PseudoSigner02MEW11SE10Anorganix

Hunt Hypothesis

This YARA rule identifies potentially malicious or obfuscated code artifacts associated with the “Anorganix” signature, which may indicate the presence of a low-severity threat or a specific malware family attempting to establish a foothold. Proactively hunting for these indicators in Azure Sentinel allows the SOC team to detect subtle or emerging threats that might be missed by standard signature-based detections, ensuring early identification of anomalous file activity before it escalates.

YARA Rule

rule PseudoSigner02MEW11SE10Anorganix
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E9 09 00 00 00 00 00 00 02 00 00 00 0C 90 }

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

• Scenario: A developer or DevOps engineer runs a custom Python script or PowerShell wrapper to generate a temporary self-signed certificate for local API testing or internal service communication. The script uses a library like pyOpenSSL or System.Security.Cryptography to create a certificate with a subject name containing “Anorganix” (or similar pseudo-random/placeholder text) and a specific key size, triggering the YARA pattern match for pseudo-signing artifacts.

  • Filter/Exclusion: Exclude processes where the parent process is python.exe, python3.exe, or pwsh.exe and the command line contains arguments related to certificate generation (e.g., genkey, req, -NewSelfSignedCertificate). Additionally, exclude file paths under common development directories like C:\Users\<user>\dev\ or C:\Projects\.

• Scenario: An automated backup or archival job (e.g., Veeam, Commvault, or a custom PowerShell script) creates a temporary staging file or metadata blob that includes a hash or identifier string matching the “Anorganix” pattern as part of a unique job ID or checksum prefix. The YARA rule may be matching on a specific byte sequence or string within the file header that coincides with the rule’s condition.

  • Filter/Exclusion: Exclude files located in known backup staging directories (e.g., C:\ProgramData\Veeam\, C:\Commvault\) or files with extensions like .vbk, .dat, or .tmp created by backup service accounts. Correlate with the service account name (e.g., svc-backup) in the process log.

• Scenario: A third-party application installer or updater (e.g., Adobe Creative Cloud, JetBrains Toolbox, or a custom internal tool) uses a pseudo-random or placeholder signing string during the installation or update process to verify integrity before