to infect target machines and send stolen information to command-and-control servers.
  • Shlayer is a Trojan downloader and dropper for MacOS malware. It is primarily distributed through malicious websites, hijacked domains, and malicious advertising posing as a fake Adobe Flash updater. Note: Shlayer is the only malware of the top 10 that targets MacOS; the other 9 affect Microsoft Windows operating systems

Figure 1: Top 10 malware affecting SLTT educational institutions

Distributed Denial-of-Service Attacks

Cyber actors are causing disruptions to K-12 educational institutions—including third-party services supporting distance learning—with distributed denial-of-service (DDoS) attacks,  which temporarily limit or prevent users from conducting daily operations. The availability of DDoS-for-hire services provides opportunities for any motivated malicious cyber actor to conduct disruptive attacks regardless of experience level. Note: DDoS attacks overwhelm servers with a high level of internet traffic originating from many different sources, making it impossible to mitigate at a single source.

Video Conference Disruptions

Numerous reports received by the FBI, CISA, and MS-ISAC since March 2020 indicate uninvited users have disrupted live video-conferenced classroom sessions. These disruptions have included verbally harassing students and teachers, displaying pornography and/or violent images, and doxing meeting attendees (Note: doxing is the act of compiling or publishing personal information about an individual on the internet, typically with malicious intent). To enter classroom sessions, uninvited users have been observed:

  • Using student names to trick hosts into accepting them into class sessions, and
  • Accessing meetings from either publicly available links or links shared with outside users (e.g., students sharing links and/or passwords with friends).

Video conference sessions without proper control measures risk disruption or compromise of classroom conversations and exposure of sensitive information.

Additional Risks and Vulnerabilities

In addition to the recent reporting of distance learning disruptions received by the FBI, CISA, and MS-ISAC, malicious cyber actors are expected to continue seeking opportunities to exploit the evolving remote learning environment.

Social Engineering

Cyber actors could apply social engineering methods against students, parents, faculty, IT personnel, or other individuals involved in distance learning. Tactics, such as phishing, trick victims into revealing personal information (e.g., password or bank account information) or performing a task (e.g., clicking on a link). In such scenarios, a victim could receive what appears to be legitimate email that:

  • Requests personally identifiable information (PII) (e.g., full name, birthdate, student ID),
  • Directs the user to confirm a password or personal identification number (PIN),
  • Instructs the recipient to visit a website that is compromised by the cyber actor, or
  • Contains an attachment with malware.

Cyber actors also register web domains that are similar to legitimate websites in an attempt to capture individuals who mistype URLs or click on similar looking URLs. These types of attacks are referred to as domain spoofing or homograph attacks. For example, a user wanting to access could mistakenly click on (changed “o” to an “e”) or (changed letter “l” to a number “1”) (Note: this is a fictitious example to demonstrate how a user can mistakenly click and access a website without noticing subtle changes in website URLs). Victims believe they are on a legitimate website when, in reality, they are visiting a site controlled by a cyber actor.

Technology Vulnerabilities and Student Data

Whether as collateral for ransomware attacks or to sell on the dark web, cyber actors may seek to exploit the data-rich environment of student information in schools and education technology (edtech) services. The need for schools to rapidly transition to distance learning likely contributed to cybersecurity gaps, leaving schools vulnerable to attack. In addition, educational institutions that have outsourced their distance learning tools may have lost visibility into data security measures. Cyber actors could view the increased reliance on—and sharp usership growth in—these distance learning services and student data as lucrative targets.

Open/Exposed Ports

The FBI, CISA, and MS-ISAC frequently see malicious cyber actors exploiting exposed Remote Desktop Protocol (RDP) services to gain initial access to a network and, often, to manually deploy ransomware. For example, cyber actors will attack ports 445 (Server Message Block [SMB]) and 3389 (RDP) to gain network access. They are then positioned to move laterally throughout a network (often using SMB), escalate privileges, access and exfiltrate sensitive information, harvest credentials, or deploy a wide variety of malware. This popular attack vector allows cyber actors to maintain a low profile, as they are using a legitimate network service that provides them with the same functionality as any other remote user.

End-of-Life Software

End-of-Life (EOL) software is regularly exploited by cyber actors—often to gain initial access, deface websites, or further their reach in a network. Once a product reaches EOL, customers no longer receive security updates, technical support, or bug fixes. Unpatched and vulnerable servers are likely to be exploited by cyber actors, hindering an organization’s operational capacity.

Plans and Policies

The FBI and CISA encourage educational providers to maintain business continuity plans—the practice of executing essential functions through emergencies (e.g., cyberattacks)—to minimize service interruptions. Without planning, provision, and implementation of continuity principles, institutions may be unable to continue teaching and administrative operations. Evaluating continuity and capability will help identify potential operational gaps. Through identifying and addressing these gaps, institutions can establish a viable continuity program that will help keep them functioning during cyberattacks or other emergencies. The FBI and CISA suggest K-12 educational institutions review or establish patching plans, security policies, user agreements, and business continuity plans to ensure they address current threats posed by cyber actors.

Network Best Practices

  • Patch operating systems, software, and firmware as soon as manufacturers release updates.
  • Check configurations for every operating system version for educational institution-owned assets to prevent issues from arising that local users are unable to fix due to having local administration disabled.
  • Regularly change passwords to network systems and accounts and avoid reusing passwords for different accounts.
  • Use multi-factor authentication where possible.
  • Disable unused remote access/RDP ports and monitor remote access/RDP logs.
  • Implement application and remote access allow listing to only allow systems to execute programs known and permitted by the established security policy.
  • Audit user accounts with administrative privileges and configure access controls with least privilege in mind.
  • Audit logs to ensure new accounts are legitimate.
  • Scan for open or listening ports and mediate those that are not needed.
  • Identify critical assets such as student database servers and distance learning infrastructure; create backups of these systems and house the backups offline from the network.
  • Implement network segmentation. Sensitive data should not reside on the same server and network segment as the email environment.
  • Set antivirus and anti-malware solutions to automatically update; conduct regular scans.

User Awareness Best Practices

  • Focus on awareness and training. Because end users are targeted, make employees and students aware of the threats—such as ransomware and phishing scams—and how they are delivered. Additionally, provide users training on information security principles and techniques as well as overall emerging cybersecurity risks and vulnerabilities.
  • Ensure employees know who to contact when they see suspicious activity or when they believe they have been a victim of a cyberattack. This will ensure that the proper established mitigation strategy can be employed quickly and efficiently.
  • Monitor privacy settings and information available on social networking sites.

Ransomware Best Practices

The FBI and CISA do not recommend paying ransoms. Payment does not guarantee files will be recovered. It may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. However, regardless of whether your organization decided to pay the ransom, the FBI urges you to report ransomware incidents to your local FBI field office. Doing so provides the FBI with the critical information they need to prevent future attacks by identifying and tracking ransomware attackers and holding them accountable under U.S. law.

In addition to implementing the above network best practices, the FBI and CISA also recommend the following:

  • Regularly back up data, air gap, and password protect backup copies offline.
  • Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, secure location.

Denial-of-Service Best Practices

  • Consider enrolling in a denial-of-service mitigation service that detects abnormal traffic flows and redirects traffic away from your network.
  • Create a partnership with your local internet service provider (ISP) prior to an event and work with your ISP to control network traffic attacking your network during an event.
  • Configure network firewalls to block unauthorized IP addresses and disable port forwarding.

Video-Conferencing Best Practices

  • Ensure participants use the most updated version of remote access/meeting applications.
  • Require passwords for session access.
  • Encourage students to avoid sharing passwords or meeting codes.
  • Establish a vetting process to identify participants as they arrive, such as a waiting room.
  • Establish policies to require participants to sign in using true names rather than aliases.
  • Ensure only the host controls screensharing privileges.
  • Implement a policy to prevent participants from entering rooms prior to host arrival and to prevent the host from exiting prior to the departure of all participants.

Edtech Implementation Considerations

  • When partnering with third-party and edtech services to support distance learning, educational institutions should consider the following:
  • The service provider’s cybersecurity policies and response plan in the event of a breach and their remediation practices:
    • How did the service provider resolve past cyber incidents? How did their cybersecurity practices change after these incidents?
  • The provider’s data security practices for their products and services (e.g., data encryption in transit and at rest, security audits, security training of staff, audit logs);
  • The provider’s data maintenance and storage practices (e.g., use of company servers, cloud storage, or third-party services);
  • Types of student data the provider collects and tracks (e.g., PII, academic, disciplinary, medical, biometric, IP addresses);
  • Entities to whom the provider will grant access to the student data (e.g., vendors);
  • How the provider will use student data (e.g., will they sell it to—or share it with—third parties for service enhancement, new product development, studies, marketing/advertising?);
  • The provider’s de-identification practices for student data; and
  • The provider’s policies on data retention and deletion.

Malware Defense

Table 1 identifies CISA-created Snort signatures, which have been successfully used to detect and defend against related attacks, for the malware variants listed below. Note: the listing is not fully comprehensive and should not be used at the exclusion of other detection methods.

Table 1: Malware signatures

Malware Signature
NanoCore alert tcp any any -> any $HTTP_PORTS (msg:"NANOCORE:HTTP GET URI contains 'FAD00979338'"; sid:00000000; rev:1; flow:established,to_server; content:"GET"; http_method; content:"getPluginName.php?PluginID=FAD00979338"; fast_pattern; http_uri; classtype:http-uri; metadata:service http;) 


alert tcp any any -> any $HTTP_PORTS (msg:"HTTP Client Header contains 'host|3a 20|'"; sid:00000000; rev:1; flow:established,to_server; flowbits:isnotset,<unique_ID>.tagged; content:"host|3a 20||0d 0a|"; http_header; fast_pattern:only; flowbits:set,<unique_ID>.tagged; tag:session,10,packets; classtype:http-header; metadata:service http;) 
Kovter alert tcp any any -> any $HTTP_PORTS (msg:"Kovter:HTTP URI POST to CnC Server"; sid:00000000; rev:1; flow:established,to_server; flowbits:isnotset,<unique_ID>.tagged; content:"POST / HTTP/1.1"; depth:15; content:"Content-Type|3a 20|application/x-www-form-urlencoded"; http_header; depth:47; fast_pattern; content:"User-Agent|3a 20|Mozilla/"; http_header; content:!"LOADCURRENCY"; nocase; content:!"Accept"; http_header; content:!"Referer|3a|"; http_header; content:!"Cookie|3a|"; nocase; http_header; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/P"; pcre:"/User-Agentx3a[^rn]+rnHostx3ax20(?:d{1,3}.){3}d{1,3}rnContent-Lengthx3ax20[1-5][0-9]{2,3}rn(?:Cache-Control|Pragma)x3a[^rn]+rn(?:rn)?$/H"; flowbits:set,<unique_ID>.tagged; tag:session,10,packets; classtype:nonstd-tcp; metadata:service http;)

alert tcp any any -> any $HTTP_PORTS (msg:"HTTP URI GET contains 'invoice_########.doc' (DRIDEX)"; sid:00000000; rev:1; flow:established,to_server; content:"invoice_"; http_uri; fast_pattern:only; content:".doc"; nocase; distance:8; within:4; content:"GET"; nocase; http_method; classtype:http-uri; metadata:service http;)
alert tcp any any -> any $HTTP_PORTS (msg:"HTTP Client Header contains 'Host|3a 20|tanevengledrep ru' (DRIDEX)"; sid:00000000; rev:1; flow:established,to_server; flowbits:isnotset,<unique_ID>.tagged; content:"Host|3a 20|tanevengledrep|2e|ru|0d 0a|"; http_header; fast_pattern:only; flowbits:set,<unique_ID>.tagged; tag:session,10,packets; classtype:http-header; metadata:service http;)


Advanced Persistent Threat Actors Targeting U.S. Think Tanks

This Advisory uses the MITRE Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK®) framework. See the ATT&CK for Enterprise for all referenced threat actor tactics and techniques.

The Cybersecurity and Infrastructure Security Agency (CISA) and the Federal Bureau of Investigation (FBI) have observed persistent continued cyber intrusions by advanced persistent threat (APT) actors targeting U.S. think tanks. This malicious activity is often, but not exclusively, directed at individuals and organizations that focus on international affairs or national security policy.[1] The following guidance may assist U.S. think tanks in developing network defense procedures to prevent or rapidly detect these attacks.

APT actors have relied on multiple avenues for initial access. These have included low-effort capabilities such as spearphishing emails and third-party message services directed at both corporate and personal accounts, as well as exploiting vulnerable web-facing devices and remote connection capabilities. Increased telework during the COVID-19 pandemic has expanded workforce reliance on remote connectivity, affording malicious actors more opportunities to exploit those connections and to blend in with increased traffic. Attackers may leverage virtual private networks (VPNs) and other remote work tools to gain initial access or persistence on a victim’s network. When successful, these low-effort, high-reward approaches allow threat actors to steal sensitive information, acquire user credentials, and gain persistent access to victim networks.

Given the importance that think tanks can have in shaping U.S. policy, CISA and FBI urge individuals and organizations in the international affairs and national security sectors to immediately adopt a heightened state of awareness and implement the critical steps listed in the Mitigations section of this Advisory.

Click here for a PDF version of this report.

CISA and FBI recommend think tank organizations apply the following critical practices to strengthen their security posture.


  • Implement a training program to familiarize users with identifying social engineering techniques and phishing emails.


  • Log off remote connections when not in use.
  • Be vigilant against tailored spearphishing attacks targeting corporate and personal accounts (including both email and social media accounts).
  • Use different passwords for corporate and personal accounts.
  • Install antivirus software on personal devices to automatically scan and quarantine suspicious files.
  • Employ strong multi-factor authentication for personal accounts, if available.
  • Exercise caution when:
    • Opening email attachments, even if the attachment is expected and the sender appears to be known. See Using Caution with Email Attachments.
    • Using removable media (e.g., USB thumb drives, external drives, CDs).

IT Staff/Cybersecurity Personnel

  • Segment and segregate networks and functions.
  • Change the default username and password of applications and appliances.
  • Employ strong multi-factor authentication for corporate accounts.
  • Deploy antivirus software on organizational devices to automatically scan and quarantine suspicious files.
  • Apply encryption to data at rest and data in transit.
  • Use email security appliances to scan and remove malicious email attachments or links.
  • Monitor key internal security tools and identify anomalous behavior. Flag any known indicators of compromise or threat actor behaviors for immediate response.
  • Organizations can implement mitigations of varying complexity and restrictiveness to reduce the risk posed by threat actors who use Tor (The Onion Router) to carry out malicious activities. See the CISA-FBI Joint Cybersecurity Advisory on Defending Against Malicious Cyber Activity Originating from Tor for mitigation options and additional information.
  • Prevent exploitation of known software vulnerabilities by routinely applying software patches and upgrades. Foreign cyber threat actors continue to exploit publicly known—and often dated—software vulnerabilities against broad target sets, including public and private sector organizations. If these vulnerabilities are left unpatched, exploitation often requires few resources and provides threat actors with easy access to victim networks. Review CISA and FBI’s Top 10 Routinely Exploited Vulnerabilities and other CISA alerts that identify vulnerabilities exploited by foreign attackers.
  • Implement an antivirus program and a formalized patch management process.
  • Block certain websites and email attachments commonly associated with malware (e.g., .scr, .pif, .cpl, .dll, .exe).
  • Block email attachments that cannot be scanned by antivirus software (e.g., .zip files).
  • Implement Group Policy Object and firewall rules.
  • Implement filters at the email gateway and block suspicious IP addresses at the firewall.
  • Routinely audit domain and local accounts as well as their permission levels to look for situations that could allow an adversary to gain wide access by obtaining credentials of a privileged account.
  • Follow best practices for design and administration of the network to limit privileged account use across administrative tiers.
  • Implement a Domain-Based Message Authentication, Reporting & Conformance (DMARC) validation system.
  • Disable or block unnecessary remote services.
  • Limit access to remote services through centrally managed concentrators.
  • Deny direct remote access to internal systems or resources by using network proxies, gateways, and firewalls.
  • Limit unnecessary lateral communications.
  • Disable file and printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
  • Ensure applications do not store sensitive data or credentials insecurely.
  • Enable a firewall on agency workstations, configured to deny unsolicited connection requests.
  • Disable unnecessary services on agency workstations and servers.
  • Scan for and remove suspicious email attachments; ensure any scanned attachment is its “true file type” (i.e., the extension matches the file header).
  • Monitor users’ web browsing habits; restrict access to suspicious or risky sites. Contact law enforcement or CISA immediately regarding any unauthorized network access identified.
  • Visit the MITRE ATT&CK techniques and tactics pages linked in the ATT&CK Profile section above for additional mitigation and detection strategies for this malicious activity targeting think tanks.


