Uninstall Sysinternals Sysmon

Hunt Hypothesis

Detects the removal of Sysmon, which could be a potential attempt at defense evasion

Detection Rule

Sigma (Original)

title: Uninstall Sysinternals Sysmon
id: 6a5f68d1-c4b5-46b9-94ee-5324892ea939
status: test
description: Detects the removal of Sysmon, which could be a potential attempt at defense evasion
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md#atomic-test-11---uninstall-sysmon
author: frack113
date: 2022-01-12
modified: 2024-03-13
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection_pe:
        - Image|endswith:
              - \Sysmon64.exe
              - \Sysmon.exe
        - Description: 'System activity monitor'
    selection_cli:
        CommandLine|contains|windash: '-u'
    condition: all of selection_*
falsepositives:
    - Legitimate administrators might use this command to remove Sysmon for debugging purposes
level: high

KQL (Azure Sentinel)

imProcessCreate
| where ((TargetProcessName endswith "\\Sysmon64.exe" or TargetProcessName endswith "\\Sysmon.exe") or TargetProcessFileDescription =~ "System activity monitor") and (TargetProcessCommandLine contains "-u" or TargetProcessCommandLine contains "/u" or TargetProcessCommandLine contains "–u" or TargetProcessCommandLine contains "—u" or TargetProcessCommandLine contains "―u")

Required Data Sources

False Positive Guidance

• Legitimate administrators might use this command to remove Sysmon for debugging purposes

MITRE ATT&CK Context

• Technique: T1685 — T1685

References

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md#atomic-test-11---uninstall-sysmon
• SigmaHQ Rule