CVE-2024-7740: Ltcms SSRF Vulnerability in API Endpoint

CVE-2024-7740 Overview

A critical Server-Side Request Forgery (SSRF) vulnerability has been identified in wanglongcn ltcms version 1.0.20. This vulnerability exists in the download function within the /api/test/download API endpoint. By manipulating the url parameter, attackers can exploit the SSRF vulnerability to make unauthorized requests from the server, potentially accessing internal resources, sensitive data, or pivoting to other internal systems.

Critical Impact

Remote attackers can exploit this SSRF vulnerability to bypass access controls, access internal network resources, and potentially exfiltrate sensitive data without authentication.

Affected Products

• ltcms version 1.0.20
• ltcms API Endpoint /api/test/download
• wanglongcn ltcms Content Management System

Discovery Timeline

• 2024-08-13 - CVE-2024-7740 published to NVD
• 2024-08-21 - Last updated in NVD database

Technical Details for CVE-2024-7740

Vulnerability Analysis

This SSRF vulnerability (CWE-918) occurs in the ltcms content management system's API endpoint responsible for file downloads. The download function at /api/test/download accepts a user-controlled url parameter without proper validation or sanitization. This allows attackers to craft malicious requests that force the server to make HTTP requests to arbitrary destinations.

The vulnerability is network-accessible and requires no authentication, making it particularly dangerous in exposed deployments. An attacker can leverage this flaw to probe internal network infrastructure, access cloud metadata services (such as AWS EC2 instance metadata at 169.254.169.254), or interact with internal services that would otherwise be inaccessible from the external network.

The exploit has been disclosed publicly, increasing the risk of exploitation in the wild. The vendor was contacted regarding this disclosure but did not respond.

Root Cause

The root cause of this vulnerability is improper input validation of the url parameter in the download function. The application fails to:

1. Validate that the provided URL points to an allowed external resource
2. Implement a whitelist of permitted domains or IP ranges
3. Block requests to internal network addresses (RFC 1918 addresses, localhost, link-local addresses)
4. Sanitize or validate the URL scheme (allowing file://, gopher://, or other dangerous protocols)

Attack Vector

The attack can be initiated remotely via the network by sending crafted HTTP requests to the vulnerable API endpoint. The attacker manipulates the url parameter to target internal resources or services. This vulnerability requires no user interaction and can be exploited without prior authentication.

A typical attack scenario involves sending a request to the /api/test/download endpoint with the url parameter set to an internal IP address or cloud metadata endpoint. The server processes this request and returns the content from the internal resource to the attacker.

For detailed technical information about this vulnerability, refer to the VulDB CVE-274360 Analysis or the GitHub disclosure.

Detection Methods for CVE-2024-7740

Indicators of Compromise

• Unusual outbound HTTP requests from the ltcms server to internal IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x)
• Requests to cloud metadata endpoints such as 169.254.169.254 originating from the web application
• Access logs showing requests to /api/test/download with suspicious URL parameters targeting internal resources
• Network traffic anomalies showing the server initiating connections to unexpected internal services

Detection Strategies

• Monitor web application logs for requests to /api/test/download containing internal IP addresses, localhost references, or cloud metadata URLs
• Implement web application firewall (WAF) rules to detect and block SSRF patterns in the url parameter
• Deploy network monitoring to detect unusual outbound connections from the ltcms server to internal network segments
• Configure intrusion detection systems to alert on SSRF attack signatures targeting API endpoints

Monitoring Recommendations

• Enable detailed logging for all API endpoint access, particularly the /api/test/download endpoint
• Set up alerts for requests containing RFC 1918 addresses, link-local addresses, or cloud metadata service IPs in URL parameters
• Monitor for DNS resolution requests from the web server to internal hostnames
• Implement network segmentation monitoring to detect lateral movement attempts

How to Mitigate CVE-2024-7740

Immediate Actions Required

• Restrict access to the /api/test/download endpoint through firewall rules or application-level access controls
• Implement input validation to whitelist only allowed external domains and block internal IP ranges
• Deploy a web application firewall with SSRF protection rules
• Review and audit all API endpoints for similar URL parameter handling vulnerabilities
• Consider disabling the download functionality until a vendor patch is available

Patch Information

No official patch is currently available from the vendor. The vendor was contacted regarding this vulnerability but did not respond. Organizations using ltcms 1.0.20 should implement the workarounds described below and monitor for any future security updates from the project.

For additional details, consult the VulDB entry or the VulDB submission.

Workarounds

• Block access to the /api/test/download endpoint at the web server or reverse proxy level if the functionality is not required
• Implement a server-side whitelist of allowed download domains and reject all requests to non-whitelisted URLs
• Configure network egress filtering to prevent the server from making requests to internal IP ranges
• Use a proxy server for all outbound HTTP requests with strict URL validation and logging
• Deploy application-level controls to validate URL schemes, blocking dangerous protocols like file:// and gopher://

# Example nginx configuration to block the vulnerable endpoint
location /api/test/download {
    deny all;
    return 403;
}

# Alternative: Restrict access to specific trusted IPs only
location /api/test/download {
    allow 10.0.0.0/8;
    deny all;
}