Windows: Uncommon Child Processes Spawned by sigverif.exe

title: "Windows: Uncommon Child Processes Spawned by sigverif.exe"
id: 2a339e7e-aec7-4ec5-86bc-3e974e8b392d
status: test
description: This rule flags process creation events where sigverif.exe spawns a child process that is not one of the explicitly excluded WerFault.exe paths. Attackers may abuse sigverif.exe to blend in with legitimate activity while proxying execution to other binaries. The detection relies on Windows process creation telemetry, matching the parent image ending in \sigverif.exe and filtering out WerFault.exe child processes.
references:
  - https://www.hexacorn.com/blog/2018/04/27/i-shot-the-sigverif-exe-the-gui-based-lolbin/
  - https://twitter.com/0gtweet/status/1457676633809330184
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_sigverif_uncommon_child_process.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-08-19
modified: 2024-08-27
tags:
  - attack.stealth
  - attack.t1216
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|endswith: \sigverif.exe
  filter_main_werfault:
    Image:
      - C:\Windows\System32\WerFault.exe
      - C:\Windows\SysWOW64\WerFault.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: 7d4aaec2-08ed-4430-8b96-28420e030e04
    type: derived