Hiding User Account Via SpecialAccounts Registry Key

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems), frack113
Source: upstream

Detects modifications 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

Tactic	Techniques
Defense Evasion	`T1564.002` Hide Artifacts: Hidden Users

Event coverage

Provider	Event ID	Title
Sysmon	13	RegistryEvent (Value Set)

Stages and Predicates

Stage 1: `selection`

Details: 'DWORD (0x00000000)'
TargetObject|contains: '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList'

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.