Detection rules › Sigma
User account created by a computer account
Detects scenarios where an attacker would abuse some privileges while realying host credentials to escalate privileges.
Known false positives
- Exchange servers
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | |
| Stealth |
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Security-Auditing | Event ID 4720: A user account was created. |
Rule body
title: User account created by a computer account
description: Detects scenarios where an attacker would abuse some privileges while realying host credentials to escalate privileges.
references:
- https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4741
tags:
- attack.persistence
- attack.t1136 # user creation
- attack.defense_evesion
- attack.t1036 # masquerading
author: mdecrevoisier
status: experimental
logsource:
product: windows
service: security
detection:
selection:
EventID: 4720
SubjectUserName|endswith: '$' # Computer account
SubjectUserSid|startswith: 'S-1-5-21-' # SYSTEM account 'S-1-5-18' would trigger a false positive
filter:
TargetUserName|endswith: '$' # covered in another rule: User account creation disguised in a computer account
condition: selection
falsepositives:
- Exchange servers
level: high
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
EventID: 4720
SubjectUserName|endswith: '$'
SubjectUserSid|startswith: 'S-1-5-21-'
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
SubjectUserName | ends_with |
| field:"SubjectUserName" kind:ends_with value:"$" |
SubjectUserSid | starts_with |
| field:"SubjectUserSid" kind:starts_with value:"S-1-5-21-" |