Bypass UAC via CMSTP

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

Sigma rule (View on GitHub)

 1title: Bypass UAC via CMSTP
 2id: e66779cc-383e-4224-a3a4-267eeb585c40
 3status: test
 4description: Detect commandline usage of Microsoft Connection Manager Profile Installer (cmstp.exe) to install specially formatted local .INF files
 5references:
 6    - https://eqllib.readthedocs.io/en/latest/analytics/e584f1a1-c303-4885-8a66-21360c90995b.html
 7    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1218.003/T1218.003.md
 8    - https://lolbas-project.github.io/lolbas/Binaries/Cmstp/
 9author: E.M. Anhaus (originally from Atomic Blue Detections, Endgame), oscd.community
10date: 2019/10/24
11modified: 2022/08/30
12tags:
13    - attack.privilege_escalation
14    - attack.defense_evasion
15    - attack.t1548.002
16    - attack.t1218.003
17logsource:
18    category: process_creation
19    product: windows
20detection:
21    selection_img:
22        - Image|endswith: '\cmstp.exe'
23        - OriginalFileName: 'CMSTP.EXE'
24    selection_cli:
25        CommandLine|contains:
26            - '/s'
27            - '-s'
28            - '/au'
29            - '-au'
30            - '/ni'
31            - '-ni'
32    condition: all of selection*
33fields:
34    - ComputerName
35    - User
36    - CommandLine
37falsepositives:
38    - Legitimate use of cmstp.exe utility by legitimate user
39level: high

References

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