PUA - DefenderCheck Execution — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-08-30 / 2023-02-04.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: b6e5b970a105059b2a56e6d992433b7777044a8fa143ea642bf7b0e6b74b65dc

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PUA - DefenderCheck Execution
id: f0ca6c24-3225-47d5-b1f5-352bf07ecfa7
status: test
description: Detects the use of DefenderCheck, a tool to evaluate the signatures used in Microsoft Defender. It can be used to figure out the strings / byte chains used in Microsoft Defender to detect a tool and thus used for AV evasion.
references:
    - https://github.com/matterpreter/DefenderCheck
author: Florian Roth (Nextron Systems)
date: 2022-08-30
modified: 2023-02-04
tags:
    - attack.stealth
    - attack.t1027.005
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - Image|endswith: '\DefenderCheck.exe'
        - Description: 'DefenderCheck'
    condition: selection
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://github.com/matterpreter/DefenderCheck