splunk-security_content/docs/_posts/2021-07-01-spoolsv_suspicious_loaded_modules.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Spoolsv Suspicious Loaded Modules	Print Processors, Boot or Logon Autostart Execution	Endpoint	2021-07-01	true		Print Processors Persistence Privilege Escalation Boot or Logon Autostart Execution Persistence Privilege Escalation Splunk Enterprise Splunk Enterprise Security Splunk Cloud CVE-2021-34527 Endpoint

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Description

This search is to detect suspicious loading of dll in specific path relative to printnightmare exploitation. In this search we try to detect the loaded modules made by spoolsv.exe after the exploitation.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-07-01
• Author: Mauricio Velazco, Michael Haag, Teoderick Contreras, Splunk
• ID: a5e451f8-da81-11eb-b245-acde48001122

ATT&CK

ID	Technique	Tactic
T1547.012	Print Processors	Persistence, Privilege Escalation

| T1547 | Boot or Logon Autostart Execution | Persistence, Privilege Escalation |

Search

`sysmon` EventCode=7 Image ="*\\spoolsv.exe" ImageLoaded="*\\Windows\\System32\\spool\\drivers\\x64\\*" ImageLoaded = "*.dll" 
| stats dc(ImageLoaded) as countImgloaded values(ImageLoaded) as ImgLoaded count min(_time) as firstTime max(_time) as lastTime by Image Computer process_id EventCode 
| where countImgloaded >= 3 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `spoolsv_suspicious_loaded_modules_filter`

Associated Analytic Story

• PrintNightmare CVE-2021-34527

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and imageloaded executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Required field

• _time
• Image
• Computer
• EventCode
• ImageLoaded

Kill Chain Phase

• Exploitation

Known False Positives

unknown

RBA

Risk Score	Impact	Confidence	Message
72.0	80	90	Image with process id process_id has loaded a driver from ImageLoaded on endpoint Computer. This behavior is suspicious and related to PrintNightmare.

CVE

ID	Summary	CVSS
CVE-2021-34527	Windows Print Spooler Remote Code Execution Vulnerability	9.0

Reference

• https://raw.githubusercontent.com/hieuttmmo/sigma/dceb13fe3f1821b119ae495b41e24438bd97e3d0/rules/windows/image_load/sysmon_cve_2021_1675_print_nightmare.yml

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1547.012/printnightmare/windows-sysmon.log

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