Detect Computer Changed with Anonymous Account

Name:Detect Computer Changed with Anonymous Account
id:1400624a-d42d-484d-8843-e6753e6e3645
version:10
date:2026-03-18
author:Rod Soto, Jose Hernandez, Splunk
status:production
type:Hunting
Description:The following analytic detects changes to computer accounts using an anonymous logon. It leverages Windows Security Event Codes 4742 (Computer Change) with a SubjectUserName of a value "ANONYMOUS LOGON". This activity can be significant because anonymous logons should not typically be modifying computer accounts, indicating potential unauthorized access or misconfiguration. If confirmed malicious, this could allow an attacker to alter computer accounts, potentially leading to privilege escalation or persistent access within the network.
Data_source:

• -Windows Event Log Security 4742

search:`wineventlog_security`
EventCode=4742
SubjectUserName="ANONYMOUS LOGON"
PasswordLastSet="*"
| stats count min(_time) as firstTime max(_time) as lastTime
BY action app dest ProcessID PasswordLastSet
signature signature_id src_user status
SubjectDomainName user user_group vendor_product
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `detect_computer_changed_with_anonymous_account_filter`

how_to_implement:This search requires "Audit Computer Account Management" sub-category in the audit policy to be enabled on the system in order to generate Event ID 4742, as well as "Audit Logon" to generate Event ID 4624. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Windows Event Logs. Replace the macro definition with configurations for your Splunk environment. The search also uses a post-filter macro designed to filter out known false positives.
known_false_positives:Some legitimate, legacy devices may utilize this functionality and generate false positives. Apply additional tuning as needed.
References:
  -https://www.lares.com/blog/from-lares-labs-defensive-guidance-for-zerologon-cve-2020-1472/
  -https://netwrix.com/en/cybersecurity-glossary/cyber-security-attacks/zerologon-vulnerability/
  -https://github.com/sbousseaden/EVTX-ATTACK-SAMPLES/blob/master/Credential%20Access/Zerologon_VoidSec_CVE-2020-1472_4626_LT3_Anonym_follwedby_4742_DC_Anony_DC.evtx
drilldown_searches:
  :
tags:
  analytic_story:
    - 'Detect Zerologon Attack'
  asset_type:Windows
  cve:
    - 'CVE-2020-1472'
  mitre_attack_id:
    - 'T1210'
  product:
    - 'Splunk Enterprise'
    - 'Splunk Enterprise Security'
    - 'Splunk Cloud'
  security_domain:endpoint

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1212/zerologon/zerologon.log
  source: XmlWinEventLog:Security
  sourcetype: XmlWinEventLog
manual_test:None