Iranian Advanced Persistent Threat Actor Identified Obtaining Voter Registration Data

This advisory uses the MITRE Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK®) version 7 framework. See the ATT&CK for Enterprise version 7 for all referenced threat actor tactics and techniques.

This joint cybersecurity advisory was coauthored by the Cybersecurity and Infrastructure Security Agency (CISA) and the Federal Bureau of Investigation (FBI). CISA and the FBI are aware of an Iranian advanced persistent threat (APT) actor targeting U.S. state websites—to include election websites. CISA and the FBI assess this actor is responsible for the mass dissemination of voter intimidation emails to U.S. citizens and the dissemination of U.S. election-related disinformation in mid-October 2020.  (Reference FBI FLASH message ME-000138-TT, disseminated October 29, 2020). Further evaluation by CISA and the FBI has identified the targeting of U.S. state election websites was an intentional effort to influence and interfere with the 2020 U.S. presidential election.

Click here for a PDF version of this report.

Analysis by CISA and the FBI indicates this actor scanned state websites, to include state election websites, between September 20 and September 28, 2020, with the Acunetix vulnerability scanner (Active Scanning: Vulnerability Scanning [T1595.002]). Acunetix is a widely used and legitimate web scanner, which has been used by threat actors for nefarious purposes. Organizations that do not regularly use Acunetix should monitor their logs for any activity from the program that originates from IP addresses provided in this advisory and consider it malicious reconnaissance behavior. 

Additionally, CISA and the FBI observed this actor attempting to exploit websites to obtain copies of voter registration data between September 29 and October 17, 2020 (Exploit Public-Facing Application [T1190]). This includes attempted exploitation of known vulnerabilities, directory traversal, Structured Query Language (SQL) injection, web shell uploads, and leveraging unique flaws in websites. 

CISA and the FBI can confirm that the actor successfully obtained voter registration data in at least one state. The access of voter registration data appeared to involve the abuse of website misconfigurations and a scripted process using the cURL tool to iterate through voter records. A review of the records that were copied and obtained reveals the information was used in the propaganda video. 

CISA and FBI analysis of identified activity against state websites, including state election websites, referenced in this product cannot all be fully attributed to this Iranian APT actor. FBI analysis of the Iranian APT actor’s activity has identified targeting of U.S. elections’ infrastructure (Compromise Infrastructure [T1584]) within a similar timeframe, use of IP addresses and IP ranges – including numerous virtual private network (VPN) service exit nodes – which correlate to this Iran APT actor (Gather Victim Host Information [T1592)]), and other investigative information. 


The FBI has information indicating this Iran-based actor attempted to access PDF documents from state voter sites using advanced open-source queries (Search Open Websites and Domains [T1539]). The actor demonstrated interest in PDFs hosted on URLs with the words “vote” or “voter” and “registration.” The FBI identified queries of URLs for election-related sites. 

The FBI also has information indicating the actor researched  the following information in a suspected attempt to further their efforts to survey and exploit state election websites.

  • YOURLS exploit
  • Bypassing ModSecurity Web Application Firewall
  • Detecting Web Application Firewalls
  • SQLmap tool

Acunetix Scanning

CISA’s analysis identified the scanning of multiple entities by the Acunetix Web Vulnerability scanning platform between September 20 and September 28, 2020 (Active Scanning: Vulnerability Scanning [T1595.002]). 

