Sunturai
Back to results
MediumSplunk security contentMauricio Velazco +2

Spoolsv Writing a DLL

The following analytic detects `spoolsv.exe` writing a `.dll` file, which is unusual behavior and may indicate exploitation of vulnerabilities like CVE-2021-34527 (PrintNightmare). This detection leverages the…

Description

The following analytic detects `spoolsv.exe` writing a `.dll` file, which is unusual behavior and may indicate exploitation of vulnerabilities like CVE-2021-34527 (PrintNightmare). This detection leverages the Endpoint datamodel, specifically monitoring process and filesystem events to identify `.dll` file creation within the `\spool\drivers\x64\` path. This activity is significant as it may signify an attacker attempting to execute malicious code via the Print Spooler service. If confirmed malicious, this could lead to unauthorized code execution and potential system compromise. Immediate endpoint isolation and further investigation are recommended.

Detection logic

Detection requirements

Platform
Windows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source category
sysmon_eventid_1_and_sysmon_eventid_11windows_event_log_security_4688_and_sysmon_eventid_11

Known benign triggers

  • No false positives have been identified at this time.

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice