ID | Technique | Tactic |
---|---|---|
T1547.012 | Print Processors | Persistence |
T1547 | Boot or Logon Autostart Execution | Privilege Escalation |
Detection: Spoolsv Suspicious Loaded Modules
Description
The following analytic detects the suspicious loading of DLLs by spoolsv.exe, potentially indicating PrintNightmare exploitation. It leverages Sysmon EventCode 7 to identify instances where spoolsv.exe loads multiple DLLs from the Windows System32 spool drivers x64 directory. This activity is significant as it may signify an attacker exploiting the PrintNightmare vulnerability to execute arbitrary code. If confirmed malicious, this could lead to unauthorized code execution, privilege escalation, and persistent access within the environment, posing a severe security risk.
Search
1`sysmon` EventCode=7 Image ="*\\spoolsv.exe" ImageLoaded="*\\Windows\\System32\\spool\\drivers\\x64\\*" ImageLoaded = "*.dll"
2| stats dc(ImageLoaded) as countImgloaded values(ImageLoaded) as ImageLoaded count min(_time) as firstTime max(_time) as lastTime by Image Computer ProcessId EventCode
3| rename Computer as dest
4| where countImgloaded >= 3
5| `security_content_ctime(firstTime)`
6| `security_content_ctime(lastTime)`
7| `spoolsv_suspicious_loaded_modules_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Sysmon EventID 7 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
spoolsv_suspicious_loaded_modules_filter | search * |
spoolsv_suspicious_loaded_modules_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
$Image$ with process id $ProcessId$ has loaded a driver from $ImageLoaded$ on endpoint $dest$. This behavior is suspicious and related to PrintNightmare. | 72 | 80 | 90 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
xmlwineventlog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
xmlwineventlog |
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
Source: GitHub | Version: 3