The actor used the scanner to attempt SQL injection into various fields in /registration/registration/details with status codes 404 or 500:

/registration/registration/details?addresscity=-1 or 3*2<(0+5+513-513) -- &addressstreet1=xxxxx&btnbeginregistration=begin voter registration&btnnextelectionworkerinfo=next&btnnextpersonalinfo=next&btnnextresdetails=next&btnnextvoterinformation=next&btnsubmit=submit&chkageverno=on&chkageveryes=on&chkcitizenno=on&chkcitizenyes=on&chkdisabledvoter=on&chkelectionworker=on&chkresprivate=1&chkstatecancel=on&dlnumber=1&dob=xxxx/x/x&[email protected]&firstname=xxxxx&gender=radio&hdnaddresscity=&hdngender=&last4ssn=xxxxx&lastname=xxxxxinjjeuee&[email protected]&[email protected]&[email protected]&[email protected]&mailaddressstate=aa&[email protected]&[email protected]&middlename=xxxxx&overseas=1&partycode=a&phoneno1=xxx-xxx-xxxx&phoneno2=xxx-xxx-xxxx&radio=consent&statecancelcity=xxxxxxx&statecancelcountry=usa&statecancelstate=XXaa&statecancelzip=xxxxx&statecancelzipext=xxxxx&suffixname=esq&[email protected]


The actor used the following requests associated with this scanning activity.

2020-09-26 13:12:56 x.x.x.x GET /x/x v[$acunetix]=1 443 - x.x.x.x Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.21+(KHTML,+like+Gecko)+Chrome/41.0.2228.0+Safari/537.21 - 200 0 0 0

2020-09-26 13:13:19 X.X.x.x GET /x/x voterid[$acunetix]=1 443 - x.x.x.x Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.21+(KHTML,+like+Gecko)+Chrome/41.0.2228.0+Safari/537.21 - 200 0 0 1375

2020-09-26 13:13:18 .X.x.x GET /x/x voterid=;print(md5(acunetix_wvs_security_test)); 443 - X.X.x.x 

User Agents Observed

CISA and FBI have observed the following user agents associated with this scanning activity.

Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.21+(KHTML,+like+Gecko)+Chrome/41.0.2228.0+Safari/537.21 - 500 0 0 0 




Obtaining Voter Registration Data

Following the review of web server access logs, CISA analysts, in coordination with the FBI, found instances of the cURL and FDM User Agents sending GET requests to a web resource associated with voter registration data. The activity occurred between September 29 and October 17, 2020. Suspected scripted activity submitted several hundred thousand queries iterating through voter identification values, and retrieving results with varying levels of success [Gather Victim Identity Information (T1589)]. A sample of the records identified by the FBI reveals they match information in the aforementioned propaganda video.

The actor used the following requests.

2020-10-17 13:07:51 x.x.x.x GET /x/x voterid=XXXX1 443 - x.x.x.x curl/7.55.1 - 200 0 0 1406

2020-10-17 13:07:55 x.x.x.x GET /x/x voterid=XXXX2 443 - x.x.x.x curl/7.55.1 - 200 0 0 1390

2020-10-17 13:07:58 x.x.x.x GET /x/x voterid=XXXX3 443 - x.x.x.x curl/7.55.1 - 200 0 0 1625

2020-10-17 13:08:00 x.x.x.x GET /x/x voterid=XXXX4 443 - x.x.x.x curl/7.55.1 - 200 0 0 1390

Note: incrementing voterid values in cs_uri_query field

User Agents

CISA and FBI have observed the following user agents.



Mozilla/5.0+(Windows+NT+6.1;+WOW64)+AppleWebKit/537.21+(KHTML,+like+Gecko)+Chrome/41.0.2228.0+Safari/537.21 - 500 0 0 0 

See figure 1 below for a timeline of the actor’s malicious activity.

Figure 1: Overview of malicious activity


Acunetix Scanning

Organizations can identify Acunetix scanning activity by using the following keywords while performing log analysis.

