Suspicious Rejected SMB Guest Logon From IP — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), KevTheHermit, fuzzyf10w. Source status: test; severity: medium. Source dates: 2021-06-30 / 2023-01-02.

{
  "product": "windows",
  "service": "smbclient-security"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 154276760f04f84791877b781d2c00edaf9a13d91add988306bb683843267427

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 Rejected SMB Guest Logon From IP
id: 71886b70-d7b4-4dbf-acce-87d2ca135262
status: test
description: Detect Attempt PrintNightmare (CVE-2021-1675) Remote code execution in Windows Spooler Service
references:
    - https://twitter.com/KevTheHermit/status/1410203844064301056
    - https://web.archive.org/web/20210629055600/https://github.com/hhlxf/PrintNightmare/
    - https://web.archive.org/web/20210701042336/https://github.com/afwu/PrintNightmare
author: Florian Roth (Nextron Systems), KevTheHermit, fuzzyf10w
date: 2021-06-30
modified: 2023-01-02
tags:
    - attack.credential-access
    - attack.t1110.001
logsource:
    product: windows
    service: smbclient-security
detection:
    selection:
        EventID: 31017
        UserName: ''
        ServerName|startswith: '\1'
    condition: selection
falsepositives:
    - Account fallback reasons (after failed login with specific account)
level: medium

Original YAML and metadata in JSON

False positives

• Account fallback reasons (after failed login with specific account)

Source references

• https://twitter.com/KevTheHermit/status/1410203844064301056
• https://web.archive.org/web/20210629055600/https://github.com/hhlxf/PrintNightmare/
• https://web.archive.org/web/20210701042336/https://github.com/afwu/PrintNightmare