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MediumSplunk security contentMauricio Velazco +2

Spoolsv Spawning Rundll32

The following analytic detects the spawning of `rundll32.exe` without command-line arguments by `spoolsv.exe`, which is unusual and potentially indicative of exploitation attempts like CVE-2021-34527…

Description

The following analytic detects the spawning of `rundll32.exe` without command-line arguments by `spoolsv.exe`, which is unusual and potentially indicative of exploitation attempts like CVE-2021-34527 (PrintNightmare). This detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process creation events where `spoolsv.exe` is the parent process. This activity is significant as `spoolsv.exe` typically does not spawn other processes, and such behavior could indicate an active exploitation attempt. If confirmed malicious, this could allow an attacker to execute arbitrary code, escalate privileges, or maintain persistence on the compromised endpoint.

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
crowdstrike_processrollup2sysmon_eventid_1windows_event_log_security_4688

Known benign triggers

  • Limited false positives have been identified. There are limited instances where `rundll32.exe` may be spawned by a legitimate print driver.

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