  • $acunetix
  • acunetix_wvs_security_test

Indicators of Compromise

For a downloadable copy of IOCs, see AA20-304A.stix.

Disclaimer: Many of the IP addresses included below likely correspond to publicly available VPN services, which can be used by individuals all over the world. Although this creates the potential for false positives, any activity listed should warrant further investigation. The actor likely uses various IP addresses and VPN services.

The following IPs have been associated with this activity.

  • 102.129.239[.]185 (Acunetix Scanning)
  • 143.244.38[.]60 (Acunetix Scanning and cURL requests)
  • 45.139.49[.]228 (Acunetix Scanning)
  • 156.146.54[.]90 (Acunetix Scanning)
  • 109.202.111[.]236 (cURL requests)
  • 185.77.248[.]17 (cURL requests)
  • 217.138.211[.]249 (cURL requests)
  • 217.146.82[.]207 (cURL requests)
  • 37.235.103[.]85 (cURL requests)
  • 37.235.98[.]64 (cURL requests)
  • 70.32.5[.]96 (cURL requests)
  • 70.32.6[.]20 (cURL requests)
  • 70.32.6[.]8 (cURL requests)
  • 70.32.6[.]97 (cURL requests)
  • 70.32.6[.]98 (cURL requests)
  • 77.243.191[.]21 (cURL requests and FDM+3.x (Free Download Manager v3) enumeration/iteration)
  • 92.223.89[.]73 (cURL requests)

CISA and the FBI are aware the following IOCs have been used by this Iran-based actor. These IP addresses facilitated the mass dissemination of voter intimidation email messages on October 20, 2020.

  • 195.181.170[.]244 (Observed September 30 and October 20, 2020)
  • 102.129.239[.]185 (Observed September 30, 2020)
  • 104.206.13[.]27 (Observed September 30, 2020)
  • 154.16.93[.]125 (Observed September 30, 2020)
  • 185.191.207[.]169 (Observed September 30, 2020)
  • 185.191.207[.]52 (Observed September 30, 2020)
  • 194.127.172[.]98 (Observed September 30, 2020)
  • 194.35.233[.]83 (Observed September 30, 2020)
  • 198.147.23[.]147 (Observed September 30, 2020)
  • 198.16.66[.]139(Observed September 30, 2020)
  • 212.102.45[.]3 (Observed September 30, 2020)
  • 212.102.45[.]58 (Observed September 30, 2020)
  • 31.168.98[.]73 (Observed September 30, 2020)
  • 37.120.204[.]156 (Observed September 30, 2020)
  • 5.160.253[.]50 (Observed September 30, 2020)
  • 5.253.204[.]74 (Observed September 30, 2020)
  • 64.44.81[.]68 (Observed September 30, 2020)
  • 84.17.45[.]218 (Observed September 30, 2020)
  • 89.187.182[.]106 (Observed September 30, 2020)
  • 89.187.182[.]111 (Observed September 30, 2020)
  • 89.34.98[.]114 (Observed September 30, 2020)
  • 89.44.201[.]211 (Observed September 30, 2020)


The following list provides recommended self-protection mitigation strategies against cyber techniques used by advanced persistent threat actors: 

