Stuxnet Sample - file 63e6b8136058d7a06dfff4034b4ab17a261cdf398e63868a601f77ddd1b32802

Hunt Hypothesis

The detection identifies potential Stuxnet malware activity through a specific file hash, indicating an adversary may be leveraging this sample to target industrial control systems. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate advanced persistent threats that could compromise critical infrastructure.

YARA Rule

rule Stuxnet_Malware_2 
{
   
    meta:
        description = "Stuxnet Sample - file 63e6b8136058d7a06dfff4034b4ab17a261cdf398e63868a601f77ddd1b32802"
        author = "Florian Roth"
        reference = "Internal Research"
        date = "2016-07-09"
        hash1 = "63e6b8136058d7a06dfff4034b4ab17a261cdf398e63868a601f77ddd1b32802"
   
    strings:
        $s1 = "\\SystemRoot\\System32\\hal.dll" fullword wide
        $s2 = "http://www.jmicron.co.tw0" fullword ascii
   
    condition:
        uint16(0) == 0x5a4d and filesize < 70KB and all of them
}

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 2 string patterns in its detection logic.

References

• Internal Research
• Source Rule

False Positive Guidance

• Scenario: Legitimate Windows Update or Patching Process
  Description: A system may download and execute a file with a hash matching the Stuxnet sample during a legitimate Windows update or patching process.
  Filter/Exclusion: Check the process.parent field to ensure the parent process is a known update service (e.g., wuauserv, svchost.exe), or filter by process.name to exclude known update-related processes.

• Scenario: Scheduled Job Running Antivirus Scan
  Description: An antivirus tool may scan a file that matches the Stuxnet hash as part of a scheduled scan, triggering the rule.
  Filter/Exclusion: Include process.name like mpsvr32.exe, avgnt.exe, or mcafee.exe to identify legitimate antivirus processes. Alternatively, filter by file.hash to exclude known safe files.

• Scenario: Admin Task Involving File Integrity Monitoring (FIM)
  Description: An admin may use a tool like Microsoft Advanced Threat Analytics (ATA) or Microsoft Defender for Endpoint to monitor and analyze files, which could include a file with the same hash as the Stuxnet sample.
  Filter/Exclusion: Filter by process.name such as microsoft-edge.exe, msedge.exe, or microsoft-ata.exe, or check the user field to identify admin tasks.

• Scenario: File Integrity Check Using Tripwire or Similar Tools
  Description: A file integrity monitoring tool like Tripwire or OSSEC may compare files against a known good hash, which could match the Stuxnet sample hash.
  Filter/Exclusion: Filter by process.name such as tripwire, ossec, or filemon.exe, or check the process.parent to identify