Detection: Splunk Enterprise Windows Deserialization File Partition

Updated Date: 2024-07-01 ID: 947d4d2e-1b64-41fc-b32a-736ddb88ce97 Author: Rod Soto, Eric McGinnis, Chase Franklin Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies attempts to exploit a deserialization vulnerability in Splunk Enterprise for Windows versions below 9.0.8 and 9.1.3. It detects irregular path file executions by analyzing splunk_python logs and extracting file paths and names. This activity is significant because it indicates potential exploitation of a known vulnerability, which could lead to arbitrary code execution. If confirmed malicious, an attacker could gain unauthorized access, execute arbitrary code, and potentially compromise the entire Splunk environment, leading to data breaches and further system exploitation.

1`splunk_python` request_path="/*/app/search/C:\\Program" *strings* 
2| rex "request_path=(?<file_path>[^\"]+)" 
3| rex field=file_path "[^\"]+/(?<file_name>[^\"\'\s/\\\\]+)" 
4| stats min(_time) as firstTime max(_time) as lastTime values(file_path) as file_path values(file_name) as file_name by index, sourcetype, host 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `splunk_enterprise_windows_deserialization_file_partition_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_enterprise_windows_deserialization_file_partition_filter search *
splunk_enterprise_windows_deserialization_file_partition_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_CM
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 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

Requires access to internal indexes. This detection search will display irregular path file execution, which will display exploit attempts. Only applies to Microsoft Windows Splunk versions.

Known False Positives

Irregular path with files that may be purposely called for benign reasons may produce false positives.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Possible Windows Deserialization exploitation via irregular path file against $host$ 90 100 90
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 C:\Program File\Splunk\var\log\splunk\python.log splunk_python
Integration ✅ Passing Dataset C:\Program File\Splunk\var\log\splunk\python.log splunk_python

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