CVE-2024-2810: Tenda AC15 Buffer Overflow Vulnerability

CVE-2024-2810 Overview

A critical stack-based buffer overflow vulnerability has been identified in Tenda AC15 wireless router firmware versions 15.03.05.18 and 15.03.20_multi. The vulnerability exists within the formWifiWpsOOB function located in the /goform/WifiWpsOOB endpoint. Improper handling of the index argument allows remote attackers to trigger a stack-based buffer overflow, potentially leading to complete device compromise without authentication.

Critical Impact

This vulnerability enables remote attackers to execute arbitrary code with full system privileges on affected Tenda AC15 routers. The network-accessible attack vector combined with no authentication requirements makes this flaw particularly dangerous for exposed devices.

Affected Products

• Tenda AC15 Firmware version 15.03.05.18
• Tenda AC15 Firmware version 15.03.05.20_multi
• Tenda AC15 Hardware version 1.0

Discovery Timeline

• March 22, 2024 - CVE-2024-2810 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-2810

Vulnerability Analysis

The vulnerability resides in the formWifiWpsOOB function, which handles Wi-Fi WPS Out-of-Band configuration requests on Tenda AC15 routers. This function processes HTTP requests sent to the /goform/WifiWpsOOB endpoint and fails to properly validate the length of the index parameter before copying it to a fixed-size stack buffer.

When an attacker supplies an overly long index value, the function copies this data beyond the allocated buffer boundaries, corrupting adjacent stack memory including the return address. This classic stack-based buffer overflow (CWE-121) allows attackers to hijack program execution flow and potentially gain complete control over the device.

The vulnerability is particularly severe as it requires no authentication and can be triggered by sending a crafted HTTP request directly to the router's web management interface. Successful exploitation could enable an attacker to install persistent backdoors, intercept network traffic, or pivot to attack other devices on the local network.

Root Cause

The root cause is insufficient input validation in the formWifiWpsOOB function. The function accepts user-controlled input via the index parameter without properly checking its length against the destination buffer size. The use of unsafe string handling functions that do not perform bounds checking allows data to be written past the end of the stack-allocated buffer, resulting in a classic stack-based buffer overflow condition.

Attack Vector

The attack is initiated remotely over the network through the router's HTTP-based management interface. An attacker sends a specially crafted HTTP POST request to /goform/WifiWpsOOB containing an oversized index parameter value. The malicious payload overwrites the stack, including the saved return address, allowing the attacker to redirect execution to shellcode embedded within the request or to existing code gadgets within the firmware (return-oriented programming). No user interaction or authentication is required, making this vulnerability trivially exploitable once the device is accessible.

The vulnerability is documented in the GitHub IoT Vulnerability Documentation, which provides additional technical details on the exploitation mechanism. The exploit has been publicly disclosed.

Detection Methods for CVE-2024-2810

Indicators of Compromise

• Unusual HTTP POST requests to /goform/WifiWpsOOB with abnormally long index parameter values
• Unexpected router reboots or crashes that may indicate exploitation attempts
• Modified firmware configurations or unauthorized admin account creation
• Anomalous outbound network connections from the router to unknown external hosts
• Presence of unfamiliar processes or unexpected listening ports on the router

Detection Strategies

• Implement network intrusion detection rules to monitor for HTTP requests to /goform/WifiWpsOOB with excessive parameter lengths
• Deploy deep packet inspection on traffic destined for router management interfaces
• Configure logging on upstream firewalls to capture and analyze requests targeting Tenda device management endpoints
• Use web application firewall rules to block requests with oversized input fields to IoT device endpoints

Monitoring Recommendations

• Continuously monitor network traffic to and from Tenda AC15 routers for anomalous patterns
• Review router access logs regularly for signs of exploitation attempts or unauthorized access
• Set up alerts for unexpected configuration changes or firmware modifications on affected devices
• Monitor for any unusual DNS queries or command-and-control communication patterns originating from the router

How to Mitigate CVE-2024-2810

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Disable remote management features if enabled and not strictly required
• Place affected Tenda AC15 routers behind a firewall that blocks external access to management ports
• Consider replacing vulnerable devices with alternative equipment from vendors with better security response practices
• Implement network segmentation to limit the potential impact of a compromised router

Patch Information

As of the last available information, Tenda has not responded to disclosure attempts and no official security patch has been released for CVE-2024-2810. Organizations should monitor for firmware updates from Tenda and apply any patches immediately upon availability. Given the vendor's lack of response, affected users should strongly consider migrating to alternative router solutions.

For additional technical information, refer to the VulDB Security Flaw Details and VulDB Critical Analysis.

Workarounds

• Implement strict access control lists (ACLs) to limit management interface access to specific trusted IP addresses
• Deploy a separate firewall or security appliance in front of the router to filter malicious requests
• Disable WPS functionality entirely if not required for network operations
• Monitor for and block HTTP requests to /goform/WifiWpsOOB at the network perimeter
• Consider deploying a VPN solution to access management interfaces rather than exposing them directly

# Firewall rule example to block external access to Tenda management interface
# Apply on upstream firewall or router

# iptables example - block external access to web management port
iptables -A INPUT -i eth0 -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -i eth0 -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP

# Block specific vulnerable endpoint if inline filtering is possible
# (Implementation varies by firewall vendor)