CISA and FBI Issue Warning About Rhysida Ransomware Double Extortion Attacks

The threat actors behind the Rhysida ransomware engage in opportunistic attacks targeting organizations spanning various industry sectors.

The advisory comes courtesy of the U.S. Cybersecurity and Infrastructure Security Agency (CISA), the Federal Bureau of Investigation (FBI), and the Multi-State Information Sharing and Analysis Center (MS-ISAC).

“Observed as a ransomware-as-a-service (RaaS) model, Rhysida actors have compromised organizations in education, manufacturing, information technology, and government sectors and any ransom paid is split between the group and affiliates,” the agencies said.

“Rhysida actors leverage external-facing remote services, such as virtual private networks (VPNs), Zerologon vulnerability (CVE-2020-1472), and phishing campaigns to gain initial access and persistence within a network.”

First detected in May 2023, Rhysida makes use of the time-tested tactic of double extortion, demanding a ransom payment to decrypt victim data and threatening to publish the exfiltrated data unless the ransom is paid.

It’s also said to share overlaps with another ransomware crew known as Vice Society (aka Storm-0832 or Vanilla Tempest), owing to similar targeting patterns and the use of NTDSUtil as well as PortStarter, which has been exclusively employed by the latter.

According to statistics compiled by Malwarebytes, Rhysida has claimed five victims for the month of October 2023, putting it far behind LockBit (64), NoEscape (40), PLAY (36), ALPHV/BlackCat (29), and 8BASE (21).

The agencies described the group as engaging in opportunistic attacks to breach targets and taking advantage of living-off-the-land (LotL) techniques to facilitate lateral movement and establish VPN access.

In doing so, the idea is to evade detection by blending in with legitimate Windows systems and network activities.

Vice Society’s pivot to Rhysida has been bolstered in the wake of new research published by Sophos earlier last week, which said it observed the same threat actor using Vice Society up until June 2023, when it switched to deploying Rhysida.

The cybersecurity company is tracking the cluster under the name TAC5279.

“Notably, according to the ransomware group’s data leak site,…