Windows: Detect Computer Account Rename to Non-Standard Name Missing Trailing '$'

Alerts on Windows 4781 computer account renames where the new name lacks the '$' suffix.

FreeReviewedSigma · High · v5

Product: windows
Service: security
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-12-22
Updated: 2026-07-31

ATT&CK techniques

Persistence → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1098Account Manipulation
Priv Esc
- T1098Account Manipulation
Defense Evasion
- T1036Masquerading
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Security event 4781 where an existing computer account is renamed such that the new account name does not contain a '$' character. Attackers may abuse computer account name spoofing to support stealthy persistence and privilege escalation behaviors associated with SAM account naming misuse. It relies on Windows Security auditing for account rename events and the old/new target account name fields captured in the event telemetry.

Reporting behind it

Related detections9 linkedT1036 — drag to rearrange

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Windows: Detect Computer Account Rename to Non-Standard Name Missing Trailing '$'

Pivot detection · T1036 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-security-detect-computer-account-renamed-to-missing-suffix-45eb2ae2

title: "Windows: Detect Computer Account Rename to Non-Standard Name Missing Trailing '$'"
id: 3ea34a32-4f6a-47bc-93a8-ba5266ec2f3c
status: test
description: This rule flags Security event 4781 where an existing computer account is renamed such that the new account name does not contain a '$' character. Attackers may abuse computer account name spoofing to support stealthy persistence and privilege escalation behaviors associated with SAM account naming misuse. It relies on Windows Security auditing for account rename events and the old/new target account name fields captured in the event telemetry.
references:
  - https://medium.com/@mvelazco/hunting-for-samaccountname-spoofing-cve-2021-42287-and-domain-controller-impersonation-f704513c8a45
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2021/Exploits/CVE-2021-42287/win_security_samaccountname_spoofing_cve_2021_42287.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2021-12-22
modified: 2022-12-25
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.stealth
  - attack.t1036
  - attack.t1098
  - cve.2021-42287
  - detection.emerging-threats
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 4781
    OldTargetUserName|contains: $
  filter:
    NewTargetUserName|contains: $
  condition: selection and not filter
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 45eb2ae2-9aa2-4c3a-99a5-6e5077655466
    type: derived

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