Detect Clear Windows Event Logs in Splunk
Adversaries clear Windows Event Logs to remove evidence of intrusion activity. Primary methods include the wevtutil command-line utility (wevtutil cl system/security/application), the PowerShell Remove-EventLog cmdlet, the Windows Event Viewer GUI, and direct deletion of .evtx log files from C:\Windows\System32\winevt\logs\. When a log is cleared, Windows generates Event ID 1102 (Security log cleared) in the Security log and Event ID 104 (System log cleared) in the System log — but these disappear if the generating log is also cleared. APT28, APT38, APT41, Volt Typhoon, LockBit 2.0/3.0, RansomHub, NotPetya, Olympic Destroyer, BlackCat, and many others routinely clear event logs as post-compromise cleanup.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1070 Indicator Removal
- Sub-technique
- T1070.001 Clear Windows Event Logs
- Canonical reference
- https://attack.mitre.org/techniques/T1070/001/
SPL Detection Query
index=wineventlog (sourcetype="WinEventLog:Security" EventCode=1102) OR (sourcetype="WinEventLog:System" EventCode=104)
| eval LogClearType=case(EventCode=1102, "Security Log Cleared", EventCode=104, "Non-Security Log Cleared", true(), "Unknown")
| table _time, host, user, LogClearType, EventCode
| sort - _time
| append [
search index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
| where (Image like "%wevtutil.exe" AND (match(CommandLine, "(cl |clear-log |clear )")))
OR (Image like "%powershell.exe" AND match(CommandLine, "(Remove-EventLog|Clear-EventLog|wevtutil)"))
| eval LogClearType="Wevtutil/PowerShell Clear Command"
| table _time, host, User, Image, CommandLine, LogClearType
]Detects Security log clearing (Event ID 1102) and other Windows log clearing (Event ID 104) from the respective Windows Event Logs, plus wevtutil.exe and PowerShell-based log clearing commands from Sysmon. Covers both direct Windows event signals and process-level detection for scripted clearing operations.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Scheduled maintenance scripts with admin privileges clearing old logs
- SIEM agents that archive and clear logs after successful forwarding
- Remediation actions by IR teams on compromised systems
- Log management tools that implement retention via clearing
Other platforms for T1070.001
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Clear Security Event Log with wevtutil
Expected signal: Windows Event Log: Security Event ID 1102 (The audit log was cleared) generated just before the log is cleared. Sysmon Event ID 1: wevtutil.exe process creation with 'cl Security' argument. After clearing, the Security log is empty except for the Event ID 4608 (Windows is starting up) that follows a fresh log.
- Test 2Clear Multiple Event Logs Using wevtutil Loop
Expected signal: Multiple Sysmon Event ID 1 events for wevtutil.exe with different log names. Security Event ID 1102 for Security log. System Event ID 104 for each other log cleared. The for loop structure will appear in the parent cmd.exe command line.
- Test 3Clear Event Log via PowerShell Remove-EventLog
Expected signal: PowerShell process creation with Remove-EventLog command. Sysmon Event ID 13 (Registry): removal of the EventLog registry key under HKLM\SYSTEM\CurrentControlSet\Services\EventLog\ArgusTest. System Event ID 104 may be generated for the deleted log.
References (5)
- https://attack.mitre.org/techniques/T1070/001/
- https://docs.microsoft.com/windows-server/administration/windows-commands/wevtutil
- https://docs.microsoft.com/powershell/module/microsoft.powershell.management/clear-eventlog
- https://ptylu.github.io/content/report/report.html?report=25
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1070.001/T1070.001.md
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