Detection: Splunk RCE via Serialized Session Payload

Updated Date: 2024-10-17 ID: d1d8fda6-874a-400f-82cf-dcbb59d8e4db Author: Chase Franklin, Rod Soto, Eric McGinnis, Splunk Type: Hunting Product: Splunk Enterprise Security

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.

Search

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
Splunk	Splunk	`'splunkd_ui_access'`	`'splunkd_ui_access.log'`

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

Agrius

Axiom

BackdoorDiplomacy

BlackTech

Blue Mockingbird

Cinnamon Tempest

Dragonfly

Earth Lusca

Ember Bear

FIN13

FIN7

Fox Kitten

GALLIUM

GOLD SOUTHFIELD

HAFNIUM

INC Ransom

Ke3chang

Kimsuky

Magic Hound

Moses Staff

MuddyWater

Play

Rocke

Sandworm Team

Threat Group-3390

ToddyCat

Volatile Cedar

Volt Typhoon

Winter Vivern

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

Splunk Vulnerabilities

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

https://www.splunk.com/en_us/product-security.html

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: 3