Unusual AppCert Child Process (Sysmon)

id: '35215.61888'
title: Unusual AppCert Child Process
description: Threat actors may exploit legitimate developer utilities to execute malicious
  payloads by proxy. One such utility is appcert.exe, a command-line tool included
  in the Windows Application Certification Kit, which is typically used to verify
  the compliance of Windows applications with Microsoft's certification standards.
  This use case detects appcert launching child processes outside of known good paths
  C:\Program Files\Windows Kits\10\App Certification Kit\ and C:\Program Files (x86)\Windows
  Kits\10\App Certification Kit\. Living Off the Land Binary and Scripts (LOLBAS)
  (LOLBIN)
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<")
  (TERM(appcert) OR "appcert.exe") | regex parent_process_name="(?i)^appcert.exe"|
  regex process_path!="(?i)\x5cProgram\sFiles(\s\(x86\))?\x5cWindows\sKits\x5c10\x5c"
  | table _time, host, user, process, signature_id, parent_process_*, process_* |
  bin span=1s | stats values(*) as * by _time, host '
techniques:
- defense-evasion:trusted developer utilities proxy execution
technique_id: 
- T1127
data_category:
- Windows Sysmon
references:
- https://attack.mitre.org/techniques/T1127/
- https://attack.mitre.org/techniques/T1218/007/
- https://lolbas-project.github.io/lolbas/OtherMSBinaries/Appcert/