New Root Certificate Installed Via CertMgr.EXE

Title: New Root Certificate Installed Via CertMgr.EXE
Status: test
Description:Detects execution of "certmgr" with the "add" flag in order to install a new certificate on the system. Adversaries may install a root certificate on a compromised system to avoid warnings when connecting to adversary controlled web servers.
References:
  -https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.004/T1553.004.md
  -https://securelist.com/to-crypt-or-to-mine-that-is-the-question/86307/
Author: oscd.community, @redcanary, Zach Stanford @svch0st
Date: 2023-03-05
modified:None
Tags:

• -'attack.defense-impairment'
• -'attack.t1553.004'

Logsource:

• category: process_creation
• product: windows

Detection:
  selection_img:
Image|endswith:'\CertMgr.exe' OriginalFileName:'CERTMGT.EXE'   selection_cli:
    CommandLine|contains|all:
      -'/add'
      -'root'

  condition:all of selection_*
Falsepositives:
  -Help Desk or IT may need to manually add a corporate Root CA on occasion. Need to test if GPO push doesn't trigger FP
Level: medium