Suspicious Computer Account Name Change

name: Suspicious Computer Account Name Change
id: 35a61ed8-61c4-11ec-bc1e-acde48001122
version: 14
creation_date: '2021-12-20'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects a suspicious computer account name change in Active Directory. It leverages Event ID 4781, which logs account name changes, to identify instances where a computer account name is changed to one that does not end with a `$`. This behavior is significant as it may indicate an attempt to exploit CVE-2021-42278 and CVE-2021-42287, which can lead to domain controller impersonation and privilege escalation. If confirmed malicious, this activity could allow an attacker to gain elevated privileges and potentially control the domain.
data_source:
    - Windows Event Log Security 4781
search: |-
    `wineventlog_security` EventCode=4781 OldTargetUserName="*$" NewTargetUserName!="*$"
      | table _time, Computer, Caller_User_Name, OldTargetUserName, NewTargetUserName
      | rename Computer as dest
      | `suspicious_computer_account_name_change_filter`
how_to_implement: To successfully implement this search, you need to be ingesting Windows event logs from your hosts. In addition, the Splunk Windows TA is needed.
known_false_positives: Renaming a computer account name to a name that not end with '$' is highly unsual and may not have any legitimate scenarios.
references:
    - https://exploit.ph/cve-2021-42287-cve-2021-42278-weaponisation.html
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42278
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42287
finding:
    title: A computer account $OldTargetUserName$ was renamed with a suspicious computer name on $dest$
    entity:
        field: OldTargetUserName
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: A computer account $OldTargetUserName$ was renamed with a suspicious computer name on $dest$
analytic_story:
    - Active Directory Privilege Escalation
    - Compromised Windows Host
    - sAMAccountName Spoofing and Domain Controller Impersonation
    - Scattered Lapsus$ Hunters
asset_type: Endpoint
cve:
    - CVE-2021-42287
    - CVE-2021-42278
mitre_attack_id:
    - T1078.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint