Credential Dumping Attempt Via WerFault

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

Detects process LSASS memory dump using Mimikatz, NanoDump, Invoke-Mimikatz, Procdump or Taskmgr based on the CallTrace pointing to ntdll.dll, dbghelp.dll or dbgcore.dll for win10, server2016 and up.

Known false positives

Actual failures in lsass.exe that trigger a crash dump (unlikely)
Unknown cases in which WerFault accesses lsass.exe

MITRE ATT&CK coverage

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

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 10: ProcessAccess

Rule body

title: Credential Dumping Attempt Via WerFault
id: e5b33f7d-eb93-48b6-9851-09e1e610b6d7
status: test
description: Detects process LSASS memory dump using Mimikatz, NanoDump, Invoke-Mimikatz, Procdump or Taskmgr based on the CallTrace pointing to ntdll.dll, dbghelp.dll or dbgcore.dll for win10, server2016 and up.
references:
    - https://github.com/helpsystems/nanodump/commit/578116faea3d278d53d70ea932e2bbfe42569507
author: Florian Roth (Nextron Systems)
date: 2012-06-27
modified: 2023-11-29
tags:
    - attack.credential-access
    - attack.t1003.001
    - attack.s0002
logsource:
    category: process_access
    product: windows
detection:
    selection:
        SourceImage|endswith: '\WerFault.exe'
        TargetImage|endswith: '\lsass.exe'
        GrantedAccess: '0x1FFFFF'
    condition: selection
falsepositives:
    - Actual failures in lsass.exe that trigger a crash dump (unlikely)
    - Unknown cases in which WerFault accesses lsass.exe
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    SourceImage|endswith: '\WerFault.exe'
    TargetImage|endswith: '\lsass.exe'
    GrantedAccess: '0x1FFFFF'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`GrantedAccess`	eq	`0x1FFFFF` corpus 9 (sigma 7, splunk 1, kusto 1)	`field:"GrantedAccess" kind:eq value:"0x1FFFFF"`
`SourceImage`	ends_with	`\WerFault.exe`	`field:"SourceImage" kind:ends_with value:"\WerFault.exe"`
`TargetImage`	ends_with	`\lsass.exe` corpus 16 (sigma 16)	`field:"TargetImage" kind:ends_with value:"\lsass.exe"`