Load Of RstrtMgr.DLL By A Suspicious Process — Sigma Rule

Rule metadata and linked tags

Author: Luc Génaux. Source status: test; severity: high. Source dates: 2023-11-28 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 255bdf1c371a289bd35225247957ac34b58ccc3de5e10d63876665575c464301

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: Load Of RstrtMgr.DLL By A Suspicious Process
id: b48492dc-c5ef-4572-8dff-32bc241c15c8
related:
    - id: 3669afd2-9891-4534-a626-e5cf03810a61
      type: derived
status: test
description: |
    Detects the load of RstrtMgr DLL (Restart Manager) by a suspicious process.
    This library has been used during ransomware campaigns to kill processes that would prevent file encryption by locking them (e.g. Conti ransomware, Cactus ransomware). It has also recently been seen used by the BiBi wiper for Windows.
    It could also be used for anti-analysis purposes by shut downing specific processes.
references:
    - https://www.crowdstrike.com/blog/windows-restart-manager-part-1/
    - https://www.crowdstrike.com/blog/windows-restart-manager-part-2/
    - https://web.archive.org/web/20231221193106/https://www.swascan.com/cactus-ransomware-malware-analysis/
    - https://taiwan.postsen.com/business/88601/Hamas-hackers-use-data-destruction-software-BiBi-which-consumes-a-lot-of-processor-resources-to-wipe-Windows-computer-data--iThome.html
author: Luc Génaux
date: 2023-11-28
tags:
    - attack.impact
    - attack.defense-impairment
    - attack.t1486
    - attack.t1685
logsource:
    category: image_load
    product: windows
detection:
    selection_img:
        - ImageLoaded|endswith: '\RstrtMgr.dll'
        - OriginalFileName: 'RstrtMgr.dll'
    selection_folders_1:
        Image|contains:
            # Note: increase coverage by adding more suspicious paths
            - ':\Perflogs\'
            - ':\Users\Public\'
            - '\Temporary Internet'
    selection_folders_2:
        - Image|contains|all:
              - ':\Users\'
              - '\Favorites\'
        - Image|contains|all:
              - ':\Users\'
              - '\Favourites\'
        - Image|contains|all:
              - ':\Users\'
              - '\Contacts\'
    condition: selection_img and 1 of selection_folders_*
falsepositives:
    - Processes related to software installation
level: high

Original YAML and metadata in JSON

False positives

• Processes related to software installation

Source references

• https://www.crowdstrike.com/blog/windows-restart-manager-part-1/
• https://www.crowdstrike.com/blog/windows-restart-manager-part-2/
• https://web.archive.org/web/20231221193106/https://www.swascan.com/cactus-ransomware-malware-analysis/
• https://taiwan.postsen.com/business/88601/Hamas-hackers-use-data-destruction-software-BiBi-which-consumes-a-lot-of-processor-resources-to-wipe-Windows-computer-data--iThome.html