Detection: Splunk CSRF in the SSG kvstore Client Endpoint

Date: 2024-07-01 ID: 4742d5f7-ce00-45ce-9c79-5e98b43b4410 Author: Rod Soto Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies attempts to exploit a cross-site request forgery (CSRF) vulnerability in the Splunk Secure Gateway (SSG) app's kvstore_client endpoint. It detects GET requests to the vulnerable endpoint using internal index data, focusing on specific URI paths and HTTP methods. This activity is significant because it can allow unauthorized updates to SSG KV store collections, potentially leading to data manipulation or unauthorized access. If confirmed malicious, this could enable attackers to alter critical configurations or exfiltrate sensitive information, compromising the integrity and security of the Splunk environment.

1`splunkda` uri_path="/*/splunkd/__raw/services/ssg/kvstore_client" method="GET" delete_field_value="spacebridge_server" status="200"  
2| table splunk_server status uri delete_field_value method post_data  
3| `splunk_csrf_in_the_ssg_kvstore_client_endpoint_filter`

Data Source

Name Platform Sourcetype Source Supported App
Splunk Splunk icon Splunk 'splunkd_ui_access' 'splunkd_ui_access.log' N/A

Macros Used

Name Value
splunkda index=_internal sourcetype=splunkd_access
splunk_csrf_in_the_ssg_kvstore_client_endpoint_filter search *
splunk_csrf_in_the_ssg_kvstore_client_endpoint_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
T1189 Drive-by Compromise Initial Access
KillChainPhase.DELIVERY
NistCategory.DE_CM
Cis18Value.CIS_10

Default Configuration

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

Setting Value
Enabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Risk Based Alerting True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

Requires access to internal index.

Known False Positives

This hunting search only applies to the affected versions and setup mentioned in the description of this search, it does not extract payload so it requires manual investigation after executing search. This search will produce false positives.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Potential CSRF exploitation attempt from $splunk_server$ 25 50 50
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 ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset splunkd_access.log splunkd_access
Integration ✅ Passing Dataset splunkd_access.log splunkd_access

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: 3