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.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2024-05-23
- Author: Mauricio Velazco, Michael Haag, Teoderick Contreras, Splunk
- ID: a5e451f8-da81-11eb-b245-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Installation
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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`sysmon` EventCode=7 Image ="*\\spoolsv.exe" ImageLoaded="*\\Windows\\System32\\spool\\drivers\\x64\\*" ImageLoaded = "*.dll"
| stats dc(ImageLoaded) as countImgloaded values(ImageLoaded) as ImageLoaded count min(_time) as firstTime max(_time) as lastTime by Image Computer ProcessId EventCode
| rename Computer as dest
| where countImgloaded >= 3
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `spoolsv_suspicious_loaded_modules_filter`
Macros
The SPL above uses the following Macros:
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 fields
List of fields required to use this analytic.
- _time
- Image
- dest
- 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
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
72.0 | 80 | 90 | $Image$ with process id $ProcessId$ has loaded a driver from $ImageLoaded$ on endpoint $dest$. This behavior is suspicious and related to PrintNightmare. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
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
source | version: 3