Windows Security: New or Renamed User Account Name Containing '$'

ATT&CK techniques

Defense Evasion

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

What it detects

This rule flags Windows Security events where a user account is created or renamed and the account name contains the '$' character. Attackers may use this to obscure naming and potentially bypass simpler detections that do not account for special characters in user names. The detection relies on Windows account management telemetry from EventID 4720 (user created) and EventID 4781 (user renamed), inspecting SamAccountName and NewTargetUserName fields while excluding the specific HomeGroupUser$ pattern.

Reporting behind it

Related detections9 linkedT1036 — drag to rearrange

Suspicious EAGERBEE Configuration File Created in Public User Directory via File Event

Malicious DLL Execution With Non Standard Extension via rundll32

Suspicious Rclone Exfiltration Masquerading as wininit.exe

Suspicious Executable Running from Public Pictures Directory

Suspicious Python Execution via Renamed Synaptics Binary

Agent Tesla Persistence via Realtek Named Scheduled Task Batch

Suspicious Interlock Fake Updater Executable Execution

Malicious User Account Created by a Computer Account (via security)

Suspicious Execution of agent.exe From WinSyncDefender AppData Directory (via process_creation)

Windows Security: New or Renamed User Account Name Containing '$'

Pivot detection · T1036 · 9 related

Changelog

v2

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-new-or-renamed-user-account-name-contains-cfeed607

title: "Windows Security: New or Renamed User Account Name Containing '$'"
id: 9c236287-52b4-44da-b98a-921618858bfe
status: test
description: This rule flags Windows Security events where a user account is created or renamed and the account name contains the '$' character. Attackers may use this to obscure naming and potentially bypass simpler detections that do not account for special characters in user names. The detection relies on Windows account management telemetry from EventID 4720 (user created) and EventID 4781 (user renamed), inspecting SamAccountName and NewTargetUserName fields while excluding the specific HomeGroupUser$ pattern.
references:
  - https://twitter.com/SBousseaden/status/1387743867663958021
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_new_or_renamed_user_account_with_dollar_sign.yml
author: Ilyas Ochkov, oscd.community, Huntrule Team
date: 2019-10-25
modified: 2024-01-16
tags:
  - attack.stealth
  - attack.t1036
logsource:
  product: windows
  service: security
detection:
  selection_create:
    EventID: 4720
    SamAccountName|contains: $
  selection_rename:
    EventID: 4781
    NewTargetUserName|contains: $
  filter_main_homegroup:
    EventID: 4720
    TargetUserName: HomeGroupUser$
  condition: 1 of selection_* and not 1 of filter_main_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: cfeed607-6aa4-4bbd-9627-b637deb723c8
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL