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Description

The following analytic identifies driver load errors utilizing the Windows PrintService Admin logs. This was identified during our testing of CVE-2021-34527 previously (CVE-2021-1675) or PrintNightmare.
Within the proof of concept code, the following error will occur - “The print spooler failed to load a plug-in module C:\Windows\system32\spool\DRIVERS\x64\3\meterpreter.dll, error code 0x45A. See the event user data for context information.”
The analytic is based on file path and failure to load the plug-in.
During triage, isolate the endpoint and review for source of exploitation. Capture any additional file modification events.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-07-01
  • Author: Mauricio Velazco, Michael Haag, Splunk
  • ID: 1adc9548-da7c-11eb-8f13-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1547.012 Print Processors Persistence, Privilege Escalation
T1547 Boot or Logon Autostart Execution Persistence, Privilege Escalation
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
ID Summary CVSS
CVE-2021-34527 Windows Print Spooler Remote Code Execution Vulnerability 9.0
CVE-2021-1675 Windows Print Spooler Elevation of Privilege Vulnerability 9.3
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2
3
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`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`

Macros

The SPL above uses the following Macros:

Note that print_spooler_failed_to_load_a_plug-in_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • OpCode
  • EventCode
  • ComputerName
  • Message

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.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
72.0 80 90 Suspicious printer spooler errors have occured on endpoint $ComputerName$ with EventCode $EventCode$.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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