Print Spooler Failed to Load a Plug-in

name: Print Spooler Failed to Load a Plug-in
id: 1adc9548-da7c-11eb-8f13-acde48001122
version: 10
creation_date: '2021-07-01'
modification_date: '2026-05-13'
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
finding:
    title: Suspicious printer spooler errors have occurred on endpoint $ComputerName$ with EventCode $EventCode$.
    entity:
        field: ComputerName
        type: system
        score: 50
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
category: endpoint
security_domain: endpoint