PolyBoxDAnskya

Hunt Hypothesis

This YARA rule targets the PolyBoxDAnskya signature, which indicates the presence of a specific low-severity malware variant or suspicious code pattern often associated with initial access or persistence mechanisms. Proactively hunting for this signature allows the SOC team to identify latent threats in Azure Sentinel that may not yet trigger high-fidelity alerts, enabling early containment of potentially compromised workloads or endpoints.

YARA Rule

rule PolyBoxDAnskya
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 33 C9 51 51 51 51 51 53 33 C0 55 68 84 2C 40 00 64 FF 30 64 89 20 C6 45 FF 00 B8 B8 46 40 00 BA 24 00 00 00 E8 8C F3 FF FF 6A 24 BA B8 46 40 00 8B 0D B0 46 40 00 A1 94 46 40 00 E8 71 FB FF FF 84 C0 0F 84 6E 01 00 00 8B 1D D0 46 40 00 8B C3 83 C0 24 03 05 D8 46 40 00 3B 05 B4 46 40 00 0F 85 51 01 00 00 8D 45 F4 BA B8 46 40 00 B9 10 00 00 00 E8 A2 EC FF FF 8B 45 F4 BA 9C 2C 40 00 E8 F1 ED FF FF }

condition:
		$a0
}

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 legacy Java-based Enterprise Resource Planning (ERP) module (e.g., SAP NetWeaver or Oracle EBS) executes a custom .jar file containing embedded native libraries or obfuscated bytecode during nightly batch processing jobs. The YARA rule PolyBoxDAnskya may match the specific byte sequence or string pattern within the JAR’s manifest or class files, triggering an alert despite the process running under a known service account.

  • Filter/Exclusion: Exclude alerts where the file path matches C:\Program Files\SAP\* or C:\Oracle\Middleware\* AND the parent process is java.exe or jre.exe AND the user context is a dedicated service account (e.g., svc_erp_batch).

• Scenario: An IT administrator deploys a new version of a proprietary endpoint management agent (e.g., Ivanti, ManageEngine, or a custom in-house tool) via Group Policy or a configuration management tool (e.g., SCCM/MECM). The installer or updater writes a temporary .dll or .exe to %TEMP% or %ProgramData% that contains a specific version string or GUID pattern matched by the YARA rule.

  • Filter/Exclusion: Exclude alerts where the file path contains \ProgramData\ or \Temp\ AND the parent process is ccmsetup.exe, msiexec.exe, or gpupdate.exe AND the file creation time is within 5 minutes of the policy application timestamp.

• Scenario: A developer or data scientist runs a Python script using pip install or conda to update scientific computing libraries (e.g., NumPy, Pandas, or SciPy) on a jump host or build server. The compiled C extensions (.pyd files on Windows) or bundled binaries may contain specific linker strings or version