Name:Windows Eventlog Cleared Via Wevtutil id:fdb829a8-db84-4832-b64b-3e964cd44f01 version:8 date:None author:Nasreddine Bencherchali, Splunk status:production type:Anomaly Description:The following analytic detects the usage of wevtutil.exe with the "clear-log" parameter in order to clear the contents of logs.
Clearing the event logs can be an attempt to cover tracks after malicious actions, hindering forensic investigations.
Data_source:
-Sysmon EventID 1
-Windows Event Log Security 4688
-CrowdStrike ProcessRollup2
search:| tstats `security_content_summariesonly` count values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime
FROM datamodel=Endpoint.Processes WHERE
Processes.process_name=wevtutil.exe Processes.process IN ("* cl *", "*clear-log*")
``` We exclude the following strings to avoid detection overlap and double coverage since they are already covered by the "Suspicious wevtutil Usage" detection. ``` NOT Processes.process IN ( "*/Trace*", "*AMSI/Debug*", "*Application*", "*CiscoSecureEndpoint*", "*Microsoft-Windows-BitLocker*", "*Microsoft-Windows-Bits*", "*Microsoft-Windows-CAPI2*", "*Microsoft-Windows-Kernel-File*", "*Microsoft-Windows-Kernel-Process*", "*Microsoft-Windows-LDAP*", "*Microsoft-Windows-PowerShell*", "*Microsoft-Windows-Sysmon*", "*Microsoft-Windows-TerminalServices-LocalSessionManager*", "*Microsoft-Windows-TerminalServices-RemoteConnectionManager*", "*Microsoft-Windows-WMI-Activity*", "*OpenSSH/*", "*PowerShellCore/*", "*Security*", "*Setup*", "*System*", "*Windows Firewall With Advanced Security*", "*Windows PowerShell*" )
how_to_implement:The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process. known_false_positives:The wevtutil.exe application is a legitimate Windows event log utility. Administrators may use it to manage Windows event logs. References: -https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1070.001/T1070.001.md drilldown_searches: name:'View the detection results for - "$dest$" and "$user$"' search:'%original_detection_search% | search dest = "$dest$" user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$" and "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") | 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' analytic_story:['Windows Log Manipulation', 'Ransomware', 'Rhysida Ransomware', 'Clop Ransomware', 'CISA AA23-347A', 'ShrinkLocker']
