Detection: Web Spring Cloud Function FunctionRouter

Updated Date: 2024-11-15 ID: 89dddbad-369a-4f8a-ace2-2439218735bc Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies HTTP POST requests to the Spring Cloud Function endpoint containing "functionRouter" in the URL. It leverages the Web data model to detect these requests based on specific fields such as http_method, url, and http_user_agent. This activity is significant because it targets CVE-2022-22963, a known vulnerability in Spring Cloud Function, which has multiple proof-of-concept exploits available. If confirmed malicious, this activity could allow attackers to execute arbitrary code, potentially leading to unauthorized access, data exfiltration, or further compromise of the affected system.

1
2| tstats count from datamodel=Web where Web.http_method IN ("POST") Web.url="*/functionRouter*" by Web.http_user_agent Web.http_method, Web.url,Web.url_length Web.src, Web.dest Web.status sourcetype 
3| `drop_dm_object_name("Web")` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `web_spring_cloud_function_functionrouter_filter`

Data Source

Name Platform Sourcetype Source
Splunk Stream HTTP Splunk icon Splunk 'stream:http' 'stream:http'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
web_spring_cloud_function_functionrouter_filter search *
web_spring_cloud_function_functionrouter_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
T1133 External Remote Services Initial Access
Delivery
Installation
DE.CM
CIS 13

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

To successfully implement this search you need to be ingesting information on Web traffic that include fields relavent for traffic into the Web datamodel.

Known False Positives

False positives may be present with legitimate applications. Attempt to filter by dest IP or use Asset groups to restrict to servers.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

A suspicious URL has been requested against $dest$ by $src$, related to a vulnerability in Spring Cloud.

Risk Object Risk Object Type Risk Score Threat Objects
dest system 42 src

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset stream:http stream:http
Integration ✅ Passing Dataset stream:http stream:http

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: 4