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Detection rules › Sigma

Lsass Memory Dump via Comsvcs DLL

Status
test
Severity
high
Log source
category process_access, product windows
Author
Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
Source
github.com/SigmaHQ/sigma

Detects adversaries leveraging the MiniDump export function from comsvcs.dll via rundll32 to perform a memory dump from lsass.

MITRE ATT&CK coverage

TacticTechniques
Credential Access

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 10: ProcessAccess

Rule body

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

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    TargetImage|endswith: '\lsass.exe'
    SourceImage|endswith: '\rundll32.exe'
    CallTrace|contains: 'comsvcs.dll'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CallTracematch
  • comsvcs.dll
field:"CallTrace" kind:match value:"comsvcs.dll"
SourceImageends_with
  • \rundll32.exe
field:"SourceImage" kind:ends_with value:"\rundll32.exe"
TargetImageends_with
  • \lsass.exe corpus 16 (sigma 16)
field:"TargetImage" kind:ends_with value:"\lsass.exe"