HackTool - SharpEvtMute Execution

Hunt Hypothesis

Detects the use of SharpEvtHook, a tool that tampers with the Windows event logs

Detection Rule

Sigma (Original)

title: HackTool - SharpEvtMute Execution
id: bedfc8ad-d1c7-4e37-a20e-e2b0dbee759c
related:
    - id: 49329257-089d-46e6-af37-4afce4290685 # DLL load
      type: similar
status: test
description: Detects the use of SharpEvtHook, a tool that tampers with the Windows event logs
references:
    - https://github.com/bats3c/EvtMute
author: Florian Roth (Nextron Systems)
date: 2022-09-07
modified: 2023-02-14
tags:
    - attack.defense-impairment
    - attack.t1685.001
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        - Image|endswith: '\SharpEvtMute.exe'
        - Description: 'SharpEvtMute'
        - CommandLine|contains:
              - '--Filter "rule '
              - '--Encoded --Filter \"'
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessName endswith "\\SharpEvtMute.exe" or TargetProcessFileDescription =~ "SharpEvtMute" or (TargetProcessCommandLine contains "--Filter \"rule " or TargetProcessCommandLine contains "--Encoded --Filter \\\"")

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Technique: T1685.001 — T1685.001

References

• https://github.com/bats3c/EvtMute
• SigmaHQ Rule