Sigma rule: Bypass UAC Using SilentCleanup Task

Rule

Title

Bypass UAC Using SilentCleanup Task

Status

test

Level

high

Author

frack113, Nextron Systems

Date

2022-01-06

Modified

2024-01-30

File

rules/windows/registry/registry_set/registry_set_bypass_uac_using_silentcleanup_task.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the setting of the environement variable "windir" to a non default value.
Attackers often abuse this variable in order to trigger a UAC bypass via the "SilentCleanup" task.
The SilentCleanup task located in %windir%\system32\cleanmgr.exe is an auto-elevated task that can be abused to elevate any file with administrator privileges without prompting UAC.

Log source

product

windows

category

registry_set

Detection

selection:
    TargetObject|endswith: '\Environment\windir'
filter_main_default:
    Details: '%SystemRoot%'
condition: selection and not 1 of filter_main_*

False positives (as the rule lists them)

• Unknown

Tags

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

MITRE ATT&CK ids this rule names

• T1548.002

References

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1548.002/T1548.002.md#atomic-test-9---bypass-uac-using-silentcleanup-task
• https://www.reddit.com/r/hacking/comments/ajtrws/bypassing_highest_uac_level_windows_810/
• https://www.fortinet.com/blog/threat-research/enter-the-darkgate-new-cryptocurrency-mining-and-ransomware-campaign

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/registry/registry_set/registry_set_bypass_uac_using_silentcleanup_task.yml