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
drilldown_searches:
    - name: View the detection results for - "$dest$" and "$OldTargetUserName$"
      search: '%original_detection_search% | search  dest = "$dest$" OldTargetUserName = "$OldTargetUserName$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$OldTargetUserName$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$OldTargetUserName$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
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
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1078.002/suspicious_computer_account_name_change/windows-xml.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit