Hidden Local User Creation

Severity: high
Author: Christian Burkard (Nextron Systems)
Source: upstream

Detects the creation of a local hidden user account which should not happen for event ID 4720.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1136.001` Create Account: Local Account

Event coverage

Provider	Event ID	Title
Security-Auditing	4720	A user account was created.

Stages and Predicates

Stage 1: `selection`

TargetUserName|endswith: '$'

Stage 2: `not 1 of filter_main_homegroup`

TargetUserName: 'HomeGroupUser$'

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.

Field	Kind	Values
`TargetUserName`	ends_with	`$` corpus 18 (sigma 14, elastic 4)
`TargetUserName`	eq	`HomeGroupUser$` corpus 2 (sigma 2)

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.

Local User Creation [sigma] (drops 1 filter this rule applies) (first-stage match only; downstream stages may differ)