WerFault LSASS Process Memory Dump

Status: test
Severity: high
Log source: category file_event, product windows
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects WerFault creating a dump file with a name that indicates that the dump file could be an LSASS process memory, which contains user credentials

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1003.001` OS Credential Dumping: LSASS Memory

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: WerFault LSASS Process Memory Dump
id: c3e76af5-4ce0-4a14-9c9a-25ceb8fda182
status: test
description: Detects WerFault creating a dump file with a name that indicates that the dump file could be an LSASS process memory, which contains user credentials
references:
    - https://github.com/helpsystems/nanodump
author: Florian Roth (Nextron Systems)
date: 2022-06-27
tags:
    - attack.credential-access
    - attack.t1003.001
logsource:
    product: windows
    category: file_event
detection:
    selection:
        Image: C:\WINDOWS\system32\WerFault.exe
        TargetFilename|contains:
            - '\lsass'
            - 'lsass.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Image: C:\WINDOWS\system32\WerFault.exe
    TargetFilename|contains:
        - '\lsass'
        - 'lsass.exe'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Image`	eq	`C:\WINDOWS\system32\WerFault.exe`	`field:"Image" kind:eq value:"C:\WINDOWS\system32\WerFault.exe"`
`TargetFilename`	match	`\lsass` corpus 3 (sigma 3) `lsass.exe`	`field:"TargetFilename" kind:match`