  • Validate input as a method of sanitizing untrusted input submitted by web application users. Validating input can significantly reduce the probability of successful exploitation by providing protection against security flaws in web applications. The types of attacks possibly prevented include SQL injection, Cross Site Scripting (XSS), and command injection.
  • Audit your network for systems using Remote Desktop Protocol (RDP) and other internet-facing services. Disable unnecessary services and install available patches for the services in use. Users may need to work with their technology vendors to confirm that patches will not affect system processes.
  • Verify all cloud-based virtual machine instances with a public IP, and avoid using open RDP ports, unless there is a valid need. Place any system with an open RDP port behind a firewall and require users to use a VPN to access it through the firewall.
  • Enable strong password requirements and account lockout policies to defend against brute-force attacks.
  • Apply multi-factor authentication, when possible.
  • Maintain a good information back-up strategy by routinely backing up all critical data and system configuration information on a separate device. Store the backups offline, verify their integrity, and verify the restoration process.
  • Enable logging and ensure logging mechanisms capture RDP logins. Keep logs for a minimum of 90 days and review them regularly to detect intrusion attempts.
  • When creating cloud-based virtual machines, adhere to the cloud provider’s best practices for remote access.
  • Ensure third parties that require RDP access follow internal remote access policies.
  • Minimize network exposure for all control system devices. Where possible, critical devices should not have RDP enabled.
  • Regulate and limit external to internal RDP connections. When external access to internal resources is required, use secure methods, such as a VPNs. However, recognize the security of VPNs matches the security of the connected devices.
  • Use security features provided by social media platforms; use strong passwords, change passwords frequently, and use a different password for each social media account. 
  • See CISA’s Tip on Best Practices for Securing Election Systems for more information. 

General Mitigations

Keep applications and systems updated and patched

Apply all available software updates and patches and automate this process to the greatest extent possible (e.g., by using an update service provided directly from the vendor). Automating updates and patches is critical because of the speed of threat actors to create new exploits following the release of  a patch. These “N-day” exploits can be as damaging as zero-day exploits. Ensure the authenticity and integrity of vendor updates by using signed updates delivered over protected links. Without the rapid and thorough application of patches, threat actors can operate inside a defender’s patch cycle. Additionally, use tools (e.g., the OWASP Dependency-Check Project tool ) to identify the publicly known vulnerabilities in third-party libraries depended upon by the application.

Scan web applications for SQL injection and other common web vulnerabilities

Implement a plan to scan public-facing web servers for common web vulnerabilities (e.g., SQL injection, cross-site scripting) by using a commercial web application vulnerability scanner in combination with a source code scanner. Fixing or patching vulnerabilities after they are identified is especially crucial for networks hosting older web applications. As sites get older, more vulnerabilities are discovered and exposed.

Deploy a web application firewall  

Deploy a web application firewall (WAF) to prevent invalid input attacks and other attacks destined for the web application. WAFs are intrusion/detection/prevention devices that inspect each web request made to and from the web application to determine if the request is malicious. Some WAFs install on the host system and others are dedicated devices that sit in front of the web application. WAFs also weaken the effectiveness of automated web vulnerability scanning tools. 

Deploy techniques to protect against web shells

Patch web application vulnerabilities or fix configuration weaknesses that allow web shell attacks, and follow guidance on detecting and preventing web shell malware. Malicious cyber actors often deploy web shells—software that can enable remote administration—on a victim’s web server. Malicious cyber actors can use web shells to execute arbitrary system commands commonly sent over HTTP or HTTPS. Attackers often create web shells by adding or modifying a file in an existing web application. Web shells provide attackers with persistent access to a compromised network using communications channels disguised to blend in with legitimate traffic. Web shell malware is a long-standing, pervasive threat that continues to evade many security tools. 

Use multi-factor authentication for administrator accounts

Prioritize protection for accounts with elevated privileges, remote access, or used on high-value assets. Use physical token-based authentication systems to supplement knowledge-based factors such as passwords and personal identification numbers (PINs). Organizations should migrate away from single-factor authentication, such as password-based systems, which are subject to poor user choices and more susceptible to credential theft, forgery, and password reuse across multiple systems.

Remediate critical web application security risks

First, identify and remediate critical web application security risks. Next, move on to other less critical vulnerabilities. Follow available guidance on securing web applications.  

How do I respond to unauthorized access to election-related systems?

Implement your security incident response and business continuity plan

It may take time for your organization’s IT professionals to isolate and remove threats to your systems and restore normal operations. In the meantime, take steps to maintain your organization’s essential functions according to your business continuity plan. Organizations should maintain and regularly test backup plans, disaster recovery plans, and business continuity procedures.

Contact CISA or law enforcement immediately 

To report an intrusion and to request incident response resources or technical assistance, contact CISA ([email protected] or 888-282-0870) or the FBI through a local field office or the FBI’s Cyber Division ([email protected] or 855-292-3937).