---
title: "Spoolsv Suspicious Loaded Modules"
excerpt: "Print Processors, Boot or Logon Autostart Execution"
categories:
  - Endpoint
last_modified_at: 2021-07-01
toc: true
toc_label: ""
tags:
  - 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](https://github.com/splunk/security_content/wiki/Detection-Analytic-Types)
- **Product**: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- **Datamodel**: [Endpoint](https://docs.splunk.com/Documentation/CIM/latest/User/Endpoint)
- **Last Updated**: 2021-07-01
- **Author**: Mauricio Velazco, Michael Haag, Teoderick Contreras, Splunk
- **ID**: a5e451f8-da81-11eb-b245-acde48001122


#### [ATT&CK](https://attack.mitre.org/)

| ID             | Technique        |  Tactic             |
| -------------- | ---------------- |-------------------- |
| [T1547.012](https://attack.mitre.org/techniques/T1547/012/) | Print Processors | Persistence, Privilege Escalation |

| [T1547](https://attack.mitre.org/techniques/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`
```

#### Macros
The SPL above uses the following Macros:
* [security_content_ctime](https://github.com/splunk/security_content/blob/develop/macros/security_content_ctime.yml)
* [sysmon](https://github.com/splunk/security_content/blob/develop/macros/sysmon.yml)

Note that `spoolsv_suspicious_loaded_modules_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
* Image
* Computer
* EventCode
* ImageLoaded


#### 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.

#### Known False Positives
unknown

#### Associated Analytic story
* [PrintNightmare CVE-2021-34527](/stories/printnightmare_cve-2021-34527)


#### Kill Chain Phase
* Exploitation



#### 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. |


Note that risk score is calculated base on the following formula: `(Impact * Confidence)/100`


#### CVE

| ID          | Summary | [CVSS](https://nvd.nist.gov/vuln-metrics/cvss) |
| ----------- | ----------- | -------------- |
| [CVE-2021-34527](https://nvd.nist.gov/vuln/detail/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](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`](https://github.com/splunk/attack_data#using-replaypy) tool or the [UI](https://github.com/splunk/attack_data#using-ui).
Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)

* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1547.012/printnightmare/windows-sysmon.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1547.012/printnightmare/windows-sysmon.log)



[*source*](https://github.com/splunk/security_content/tree/develop/detections/endpoint/spoolsv_suspicious_loaded_modules.yml) \| *version*: **1**