Sigma rule: Explorer NOUACCHECK Flag

Rule

Title

Explorer NOUACCHECK Flag

Status

test

Level

high

Author

Florian Roth (Nextron Systems)

Date

2022-02-23

Modified

2022-04-21

File

rules/windows/process_creation/proc_creation_win_explorer_nouaccheck.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious starts of explorer.exe that use the /NOUACCHECK flag that allows to run all sub processes of that newly started explorer.exe without any UAC checks

Log source

product

windows

category

process_creation

Detection

selection:
    Image|endswith: '\explorer.exe'
    CommandLine|contains: '/NOUACCHECK'
filter_dc_logon:
    - ParentCommandLine: 'C:\Windows\system32\svchost.exe -k netsvcs -p -s Schedule'
    - ParentImage: 'C:\Windows\System32\svchost.exe' # coarse filter needed for ID 4688 Events
condition: selection and not 1 of filter_*

False positives (as the rule lists them)

• Domain Controller User Logon
• Unknown how many legitimate software products use that method

Tags

• attack.privilege-escalation
• attack.t1548.002

MITRE ATT&CK ids this rule names

• T1548.002

References

• https://twitter.com/ORCA6665/status/1496478087244095491

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_explorer_nouaccheck.yml