Potentially Suspicious Event Viewer Child Process

Hunt Hypothesis

Adversaries may leverage suspicious child processes of eventvwr.exe to bypass UAC and execute privileged code, indicating potential elevation of privilege. SOC teams should proactively hunt for

Detection Rule

Sigma (Original)

title: Potentially Suspicious Event Viewer Child Process
id: be344333-921d-4c4d-8bb8-e584cf584780
related:
    - id: 7c81fec3-1c1d-43b0-996a-46753041b1b6
      type: derived
status: test
description: Detects uncommon or suspicious child processes of "eventvwr.exe" which might indicate a UAC bypass attempt
references:
    - https://enigma0x3.net/2016/08/15/fileless-uac-bypass-using-eventvwr-exe-and-registry-hijacking/
    - https://www.hybrid-analysis.com/sample/e122bc8bf291f15cab182a5d2d27b8db1e7019e4e96bb5cdbd1dfe7446f3f51f?environmentId=100
author: Florian Roth (Nextron Systems)
date: 2017-03-19
modified: 2023-09-28
tags:
    - attack.privilege-escalation
    - attack.t1548.002
    - car.2019-04-001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\eventvwr.exe'
    filter_main_generic:
        Image|endswith:
            - ':\Windows\System32\mmc.exe'
            - ':\Windows\System32\WerFault.exe'
            - ':\Windows\SysWOW64\WerFault.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where (ParentProcessName endswith "\\eventvwr.exe" or ActingProcessName endswith "\\eventvwr.exe") and (not((TargetProcessName endswith ":\\Windows\\System32\\mmc.exe" or TargetProcessName endswith ":\\Windows\\System32\\WerFault.exe" or TargetProcessName endswith ":\\Windows\\SysWOW64\\WerFault.exe")))

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Technique: T1548.002 — T1548.002

References

• https://enigma0x3.net/2016/08/15/fileless-uac-bypass-using-eventvwr-exe-and-registry-hijacking/
• https://www.hybrid-analysis.com/sample/e122bc8bf291f15cab182a5d2d27b8db1e7019e4e96bb5cdbd1dfe7446f3f51f?environmentId=100
• SigmaHQ Rule