Detection: Splunk RCE via Serialized Session Payload

Description

The following analytic detects the execution of a specially crafted query using the 'collect' SPL command in Splunk Enterprise versions lower than 8.2.12, 9.0.6, and 9.1.1. It leverages audit logs to identify searches containing both 'makeresults' and 'collect' commands. This activity is significant because it can indicate an attempt to serialize untrusted data, potentially leading to arbitrary code execution. If confirmed malicious, this could allow an attacker to execute code within the Splunk environment, leading to unauthorized access and control over the system.

1`audit_searches` file=* (search="*makeresults*" AND search="*collect*") 
2| stats count min(_time) as firstTime max(_time) as lastTime by action file user splunk_server search 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `splunk_rce_via_serialized_session_payload_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
audit_searches index=_audit sourcetype=audittrail action=search
splunk_rce_via_serialized_session_payload_filter search *
splunk_rce_via_serialized_session_payload_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
T1190 Exploit Public-Facing Application Initial Access
KillChainPhase.DELIVERY
NistCategory.DE_AE
Cis18Value.CIS_10
APT28
APT29
APT39
APT41
APT5
Axiom
BackdoorDiplomacy
BlackTech
Blue Mockingbird
Cinnamon Tempest
Dragonfly
Earth Lusca
FIN13
FIN7
Fox Kitten
GALLIUM
GOLD SOUTHFIELD
HAFNIUM
Ke3chang
Kimsuky
Magic Hound
Moses Staff
MuddyWater
Rocke
Sandworm Team
Threat Group-3390
ToddyCat
Volatile Cedar
Volt Typhoon
menuPass

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

Requires access to the _audit index.

Known False Positives

There are numerous many uses of the 'makeresults' and 'collect' SPL commands. Please evaluate the results of this search for potential abuse.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Potential abuse of the 'collect' SPL command against $splunk_server$ by detected by $user$ 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 audittrail audittrail
Integration ✅ Passing Dataset audittrail audittrail

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