CVE-2024-9644: Four-Faith F3x36 Auth Bypass Vulnerability

CVE-2024-9644 Overview

CVE-2024-9644 is an authentication bypass vulnerability affecting the Four-Faith F3x36 router running firmware version 2.0.0. The vulnerability exists in the administrative web server where authentication is not properly enforced on certain administrative functionality. By using the bapply.cgi endpoint instead of the standard apply.cgi endpoint, a remote unauthenticated attacker can bypass authentication controls and access privileged administrative functions.

Critical Impact

Remote unauthenticated attackers can modify router settings or chain this vulnerability with other authenticated vulnerabilities to achieve complete device compromise.

Affected Products

• Four-Faith F3x36 Firmware version 2.0.0
• Four-Faith F3x36 Hardware Device

Discovery Timeline

• 2025-02-04 - CVE-2024-9644 published to NVD
• 2025-09-19 - Last updated in NVD database

Technical Details for CVE-2024-9644

Vulnerability Analysis

This authentication bypass vulnerability (CWE-306: Missing Authentication for Critical Function) allows remote attackers to interact with administrative functions on the Four-Faith F3x36 router without providing valid credentials. The core issue lies in the inconsistent enforcement of authentication across different CGI endpoints within the router's administrative web interface.

The router's web server implements authentication checks on the standard apply.cgi endpoint used for configuration changes. However, an alternative endpoint bapply.cgi provides similar functionality but lacks the same authentication enforcement, creating a pathway for unauthorized access.

Root Cause

The root cause of this vulnerability is the failure to implement consistent authentication checks across all administrative endpoints in the web server. The bapply.cgi endpoint was likely created as an alternative or backup configuration interface but was not subjected to the same security controls as the primary apply.cgi endpoint. This oversight results in a hidden API that accepts unauthenticated requests for privileged operations.

Attack Vector

The attack can be conducted remotely over the network without any user interaction or prior authentication. An attacker with network access to the router's administrative interface can directly send HTTP requests to the bapply.cgi endpoint to modify router settings or configurations.

This vulnerability is particularly dangerous because it can be chained with other authenticated vulnerabilities that may exist on the device. By first exploiting this authentication bypass, an attacker effectively gains the prerequisite access needed to exploit any vulnerability that would normally require authentication, significantly expanding the attack surface.

The exploitation requires only network connectivity to the router's administrative interface, which may be exposed on local networks or, in misconfigured deployments, accessible from the internet.

Detection Methods for CVE-2024-9644

Indicators of Compromise

• Unusual HTTP requests to bapply.cgi endpoint in router access logs
• Unexpected configuration changes on Four-Faith F3x36 routers
• Web server access logs showing unauthenticated requests to administrative CGI endpoints
• Network traffic indicating direct access to router management interfaces from untrusted sources

Detection Strategies

• Monitor HTTP access logs for requests targeting /bapply.cgi endpoint
• Implement network intrusion detection rules to alert on traffic patterns consistent with exploitation attempts
• Deploy web application firewall rules to block access to the vulnerable endpoint from untrusted sources
• Conduct regular configuration audits to identify unauthorized changes to router settings

Monitoring Recommendations

• Enable comprehensive logging on Four-Faith F3x36 routers if available
• Configure SIEM alerts for anomalous administrative access patterns
• Implement network segmentation monitoring to detect lateral movement from compromised routers
• Review router configurations periodically for unexpected modifications

How to Mitigate CVE-2024-9644

Immediate Actions Required

• Restrict network access to the router's administrative interface to trusted management networks only
• Implement firewall rules to block external access to the router's web administration interface
• Monitor for any unauthorized configuration changes on affected devices
• Consider isolating affected routers from critical network segments until patches are available

Patch Information

At the time of publication, no vendor patch information is available. Organizations should consult the VulnCheck Security Advisory for the latest remediation guidance and monitor Four-Faith's official channels for firmware updates that address this vulnerability.

Workarounds

• Block access to the bapply.cgi endpoint at the network level using firewall rules or reverse proxy configurations
• Restrict administrative interface access to specific trusted IP addresses
• Place affected routers behind a VPN to limit exposure of the administrative interface
• If possible, disable the web-based administrative interface and use alternative management methods

# Example firewall rule to restrict router admin interface access (adjust IP ranges as needed)
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP