Sigma rule: Windows MSIX Package Support Framework AI_STUBS Execution

Rule

Title

Windows MSIX Package Support Framework AI_STUBS Execution

Status

experimental

Level

low

Author

Michael Haag, Swachchhanda Shrawan Poudel (Nextron Systems)

Date

2025-11-03

File

rules/windows/process_creation/proc_creation_win_msix_ai_stub_execution.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects execution of Advanced Installer MSIX Package Support Framework (PSF) components, specifically AI_STUBS executables with original filename 'popupwrapper.exe'.
This activity may indicate malicious MSIX packages build with Advanced Installer leveraging the Package Support Framework to bypass application control restrictions.

Log source

product

windows

category

process_creation

Detection

selection:
    Image|endswith:
        - '\AI_STUBS\AiStubX64Elevated.exe'
        - '\AI_STUBS\AiStubX86Elevated.exe'
        - '\AI_STUBS\AiStubX64.exe'
        - '\AI_STUBS\AiStubX86.exe'
    OriginalFileName: 'popupwrapper.exe'
condition: selection

False positives (as the rule lists them)

• Legitimate applications packaged with Advanced Installer using Package Support Framework

Tags

• attack.execution
• attack.stealth
• attack.defense-impairment
• attack.t1218
• attack.t1553.005
• attack.t1204.002

MITRE ATT&CK ids this rule names

• T1204.002
• T1218
• T1553.005

References

• https://redcanary.com/blog/threat-intelligence/msix-installers/
• https://redcanary.com/threat-detection-report/techniques/installer-packages/
• https://learn.microsoft.com/en-us/windows/msix/package/package-support-framework
• https://www.splunk.com/en_us/blog/security/msix-weaponization-threat-detection-splunk.html

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_msix_ai_stub_execution.yml