Lsass Memory Dump via Comsvcs DLL — Sigma Rule

Rule metadata and linked tags

Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research). Source status: test; severity: high. Source dates: 2020-10-20 / 2023-11-29.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: f5d1a158c4cce63db599f3ce4f231769304f3c7cbbc4909e25bf833028524e67

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: Lsass Memory Dump via Comsvcs DLL
id: a49fa4d5-11db-418c-8473-1e014a8dd462
status: test
description: Detects adversaries leveraging the MiniDump export function from comsvcs.dll via rundll32 to perform a memory dump from lsass.
references:
    - https://twitter.com/shantanukhande/status/1229348874298388484
    - https://modexp.wordpress.com/2019/08/30/minidumpwritedump-via-com-services-dll/
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
date: 2020-10-20
modified: 2023-11-29
tags:
    - attack.credential-access
    - attack.t1003.001
logsource:
    category: process_access
    product: windows
detection:
    selection:
        TargetImage|endswith: '\lsass.exe'
        SourceImage|endswith: '\rundll32.exe'
        CallTrace|contains: 'comsvcs.dll'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/shantanukhande/status/1229348874298388484
• https://modexp.wordpress.com/2019/08/30/minidumpwritedump-via-com-services-dll/