CDSSS10beta1CyberDoom

Hunt Hypothesis

This rule detects the presence of the CyberDoom malware variant, a low-severity threat often associated with initial access or reconnaissance activities. Proactively hunting for this signature allows the SOC team to identify compromised endpoints early in the kill chain, enabling rapid containment before the adversary can establish persistence or escalate privileges within the Azure environment.

YARA Rule

rule CDSSS10beta1CyberDoom
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 5D 81 ED CA 47 40 00 FF 74 24 20 E8 D3 03 00 00 0B C0 0F 84 13 03 00 00 89 85 B8 4E 40 00 66 8C D8 A8 04 74 0C C7 85 8C 4E 40 00 01 00 00 00 EB 12 64 A1 30 00 00 00 0F B6 40 02 0A C0 0F 85 E8 02 00 00 8D 85 F6 4C 40 00 50 FF B5 B8 4E 40 00 E8 FC 03 00 00 0B C0 0F 84 CE 02 00 00 E8 1E 03 00 00 89 85 90 4E 40 00 8D 85 03 4D 40 00 50 FF B5 B8 4E 40 00 E8 D7 03 00 00 0B C0 0F 84 A9 02 00 00 E8 F9 02 00 00 89 85 94 4E 40 00 8D 85 12 4D 40 00 50 }

condition:
		$a0 at pe.entry_point
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Legacy Application Maintenance: The rule may trigger on the CyberDoom executable (or its associated DLLs) when legacy enterprise applications (e.g., old versions of Adobe Creative Suite, specific CAD tools, or internal proprietary software) perform routine background updates or license validation.
  • Filter/Exclusion: Allowlist the specific file path (e.g., C:\Program Files\LegacyApp\bin\CyberDoom.exe) and restrict the trigger to only when the process is initiated by a known service account or scheduled task ID.
• Antivirus/EDR Signature Update: During full signature database updates, security tools like CrowdStrike Falcon, SentinelOne, or Microsoft Defender for Endpoint may temporarily load or scan YARA rule files containing the string CDSSS10beta1CyberDoom if it is part of a custom or third-party rule pack.
  • Filter/Exclusion: Exclude processes where the parent process is a known security agent (e.g., FalconSensor.exe, SentinelOneAgent.exe, MsMpEng.exe) and the file extension is .yar or .yara.
• Development and Testing Environments: Developers or QA engineers running local YARA scanning tools (such as yara CLI, yara-python, or yara-dotnet) against a corpus of test files or CI/CD pipeline artifacts that include the rule definition.
  • Filter/Exclusion: Exclude processes running from development directories (e.g., C:\dev\, C:\work\, C:\temp\) or where the parent process is a development tool (e.g., code.exe, idea64.exe, python.exe, node.exe).
• Scheduled Backup or Archiving Jobs: Enterprise backup solutions (e.g., Veeam, Commvault, or Windows