Detectionmediumtest

New Root Certificate Installed Via Certutil.EXE

Detects execution of "certutil" with the "addstore" 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.

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Launch
oscd.community, Zach StanfordCreated Sun Mar 05Updated Tue Mar 05d2125259-ddea-4c1c-9c22-977eb5b29cf0windows
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic
Detection Logic3 selectors
detection:
    # Example: certutil -addstore -f -user ROOT CertificateFileName.der
    selection_img:
        - Image|endswith: '\certutil.exe'
        - OriginalFileName: 'CertUtil.exe'
    selection_cli_add:
        CommandLine|contains|windash: '-addstore'
    selection_cli_store:
        CommandLine|contains: 'root'
    condition: all of selection_*
False Positives

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

Testing & Validation

Regression Tests

by SigmaHQ Team
Positive Detection Test1 matchevtx

Microsoft-Windows-Sysmon

Rule Metadata
Rule ID
d2125259-ddea-4c1c-9c22-977eb5b29cf0
Status
test
Level
medium
Type
Detection
Created
Sun Mar 05
Modified
Tue Mar 05
Path
rules/windows/process_creation/proc_creation_win_certutil_certificate_installation.yml
Raw Tags
attack.defense-evasionattack.t1553.004
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