Windows SystemNightmare Exploitation Attempt via PrintNightmare Command Lines

Alerts on Windows process command lines matching SystemNightmare/PrintNightmare exploitation indicators that may enable LOCAL_SYSTEM shell access.

FreeReviewedSigma · Critical · v5

Product: windows
Category: process_creation
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-08-11
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1068Exploitation for Privilege Escalation
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process creation events whose command line contains strings associated with the SystemNightmare/PrintNightmare exploitation pattern, including the target host and specific username and printer text. Attackers may use this behavior to try to escalate privileges and gain a highly privileged shell. The detection relies on process creation telemetry with a populated command line field.

Reporting behind it

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Windows SystemNightmare Exploitation Attempt via PrintNightmare Command Lines

Pivot detection · T1068 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-systemnightmare-exploitation-attempt-via-printnightmare-cli-indicators-c01f7bd6

title: Windows SystemNightmare Exploitation Attempt via PrintNightmare Command Lines
id: dca4caf4-c981-4955-a768-3fa38f2cd896
status: test
description: This rule flags Windows process creation events whose command line contains strings associated with the SystemNightmare/PrintNightmare exploitation pattern, including the target host and specific username and printer text. Attackers may use this behavior to try to escalate privileges and gain a highly privileged shell. The detection relies on process creation telemetry with a populated command line field.
references:
  - https://github.com/GossiTheDog/SystemNightmare
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2021/Exploits/SystemNightmare-Exploit/proc_creation_win_exploit_other_systemnightmare.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2021-08-11
modified: 2023-02-04
tags:
  - attack.privilege-escalation
  - attack.t1068
  - detection.emerging-threats
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    CommandLine|contains:
      - printnightmare.gentilkiwi.com
      - " /user:gentilguest "
      - Kiwi Legit Printer
  condition: selection
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: c01f7bd6-0c1d-47aa-9c61-187b91273a16
    type: derived

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