Print Spooler Failed to Load a Plug-in

name: Print Spooler Failed to Load a Plug-in
id: 1adc9548-da7c-11eb-8f13-acde48001122
version: 8
date: '2026-03-10'
author: Mauricio Velazco, Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects driver load errors in the Windows PrintService Admin logs, specifically identifying issues related to CVE-2021-34527 (PrintNightmare). It triggers on error messages indicating the print spooler failed to load a plug-in module, such as "meterpreter.dll," with error code 0x45A. This detection method leverages specific event codes and error messages. This activity is significant as it may indicate an exploitation attempt of a known vulnerability. If confirmed malicious, an attacker could gain unauthorized code execution on the affected system, leading to potential system compromise.
data_source:
    - Windows Event Log Printservice 808
    - Windows Event Log Printservice 4909
search: '`printservice` ((ErrorCode="0x45A" (EventCode="808" OR EventCode="4909")) OR ("The print spooler failed to load a plug-in module" OR "\\drivers\\x64\\")) | stats count min(_time) as firstTime max(_time) as lastTime by OpCode EventCode ComputerName Message | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `print_spooler_failed_to_load_a_plug_in_filter`'
how_to_implement: You will need to ensure PrintService Admin and Operational logs are being logged to Splunk from critical or all systems.
known_false_positives: False positives are unknown and filtering may be required.
references:
    - https://www.truesec.com/hub/blog/fix-for-printnightmare-cve-2021-1675-exploit-to-keep-your-print-servers-running-while-a-patch-is-not-available
    - https://www.truesec.com/hub/blog/exploitable-critical-rce-vulnerability-allows-regular-users-to-fully-compromise-active-directory-printnightmare-cve-2021-1675
    - https://www.reddit.com/r/msp/comments/ob6y02/critical_vulnerability_printnightmare_exposes
drilldown_searches:
    - name: View the detection results for - "$ComputerName$"
      search: '%original_detection_search% | search  ComputerName = "$ComputerName$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$ComputerName$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$ComputerName$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: Suspicious printer spooler errors have occurred on endpoint $ComputerName$ with EventCode $EventCode$.
    risk_objects:
        - field: ComputerName
          type: system
          score: 50
    threat_objects: []
tags:
    analytic_story:
        - PrintNightmare CVE-2021-34527
        - Black Basta Ransomware
    asset_type: Endpoint
    cve:
        - CVE-2021-34527
        - CVE-2021-1675
    mitre_attack_id:
        - T1547.012
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1547.012/printnightmare/windows-printservice_admin.log
          source: WinEventLog:Microsoft-Windows-PrintService/Admin
          sourcetype: WinEventLog