Detection: Splunk App for Lookup File Editing RCE via User XSLT

EXPERIMENTAL DETECTION

This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-05-16 ID: a053e6a6-2146-483a-9798-2d43652f3299 Author: Rod Soto, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies the creation of lookup files in Splunk, which could indicate an attempt to exploit remote code execution via user-supplied XSLT. It leverages REST API queries to monitor the creation of these lookups, focusing on fields such as title, author, and access control lists. This activity is significant because it targets a known vulnerability in Splunk versions 9.1.x, potentially allowing attackers to execute arbitrary code. If confirmed malicious, this could lead to unauthorized code execution, compromising the integrity and security of the Splunk environment.

1
2| rest splunk_server=local /services/data/lookup-table-files/ 
3| fields title author disabled eai:acl.app eai:acl.owner eai:acl.sharing eai:appName eai:data 
4| `splunk_app_for_lookup_file_editing_rce_via_user_xslt_filter`

Data Source

Name Platform Sourcetype Source Supported App
N/A N/A N/A N/A N/A

Macros Used

Name Value

| splunk_app_for_lookup_file_editing_rce_via_user_xslt_filter | search * |

splunk_app_for_lookup_file_editing_rce_via_user_xslt_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1210 Exploitation of Remote Services Lateral Movement
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
APT28
Dragonfly
Earth Lusca
FIN7
Fox Kitten
MuddyWater
Threat Group-3390
Tonto Team
Wizard Spider
menuPass

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 Risk Event False
This configuration file applies to all detections of type hunting.

Implementation

Because there is no way to detect the payload, this search only provides the ability to monitor the creation of lookups which are the base of this exploit. An operator must then investigate suspicious lookups. This search requires ability to perform REST queries. Note that if the Splunk App for Lookup File Editing is not, or was not, installed in the Splunk environment then it is not necessary to run the search as the enviornment was not vulnerable.

Known False Positives

This search will provide information for investigation and hunting of lookup creation via user-supplied XSLT which may be indications of possible exploitation. There will be false positives as it is not possible to detect the payload executed via this exploit.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Please review $eai:acl.app$ for possible malicious lookups 1 50 2
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Not Applicable N/A N/A N/A
Unit ❌ Failing N/A N/A N/A
Integration ❌ Failing N/A N/A N/A

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: 2