Detection: Splunk ES DoS Through Investigation Attachments

Updated Date: 2024-05-29 ID: bb85b25e-2d6b-4e39-bd27-50db42edcb8f Author: Rod Soto, Eric McGinnis, Chase Franklin Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects attempts to perform a denial of service (DoS) attack through investigation attachments in Splunk Enterprise Security (ES) versions below 7.1.2. It leverages internal Splunk logs, specifically monitoring the splunkd_investigation_rest_handler for error statuses related to investigation objects. This activity is significant because it can render the Investigation feature inaccessible, disrupting incident response and forensic analysis. If confirmed malicious, this attack could prevent security teams from effectively managing and investigating security incidents, leading to prolonged exposure and potential data breaches.

1`splunkd_investigation_rest_handler` status=error object=investigation 
2| stats min(_time) as firstTime max(_time) as lastTime values(status) as status values(msg) as msg values(id) as investigation_id by user 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `splunk_es_dos_through_investigation_attachments_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_through_investigation_attachments_filter search *
splunk_es_dos_through_investigation_attachments_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 Enterprise Security versions below 7.1.2.

Known False Positives

This search will show the exact DoS event via error message and investigation id. The error however does not point exactly at the uploader as any users associated with the investigation will be affected. Operator must investigate using investigation id the possible origin of the malicious upload. Attack only affects specific investigation not the investigation manager.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Denial of Service detected at Splunk ES affecting $user$ 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