Detection: Splunk RCE via Serialized Session Payload

Updated Date: 2025-01-21 ID: d1d8fda6-874a-400f-82cf-dcbb59d8e4db Author: Chase Franklin, Rod Soto, Eric McGinnis, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the execution of a specially crafted query using the 'collect' SPL command in Splunk Enterprise versions lower than 8.2.12, 9.0.6, and 9.1.1. It leverages audit logs to identify searches containing both 'makeresults' and 'collect' commands. This activity is significant because it can indicate an attempt to serialize untrusted data, potentially leading to arbitrary code execution. If confirmed malicious, this could allow an attacker to execute code within the Splunk environment, leading to unauthorized access and control over the system.

Search

1`audit_searches` file=* (search="*makeresults*" AND search="*collect*") 
2| stats count min(_time) as firstTime max(_time) as lastTime by action file user splunk_server search 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `splunk_rce_via_serialized_session_payload_filter`

Data Source

Name	Platform	Sourcetype	Source
Splunk	Splunk	`'splunkd_ui_access'`	`'splunkd_ui_access.log'`

Macros Used

Name	Value
audit_searches	`index=_audit sourcetype=audittrail action=search`
splunk_rce_via_serialized_session_payload_filter	`search *`

splunk_rce_via_serialized_session_payload_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
T1190	Exploit Public-Facing Application	Initial Access

Delivery

DE.AE

CIS 10

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

Requires access to the _audit index.

Known False Positives

There are numerous many uses of the 'makeresults' and 'collect' SPL commands. Please evaluate the results of this search for potential abuse.

Associated Analytic Story

Splunk Vulnerabilities

References

https://www.splunk.com/en_us/product-security.html

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`audittrail`	`audittrail`
Integration	✅ Passing	Dataset	`audittrail`	`audittrail`

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: 4