Suspicious NTLM Authentication on the Printer Spooler Service — Sigma Rule

Rule metadata and linked tags

Author: Elastic (idea), Tobias Michalski (Nextron Systems). Source status: test; severity: high. Source dates: 2022-05-04 / 2023-02-09.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 208c3363b657a25be6ff5ae6645478ea1da3f05f82fec5ac3dfb22382ed3e966

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: Suspicious NTLM Authentication on the Printer Spooler Service
id: bb76d96b-821c-47cf-944b-7ce377864492
status: test
description: Detects a privilege elevation attempt by coercing NTLM authentication on the Printer Spooler service
references:
    - https://twitter.com/med0x2e/status/1520402518685200384
    - https://github.com/elastic/detection-rules/blob/dd224fb3f81d0b4bf8593c5f02a029d647ba2b2d/rules/windows/credential_access_relay_ntlm_auth_via_http_spoolss.toml
author: Elastic (idea), Tobias Michalski (Nextron Systems)
date: 2022-05-04
modified: 2023-02-09
tags:
    - attack.privilege-escalation
    - attack.credential-access
    - attack.t1212
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_cli:
        CommandLine|contains|all:
            - 'C:\windows\system32\davclnt.dll,DavSetCookie'
            - 'http'
        CommandLine|contains:
            - 'spoolss'
            - 'srvsvc'
            - '/print/pipe/'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/med0x2e/status/1520402518685200384
• https://github.com/elastic/detection-rules/blob/dd224fb3f81d0b4bf8593c5f02a029d647ba2b2d/rules/windows/credential_access_relay_ntlm_auth_via_http_spoolss.toml