Detection: Splunk ES DoS Investigations Manager via Investigation Creation

Updated Date: 2024-05-25 ID: 7f6a07bd-82ef-46b8-8eba-802278abd00e Author: Rod Soto, Eric McGinnis, Chase Franklin Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation of malformed Investigations in Splunk Enterprise Security (ES) versions lower than 7.1.2, which can lead to a denial of service (DoS). It leverages internal Splunk logs, specifically monitoring the splunkd_investigation_rest_handler with error statuses during investigation creation. This activity is significant as it can disrupt the functionality of the Investigations manager, hindering incident response efforts. If confirmed malicious, this could prevent security teams from accessing critical investigation data, severely impacting their ability to manage and respond to security incidents effectively.

1`splunkd_investigation_rest_handler` method=put msg=*investigation* status=error 
2| stats count min(_time) as firstTime max(_time) as lastTime by user host method msg 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `splunk_es_dos_investigations_manager_via_investigation_creation_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
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
splunk_es_dos_investigations_manager_via_investigation_creation_filter search *
splunk_es_dos_investigations_manager_via_investigation_creation_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
T1499 Endpoint Denial of Service Impact
KillChainPhase.ACTIONS_ON_OBJECTIVES
NistCategory.DE_CM
Cis18Value.CIS_10
Sandworm Team

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

This search requires access to internal indexes. Only affects Splunk Enterprise Security versions lower than 7.1.2.

Known False Positives

The vulnerability requires an authenticated session and access to create an Investigation. It only affects the availability of the Investigations manager, but without the manager, the Investigations functionality becomes unusable for most users. This search gives the exact offending event.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Denial of Service Attack against Splunk ES Investigation Manager by $user$ 100 100 100
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 /opt/splunk/var/log/splunk/investigation_handler.log investigation_rest_handler
Integration ✅ Passing Dataset /opt/splunk/var/log/splunk/investigation_handler.log investigation_rest_handler

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