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Description

This search provides information to investigate possible remote code execution exploitation via user-supplied Extensible Stylesheet Language Transformations (XSLT), affecting Splunk versions 9.1.x.

  • Type: Hunting

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-11-22
  • Author: Marissa Bower, Chase Franklin, Rod Soto, Bhavin Patel, Eric McGinnis, Splunk
  • ID: 6cb7e011-55fb-48e3-a98d-164fa854e37e

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1210 Exploitation of Remote Services Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE
ID Summary CVSS
    


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`splunkd_ui` ((uri="*NO_BINARY_CHECK=1*" AND "*input.path=*.xsl*") OR uri="*dispatch*.xsl*") AND uri!= "*splunkd_ui*" 
| rex field=uri "(?<string>=\s*([\S\s]+))" 
| eval decoded_field=urldecode(string) 
| eval action=case(match(status,"200"),"Allowed",match(status,"303
|500
|401
|403
|404
|301
|406"),"Blocked",1=1,"Unknown") 
| stats count min(_time) as firstTime max(_time) as lastTime by clientip useragent uri decoded_field action host 
| rename clientip as src, uri as dest_uri 
| iplocation src 
| fillnull value="N/A" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| table firstTime, lastTime src, useragent, action, count, Country, Region, City, dest_uri, decoded_field

Macros

The SPL above uses the following Macros:

:information_source: splunk_rce_via_user_xslt_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.

  • uri
  • clientip
  • useragent
  • action
  • host

How To Implement

This detection does not require you to ingest any new data. The detection does require the ability to search the _internal index.

Known False Positives

This search will provide information for investigation and hunting possible abuse of user-supplied XSLT. There may be false positives and results should individually evaluated. Please evaluate the source IP and useragent responsible for creating the requests.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 Potential Remote Code Execution via XLST from $src$ using useragent - $useragent$

:information_source: 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: 1