Stuxnet Sample - file malware.exe

Hunt Hypothesis

The detection identifies a Stuxnet malware sample, malware.exe, which is associated with sophisticated industrial espionage activities. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential targeted attacks on critical infrastructure.

YARA Rule

rule StuxNet_Malware_1 
{

    meta:
        description = "Stuxnet Sample - file malware.exe"
        author = "Florian Roth"
        reference = "Internal Research"
        date = "2016-07-09"
        hash1 = "9c891edb5da763398969b6aaa86a5d46971bd28a455b20c2067cb512c9f9a0f8"
    
    strings:
         // 0x10001778 8b 45 08  mov     eax, dword ptr [ebp + 8]
         // 0x1000177b 35 dd 79 19 ae    xor     eax, 0xae1979dd
         // 0x10001780 33 c9     xor     ecx, ecx
         // 0x10001782 8b 55 08  mov     edx, dword ptr [ebp + 8]
         // 0x10001785 89 02     mov     dword ptr [edx], eax
         // 0x10001787 89 ?? ??  mov     dword ptr [edx + 4], ecx
         $op1 = { 8b 45 08 35 dd 79 19 ae 33 c9 8b 55 08 89 02 89 }
         // 0x10002045 74 36     je      0x1000207d
         // 0x10002047 8b 7f 08  mov     edi, dword ptr [edi + 8]
         // 0x1000204a 83 ff 00  cmp     edi, 0
         // 0x1000204d 74 2e     je      0x1000207d
         // 0x1000204f 0f b7 1f  movzx   ebx, word ptr [edi]
         // 0x10002052 8b 7f 04  mov     edi, dword ptr [edi + 4]
         $op2 = { 74 36 8b 7f 08 83 ff 00 74 2e 0f b7 1f 8b 7f 04 }
         // 0x100020cf 74 70     je      0x10002141
         // 0x100020d1 81 78 05 8d 54 24 04      cmp     dword ptr [eax + 5], 0x424548d
         // 0x100020d8 75 1b     jne     0x100020f5
         // 0x100020da 81 78 08 04 cd ?? ??      cmp     dword ptr [eax + 8], 0xc22ecd04
         $op3 = { 74 70 81 78 05 8d 54 24 04 75 1b 81 78 08 04 cd }
  
    condition:
        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 3 string patterns in its detection logic.

References

• Internal Research
• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate scheduled task runs malware.exe as part of a routine system maintenance or patching process.
  Filter/Exclusion: Check the command line arguments and process tree. Exclude processes where malware.exe is invoked by schtasks.exe or Task Scheduler with known maintenance task names (e.g., PatchManager.exe).

• Scenario: Antivirus Quarantine Process
  Description: An endpoint security tool (e.g., Bitdefender, Kaspersky) quarantines a file named malware.exe during a scan, temporarily renaming or moving it.
  Filter/Exclusion: Filter out processes initiated by antivirus tools (e.g., bdagent.exe, kavsvc.exe) or check for file hashes in known quarantine directories.

• Scenario: Software Deployment via SCCM
  Description: A deployment package (e.g., via Microsoft System Center Configuration Manager) includes a file named malware.exe as part of a legitimate software update.
  Filter/Exclusion: Check the process parent for smsts.exe or ccmexec.exe and verify the file path against known SCCM deployment directories (e.g., C:\Windows\Temp\SCCM).

• Scenario: Log File Parsing or Conversion
  Description: A log processing tool (e.g., Splunk, ELK Stack) generates a temporary file named malware.exe during log parsing or conversion tasks.
  Filter/Exclusion: Exclude processes initiated by log processing tools (e.g., splunkd.exe, logstash.exe) and check for file extensions or content that indicate log files rather than executable files.

• Scenario: User-Initiated File Rename or Copy
  Description: A user renames or copies a file named `