Detection: Splunk DOS Via Dump SPL Command

Updated Date: 2024-05-03 ID: fb0e6823-365f-48ed-b09e-272ac4c1dad6 Author: Rod Soto Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies a potential Denial of Service (DoS) attack exploiting the dump SPL command in vulnerable Splunk Enterprise versions. It detects this activity by searching the splunk_crash_log for segmentation fault entries, indicating a crash of the Splunk daemon. This activity is significant for a SOC because it can disrupt the availability of Splunk services, impacting monitoring and incident response capabilities. If confirmed malicious, this attack could render Splunk Enterprise unusable, severely hindering an organization's ability to detect and respond to other security threats.

1`splunk_crash_log` "*Segmentation fault*" 
2| stats count by host _time 
3| `splunk_dos_via_dump_spl_command_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
splunk_crash_log (index=_internal AND sourcetype=splunkd_crash_log)
splunk_dos_via_dump_spl_command_filter search *
splunk_dos_via_dump_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
T1499.004 Application or System Exploitation Impact
KillChainPhase.ACTIONS_ON_OBJECTIVES
NistCategory.DE_AE
Cis18Value.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

This search does not require additional ingestion of data. Requires the ability to search _internal index and monitor segmentation faults.

Known False Positives

Segmentation faults may occur due to other causes, so this search may produce false positives

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Possible denial of service attack with Victim $host$ 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/splunkd.log splunkd_crash_log
Integration ✅ Passing Dataset /opt/splunk/var/log/splunk/splunkd.log splunkd_crash_log

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