Try in Splunk Security Cloud

Description

This analytic is designed to identify attempts to exploit a server-side template injection vulnerability in CrushFTP, designated as CVE-2024-4040. This severe vulnerability enables unauthenticated remote attackers to access and read files beyond the VFS Sandbox, circumvent authentication protocols, and execute arbitrary commands on the affected server. The issue impacts all versions of CrushFTP up to 10.7.1 and 11.1.0 on all supported platforms. It is highly recommended to apply patches immediately to prevent unauthorized access to the system and avoid potential data compromises. The search specifically looks for patterns in the raw log data that match the exploitation attempts, including READ or WRITE actions, and extracts relevant information such as the protocol, session ID, user, IP address, HTTP method, and the URI queried. It then evaluates these logs to confirm traces of exploitation based on the presence of specific keywords and the originating IP address, counting and sorting these events for further analysis.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-16
  • Author: Michael Haag, Splunk
  • ID: ccf6b7a3-bd39-4bc9-a949-143a8d640dbc

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1190 Exploit Public-Facing Application Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.CM
CIS20
  • CIS 13
CVE 


1
2
3
4
5
6
7
8
9
10



`crushftp` 
| rex field=_raw "\[(?<protocol>HTTPS
|HTTP):(?<session_id>[^\:]+):(?<user>[^\:]+):(?<src_ip>\d+\.\d+\.\d+\.\d+)\] (?<action>READ
|WROTE): \*(?<http_method>[A-Z]+) (?<uri_query>[^\s]+) HTTP/[^\*]+\*" 
| eval message=if(match(_raw, "INCLUDE") and isnotnull(src_ip), "traces of exploitation by " . src_ip, "false") 
| search message!=false 
| rename host as dest 
| stats count by _time, dest, source, message, src_ip, http_method, uri_query, user, action 
| sort -_time
| `crushftp_server_side_template_injection_filter`

Macros

The SPL above uses the following Macros:

:information_source: crushftp_server_side_template_injection_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • dest
  • source
  • src_ip
  • http_method
  • uri_query
  • user
  • action
  • message

How To Implement

CrushFTP Session logs, from Windows or Linux, must be ingested to Splunk. Currently, there is no TA for CrushFTP, so the data must be extracted from the raw logs.

Known False Positives

False positives should be limited, however tune or filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 Potential exploitation of CrushFTP Server Side Template Injection Vulnerability on $dest$ by $src_ip$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 1