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Citrus Ransomware Sn00py VLESS Tunnels: Detection & IOCs

Citrus pushes Sn00py ransomware through malicious Group Policy Objects after VLESS tunneling. 9 detection rules, 22 IOCs and a free Splunk SPL rule.

Read the full threat intel for Citrus Ransomware Sn00py VLESS Tunnels: Detection & IOCs →

Chapters

  1. 0:00The hookCitrus attacks only Russian companies.
  2. 0:04The storyIt starts with stolen credentials.
  3. 0:11Attack pathEntry comes via VPN or RDP.
  4. 0:25AttributionAttributed to Citrus.
  5. 0:29Indicators of compromise17 indicators to hunt: 2 IPs, 6 MD5 hashes and 4 file names, and more.
  6. 0:38MITRE ATT&CK techniques18 ATT&CK techniques, from initial access to impact.
  7. 0:42Remediation5 steps now: Restrict and monitor contractor access, including VPN and RDP.
  8. 0:50Detection rules9 detection rules, in SPL, KQL and Sigma.
Transcript

0:00Citrus attacks only Russian companies.

0:05It starts with stolen credentials.

0:07Then ransomware encrypts user files.

0:11Entry comes via VPN or RDP.

0:14Traffic hides in a Yandex-like tunnel.

0:16Next, they reach domain controllers.

0:19Defender is switched off.

0:20Files end in .citrus.

0:25Attributed to Citrus. Confidence: medium.

0:3017 indicators to hunt: 2 IPs, 6 MD5 hashes and 4 file names, and more.

0:3818 ATT&CK techniques, from initial access to impact.

0:435 steps now: Restrict and monitor contractor access, including VPN and RDP.

0:519 detection rules, in SPL, KQL and Sigma.

0:56Threadlinqs. The unified security engineering platform.