Detection: CrushFTP Server Side Template Injection

Updated Date: 2024-05-16 ID: ccf6b7a3-bd39-4bc9-a949-143a8d640dbc Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

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.

Search

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

Data Source

Name	Platform	Sourcetype	Source	Supported App
CrushFTP	N/A	`'crushftp:sessionlogs'`	`'crushftp'`	N/A

Macros Used

Name	Value
crushftp	`sourcetype="crushftp:sessionlogs"`
crushftp_server_side_template_injection_filter	`search *`

crushftp_server_side_template_injection_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_13

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

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

CrushFTP Vulnerabilities

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Potential exploitation of CrushFTP Server Side Template Injection Vulnerability on $dest$ by $src_ip$.	64	80	80

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	`crushftp`	`crushftp:sessionlogs`
Integration	✅ Passing	Dataset	`crushftp`	`crushftp:sessionlogs`

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: 1