Detect Computer Changed with Anonymous Account
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.
Query · spl
`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`
Implementation guide
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.
Analyst notes
Known false positives: Some legitimate, legacy devices may utilize this functionality and generate false positives. Apply additional tuning as needed.