Rewterz Threat Alert – CactusPete APT Group’s Updated Bisonal Backdoor

Severity

High

Analysis Summary

Researchers have published an analysis of a new CactusPete APT campaign against Eastern European financial and military organizations and the associated Bisonal backdoor. While the official infection vector has not been observed, CactusPete typically uses spear-phishing emails with malicious attachments to deliver their payload. Once on the system, the Bisonal backdoor establishes RC4-encrypted communication with its C2 server over HTTP. The initial check-in provides victim details, such as hostname, IP address, Windows version, proxy usage, and more. After the connection is completed, the backdoor periodically queries the C2 server for any commands. Commands include those to execute a remote shell, start programs, terminate processes, upload or download files, and retrieve file lists. These commands are issued by the group to perform lateral movement and gain deeper access. They have also been known to use Mimikatz and keyloggers for credential harvesting and privilege escalation.

Impact

• Financial loss
• Credential harvesting
• Privilege escalation

Indicators of Compromise

MD5

• A3F6818CE791A836F54708F5FB9935F3
• 3E431E5CF4DA9CAE83C467BC1AE818A0
• 11B8016045A861BE0518C9C398A79573

Remediation

• Block all threat indicators at your respective controls.
• Search for IOCs in your environment.