LSASS credential dump with LSASSY (PowerShell)

Status: experimental
Severity: medium
Log source: category ['ps_module', 'ps_classic_script', 'ps_script'], product windows
Author: mdecrevoisier
Source: github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker remotely dump LSASS credentials using the LSASSY tool.

Known false positives

legitimate administrator activation

MITRE ATT&CK coverage

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

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4103: Payload Context: ContextInfo User Data: UserData.
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).
PowerShell	Event ID 800

Rule body

title: LSASS credential dump with LSASSY (PowerShell)
description: Detects scenarios where an attacker remotely dump LSASS credentials using the LSASSY tool.
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0006-Credential%20Access/T1003-Credential%20dumping
- https://github.com/Hackndo/lsassy
tags:
- attack.credential_access
- attack.t1003.001
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  category:
    - ps_module
    - ps_classic_script
    - ps_script
detection: # full command: 'C:\Windows\System32\rundll32.exe C:\Windows\System32\comsvcs.dll, MiniDump (Get-Process lsass).Id \Windows\Temp\vtnr8kff.dmp full;Wait-Process -Id (Get-Process rundll32).id'
  selection_powershell_native:
    EventID: 800
    EventData|contains|all:
      - rundll32.exe
      - comsvcs.dll
      - lsass
      #- '.dmp' # Extension can be changed in source code

  selection_powershell_modern:
    EventID: 4103
    Payload|contains|all:
      - rundll32.exe
      - comsvcs.dll
      - lsass
      #- '.dmp' # Extension can be changed in source code

  selection_powershell_block:
    EventID: 4104
    ScriptBlockText|contains|all:
      - rundll32.exe
      - comsvcs.dll
      - lsass
      #- '.dmp' # Extension can be changed in source code

  condition: 1 of selection*
falsepositives:
- legitimate administrator activation
level: medium

Stages and Predicates

Stage 0: `condition`

1 of selection*

Stage 1: `selection_powershell_native`

selection_powershell_native:
  EventID: 800
  EventData|contains|all:
    - rundll32.exe
    - comsvcs.dll
    - lsass

Stage 2: `selection_powershell_modern`

selection_powershell_modern:
  EventID: 4103
  Payload|contains|all:
    - rundll32.exe
    - comsvcs.dll
    - lsass

Stage 3: `selection_powershell_block`

selection_powershell_block:
  EventID: 4104
  ScriptBlockText|contains|all:
    - rundll32.exe
    - comsvcs.dll
    - lsass

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventData`	match	`comsvcs.dll` `lsass` `rundll32.exe` corpus 2 (sigma 1, kusto 1)	`field:"EventData" kind:match`
`Payload`	match	`comsvcs.dll` `lsass` `rundll32.exe` corpus 2 (sigma 2)	`field:"Payload" kind:match`
`ScriptBlockText`	match	`comsvcs.dll` `lsass` `rundll32.exe` corpus 2 (sigma 2)	`field:"ScriptBlockText" kind:match`

LSASS credential dump with LSASSY (PowerShell)

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_powershell_native

Stage 2: selection_powershell_modern

Stage 3: selection_powershell_block

Indicators

Stage 0: `condition`

Stage 1: `selection_powershell_native`

Stage 2: `selection_powershell_modern`

Stage 3: `selection_powershell_block`