GitHub Repo

Detection: Splunk HTTP Response Splitting Via Rest SPL Command

REMOVED DETECTION

This detection has been removed from the Splunk Threat Research content library and is no longer maintained or supported.

Reason: Detection is deprecated as the associated CVEs have been patched in the latest Splunk release.

Removed in version: 5.6.0

If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2026-05-14 ID: e615a0e1-a1b2-4196-9865-8aa646e1708c Author: Rod Soto, Chase Franklin Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies attempts to exploit an HTTP response splitting vulnerability via the rest SPL command in Splunk. It detects this activity by analyzing audit logs for specific search commands that include REST methods like POST, PUT, PATCH, or DELETE. This behavior is significant because it indicates a potential attempt to access restricted REST endpoints, which could lead to unauthorized access to sensitive information. If confirmed malicious, this activity could allow an attacker to access restricted content, such as password files, by injecting commands into HTTP requests.

1`audit_searches` AND search IN ("*
2|*rest*POST*","*
3|*rest*PUT*","*
4|*rest*PATCH*","*
5|*rest*DELETE*") AND NOT search="*audit_searches*" 
6| table user info has_error_msg search _time  
7| `splunk_http_response_splitting_via_rest_spl_command_filter`

Data Source

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

Macros Used

Name Value
audit_searches index=_audit sourcetype=audittrail action=search
splunk_http_response_splitting_via_rest_spl_command_filter ``
splunk_http_response_splitting_via_rest_spl_command_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
T1027.006

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule N/A
Earliest Time N/A
Latest Time N/A
Schedule Window N/A
Creates Finding (Notable) No
Creates Intermediate Finding (Risk Event) No
Hunting detections do not generate a Finding (Notable) or Intermediate Findings (Risk Events).

Implementation

This detection does not require you to ingest any new data. The detection does require the ability to search the _audit index. This search may assist in detecting possible http response splitting exploitation attemptss.

Known False Positives

This search may have produce false positives as malformed or erroneous requests made to this endpoint may be executed willingly or erroneously by operators.

Associated Analytic Story

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Not Applicable N/A N/A N/A
Unit Not Applicable 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: 6