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29 changes: 29 additions & 0 deletions rules/defense_evasion_clear_eventlog.yml
Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
name: Clear Eventlog
id: 692d3143-e1fb-4dab-8c9c-3109ff80ec85
version: 1.0.0
description: |
Identifies attempts to clear Windows event log stores. Adversaries attempt to evade detection or
destroy forensic evidence on a system to cover their trails and slow down incident response.
labels:
tactic.id: TA0005
tactic.name: Defense Evasion
tactic.ref: https://attack.mitre.org/tactics/TA0005/
technique.id: T1070
technique.name: Indicator Removal
technique.ref: https://attack.mitre.org/techniques/T1070/
subtechnique.id: T1070.001
subtechnique.name: Clear Windows Event Logs
subtechnique.ref: https://attack.mitre.org/techniques/T1070/001/

condition: >
sequence
maxspan 1m
by file.object
|set_file_information and file.info_class = 'EOF' and file.info.eof_size > 50000 and file.name imatches '?:\\Windows\\System32\\winevt\\Logs\\*.evtx'|
|set_file_information and file.info_class = 'Allocation' and file.info.allocation_size > 50000|

output: >
Windows Eventlog store %1.file.name was cleared
severity: high

min-engine-version: 2.3.0
3 changes: 3 additions & 0 deletions rules/macros/macros.yml
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,9 @@
- macro: delete_file
expr: kevt.name = 'DeleteFile'

- macro: set_file_information
expr: kevt.name = 'SetFileInformation'

- macro: query_registry
expr: kevt.name in ('RegQueryKey', 'RegQueryValue') and registry.status = 'Success'

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