Name:Suspicious Computer Account Name Change id:35a61ed8-61c4-11ec-bc1e-acde48001122 version:5 date:2024-11-28 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 ("$dest$", "$OldTargetUserName$") starthoursago=168 | 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:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Active Directory Privilege Escalation' - 'Compromised Windows Host' - 'sAMAccountName Spoofing and Domain Controller Impersonation' asset_type:Endpoint confidence:70 cve: - 'CVE-2021-42287' - 'CVE-2021-42278' impact:100 message:A computer account $OldTargetUserName$ was renamed with a suspicious computer name on $dest$ mitre_attack_id: - 'T1078' - 'T1078.002' observable: name:'dest' type:'Endpoint' - role: - 'Victim' name:'OldTargetUserName' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'Computer' - 'Caller_User_Name' - 'OldTargetUserName' - 'NewTargetUserName' risk_score:70 security_domain:endpoint
