LSASS Access Detected via Attack Surface Reduction — Sigma Rule

Rule metadata and linked tags

Author: Markus Neis. Source status: test; severity: high. Source dates: 2018-08-26 / 2022-08-13.

{
  "product": "windows",
  "service": "windefend",
  "definition": "Requirements:Enabled Block credential stealing from the Windows local security authority subsystem (lsass.exe) from Attack Surface Reduction (GUID: 9e6c4e1f-7d60-472f-ba1a-a39ef669e4b2)"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0348816ebc3d42c5d78b07692445a356b7cd0a2d49195387be0bc86c02c6239d

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 Access Detected via Attack Surface Reduction
id: a0a278fe-2c0e-4de2-ac3c-c68b08a9ba98
status: test
description: Detects Access to LSASS Process
references:
    - https://learn.microsoft.com/en-us/defender-endpoint/attack-surface-reduction
author: Markus Neis
date: 2018-08-26
modified: 2022-08-13
tags:
    - attack.credential-access
    - attack.t1003.001
logsource:
    product: windows
    service: windefend
    definition: 'Requirements:Enabled Block credential stealing from the Windows local security authority subsystem (lsass.exe) from Attack Surface Reduction (GUID: 9e6c4e1f-7d60-472f-ba1a-a39ef669e4b2)'
detection:
    selection:
        EventID: 1121
        Path|endswith: '\lsass.exe'
    filter_thor:
        ProcessName|startswith: 'C:\Windows\Temp\asgard2-agent\'
        ProcessName|endswith:
            - '\thor64.exe'
            - '\thor.exe'
    filter_exact:
        ProcessName:
            - 'C:\Windows\System32\atiesrxx.exe'
            - 'C:\Windows\System32\CompatTelRunner.exe'
            - 'C:\Windows\System32\msiexec.exe'
            - 'C:\Windows\System32\nvwmi64.exe'
            - 'C:\Windows\System32\svchost.exe'
            - 'C:\Windows\System32\Taskmgr.exe'
            - 'C:\Windows\System32\wbem\WmiPrvSE.exe'
            - 'C:\Windows\SysWOW64\msiexec.exe'
    filter_begins:
        ProcessName|startswith:
            - 'C:\Windows\System32\DriverStore\'
            - 'C:\WINDOWS\Installer\'
            - 'C:\Program Files\'
            - 'C:\Program Files (x86)\'
    condition: selection and not 1 of filter_*
falsepositives:
    - Google Chrome GoogleUpdate.exe
    - Some Taskmgr.exe related activity
level: high

Original YAML and metadata in JSON

False positives

• Google Chrome GoogleUpdate.exe
• Some Taskmgr.exe related activity

Source references

• https://learn.microsoft.com/en-us/defender-endpoint/attack-surface-reduction