Detection rules › Sigma

Hiding User Account Via SpecialAccounts Registry Key - CommandLine

Severity
medium
Author
@Kostastsale, TheDFIRReport
Source
upstream

Detects changes to the registry key "HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\Userlist" where the value is set to "0" in order to hide user account from being listed on the logon screen.

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1564.002 Hide Artifacts: Hidden Users

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation
Security-Auditing4688A new process has been created.

Stages and Predicates

Stage 1: selection

CommandLine|contains: '/d 0'
CommandLine|contains: '/v'
CommandLine|contains: '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList'
CommandLine|contains: add
Image|endswith: '\reg.exe'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • /d 0 corpus 2 (sigma 2)
  • /v corpus 4 (sigma 4)
  • \SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList
  • add corpus 16 (sigma 16)
Imageends_with
  • \reg.exe corpus 46 (sigma 46)