CVE-2024-3882: Tenda W30e Buffer Overflow Vulnerability

CVE-2024-3882 Overview

A critical stack-based buffer overflow vulnerability has been identified in Tenda W30E firmware version 1.0.1.25(633). The vulnerability exists in the fromRouteStatic function within the /goform/fromRouteStatic file, where improper handling of the page argument allows an attacker to trigger a stack-based buffer overflow condition. This vulnerability can be exploited remotely by authenticated attackers to potentially execute arbitrary code or cause denial of service on affected devices.

Critical Impact

Remote attackers with low-level privileges can exploit this stack-based buffer overflow to compromise device integrity, confidentiality, and availability. The vulnerability has been publicly disclosed with exploit details available.

Affected Products

• Tenda W30E Firmware version 1.0.1.25(633)
• Tenda W30E hardware devices running vulnerable firmware

Discovery Timeline

• April 16, 2024 - CVE-2024-3882 published to NVD
• January 27, 2025 - Last updated in NVD database

Technical Details for CVE-2024-3882

Vulnerability Analysis

This vulnerability is classified as a stack-based buffer overflow (CWE-121) and out-of-bounds write (CWE-787). The fromRouteStatic function in the Tenda W30E firmware fails to properly validate the length of the page argument before copying it to a fixed-size stack buffer. When an attacker supplies an overly long input value for this parameter, the function writes beyond the allocated buffer boundaries on the stack, corrupting adjacent memory regions.

The attack can be launched remotely over the network, requiring only low-level authentication to access the vulnerable endpoint. No user interaction is required for exploitation, making this a particularly dangerous vulnerability for exposed devices. Successful exploitation could allow an attacker to overwrite the return address on the stack, potentially redirecting execution flow to attacker-controlled code.

The vendor (Tenda) was contacted about this vulnerability but did not respond, leaving affected devices without an official patch. The exploit details have been publicly disclosed, increasing the risk of active exploitation in the wild.

Root Cause

The root cause of this vulnerability is insufficient input validation in the fromRouteStatic function. The function accepts user-supplied input through the page argument and copies it to a stack-allocated buffer without first checking if the input length exceeds the buffer's capacity. This classic buffer overflow pattern allows attackers to write arbitrary data past the buffer boundaries, corrupting the stack frame and potentially gaining control of program execution.

Attack Vector

The attack vector for CVE-2024-3882 is network-based, targeting the /goform/fromRouteStatic endpoint on vulnerable Tenda W30E devices. An attacker with low-level authentication can craft a malicious HTTP request containing an excessively long value for the page parameter. When processed by the vulnerable function, this triggers the buffer overflow condition.

The exploitation flow involves sending a crafted HTTP POST request to the vulnerable endpoint with a payload designed to overflow the stack buffer. By carefully constructing the overflow data, an attacker can overwrite the function's return address and redirect execution to malicious shellcode or existing code gadgets (return-oriented programming).

For detailed technical information about this vulnerability, refer to the GitHub Vulnerability Documentation and the VulDB CVE Report #260916.

Detection Methods for CVE-2024-3882

Indicators of Compromise

• Unexpected HTTP POST requests to /goform/fromRouteStatic with abnormally long page parameter values
• Device instability, crashes, or unexpected reboots following web interface access
• Anomalous network traffic patterns originating from or destined to Tenda W30E devices
• Suspicious processes or modifications on the device firmware

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests with excessively long parameter values targeting the /goform/fromRouteStatic endpoint
• Monitor HTTP request logs for POST requests to /goform/fromRouteStatic with unusual payload sizes
• Deploy intrusion detection/prevention systems (IDS/IPS) with signatures for buffer overflow attack patterns targeting IoT devices
• Use network behavior analysis to identify anomalous traffic patterns from Tenda network devices

Monitoring Recommendations

• Enable logging on network perimeter devices to capture traffic to and from Tenda W30E devices
• Implement network segmentation to isolate IoT devices from critical network resources
• Monitor for firmware integrity changes or unauthorized modifications to device configurations
• Set up alerts for repeated failed authentication attempts or unusual access patterns to device management interfaces

How to Mitigate CVE-2024-3882

Immediate Actions Required

• Restrict network access to vulnerable Tenda W30E devices, limiting management interface exposure to trusted networks only
• Implement network-level access controls (ACLs) to block external access to the device's web interface
• Place affected devices behind a firewall with strict ingress filtering
• Consider temporarily disabling remote management functionality until a patch is available
• Monitor devices for signs of compromise and prepare for potential device replacement if no patch is released

Patch Information

No official patch is currently available from Tenda. The vendor was contacted early about this disclosure but did not respond. Users are advised to implement the workarounds below and monitor for any future firmware updates from Tenda. Given the vendor's non-responsiveness, affected organizations should evaluate replacing vulnerable devices with alternatives from vendors with better security response practices.

For additional vulnerability details, see the VulDB entry and VulDB Submission #312825.

Workarounds

• Disable remote management access to the Tenda W30E device and only allow local network administration
• Implement strict firewall rules to prevent untrusted networks from accessing port 80/443 on the device
• Deploy a reverse proxy with input validation in front of the device to filter malicious requests
• Use network segmentation to isolate affected devices from critical infrastructure
• Consider replacing vulnerable devices with hardware from vendors with active security support

# Example firewall rules to restrict access to vulnerable Tenda devices
# Block external access to web management interface
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP

# Allow only trusted management subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT