Sigma rule: Bypass UAC via CMSTP

Rule

Title

Bypass UAC via CMSTP

Status

test

Level

high

Author

E.M. Anhaus (originally from Atomic Blue Detections, Endgame), oscd.community

Date

2019-10-24

Modified

2022-08-30

File

rules/windows/process_creation/proc_creation_win_uac_bypass_cmstp.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detect commandline usage of Microsoft Connection Manager Profile Installer (cmstp.exe) to install specially formatted local .INF files

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith: '\cmstp.exe'
    - OriginalFileName: 'CMSTP.EXE'
selection_cli:
    CommandLine|contains:
        - '/s'
        - '-s'
        - '/au'
        - '-au'
        - '/ni'
        - '-ni'
condition: all of selection*

False positives (as the rule lists them)

• Legitimate use of cmstp.exe utility by legitimate user

Tags

• attack.privilege-escalation
• attack.stealth
• attack.t1548.002
• attack.t1218.003

MITRE ATT&CK ids this rule names

• T1218.003
• T1548.002

References

• https://eqllib.readthedocs.io/en/latest/analytics/e584f1a1-c303-4885-8a66-21360c90995b.html
• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1218.003/T1218.003.md
• https://lolbas-project.github.io/lolbas/Binaries/Cmstp/

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_uac_bypass_cmstp.yml