Detection: Splunk Process Injection Forwarder Bundle Downloads

Updated Date: 2024-05-23 ID: 8ea57d78-1aac-45d2-a913-0cd603fb6e9e Author: Lou Stella, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies unauthorized forwarder bundle downloads from Splunk Deployment Servers. It leverages native Splunk logs, specifically the splunkd component "PackageDownloadRestHandler," to detect instances where an unauthenticated client may have downloaded forwarder bundles. This activity is significant because it could indicate a potential security breach, allowing unauthorized access to sensitive configurations and applications. If confirmed malicious, an attacker could gain insights into the deployment server's environment, potentially leading to further exploitation or lateral movement within the network.

Search

1`splunkd` component="PackageDownloadRestHandler" 
2| stats values(app) values(serverclass) by peer, host 
3| `splunk_process_injection_forwarder_bundle_downloads_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Splunk	Splunk	`'splunkd_ui_access'`	`'splunkd_ui_access.log'`	N/A

Macros Used

Name	Value
splunkd	`index=_internal sourcetype=splunkd`
splunk_process_injection_forwarder_bundle_downloads_filter	`search *`

splunk_process_injection_forwarder_bundle_downloads_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
T1055	Process Injection	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT32

APT37

APT41

APT5

Cobalt Group

Kimsuky

PLATINUM

Silence

TA2541

Turla

Wizard Spider

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 hunting search uses native logs produced when a deployment server is within your environment. Splunk SOAR customers can find a SOAR workbook that walks an analyst through the process of running these hunting searches in the references list of this detection. In order to use this workbook, a user will need to run a curl command to post the file to their SOAR instance such as "curl -u username:password https://soar.instance.name/rest/rest/workbook_template -d @splunk_psa_0622.json". A user should then create an empty container or case, attach the workbook, and begin working through the tasks.

Known False Positives

None at this time.

Associated Analytic Story

Splunk Vulnerabilities

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
$peer$ downloaded apps from $host$	35	50	70

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`
Integration	✅ Passing	Dataset	`/opt/splunk/var/log/splunk/splunkd.log`	`splunkd`

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