CVE-2024-35571: Tenda AX1806 Buffer Overflow Vulnerability

CVE-2024-35571 Overview

CVE-2024-35571 is a stack overflow vulnerability affecting the Tenda AX1806 router running firmware version 1.0.0.1. The vulnerability exists in the formSetIptv function and can be triggered through the iptv.stb.mode parameter. This firmware vulnerability allows remote attackers to potentially execute arbitrary code or cause a denial of service condition on affected devices without authentication.

Critical Impact

This stack overflow vulnerability can be exploited remotely over the network without any user interaction or authentication, potentially allowing complete compromise of the affected router device.

Affected Products

• Tenda AX1806 Firmware version 1.0.0.1
• Tenda AX1806 Router Hardware

Discovery Timeline

• 2024-05-20 - CVE-2024-35571 published to NVD
• 2025-03-17 - Last updated in NVD database

Technical Details for CVE-2024-35571

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw exists in the formSetIptv function within the Tenda AX1806 firmware. When processing the iptv.stb.mode parameter, the function fails to properly validate the length of user-supplied input before copying it to a fixed-size stack buffer. This allows an attacker to supply an overly long value that exceeds the buffer's allocated size, overwriting adjacent memory on the stack including potentially critical control flow data such as return addresses and saved frame pointers.

Root Cause

The root cause of this vulnerability is improper input validation in the formSetIptv function. The function copies user-controlled data from the iptv.stb.mode parameter into a stack-allocated buffer without performing adequate bounds checking. The absence of length verification before the memory copy operation allows attackers to overflow the destination buffer and corrupt adjacent stack memory, which can lead to control flow hijacking.

Attack Vector

The attack vector for CVE-2024-35571 is network-based, meaning an attacker can exploit this vulnerability remotely by sending a specially crafted HTTP request to the router's web management interface. The attack requires no privileges or authentication, and no user interaction is needed to trigger the vulnerability. An attacker would craft a malicious request containing an excessively long value in the iptv.stb.mode parameter, targeting the formSetIptv function endpoint.

The vulnerability manifests when the formSetIptv function processes the oversized iptv.stb.mode parameter value without proper bounds checking. For detailed technical analysis of the buffer overflow condition, refer to the Notion Buffer Overflow Analysis.

Detection Methods for CVE-2024-35571

Indicators of Compromise

• Unusual HTTP requests to the router's web interface containing abnormally long iptv.stb.mode parameter values
• Router crashes or unexpected reboots that may indicate exploitation attempts
• Unexplained changes to router configuration or firmware

Detection Strategies

• Monitor network traffic for HTTP requests targeting IPTV configuration endpoints with oversized parameters
• Implement intrusion detection rules to identify buffer overflow patterns in router management traffic
• Deploy network monitoring to detect anomalous connections to router administrative interfaces

Monitoring Recommendations

• Enable logging on network perimeter devices to capture traffic to router management interfaces
• Monitor for firmware integrity changes on affected Tenda AX1806 devices
• Implement alerting for repeated failed or malformed requests to router configuration endpoints

How to Mitigate CVE-2024-35571

Immediate Actions Required

• Restrict access to the router's web management interface to trusted networks only
• Disable remote management features if not required
• Place affected routers behind a firewall that blocks untrusted access to the management interface
• Monitor for and apply any firmware updates from Tenda

Patch Information

As of the last update, no official patch information is available from Tenda for this vulnerability. Users should regularly check the Tenda support website for firmware updates that address CVE-2024-35571. Consider replacing the affected device if the vendor does not provide a timely security fix.

Workarounds

• Implement network segmentation to isolate affected routers from untrusted networks
• Configure firewall rules to block external access to the router's HTTP management ports
• Disable the IPTV configuration functionality if not in use
• Use access control lists (ACLs) to limit management access to specific trusted IP addresses

# Example firewall rule to restrict access to router management interface
# Block external access to port 80/443 on router management IP
iptables -A INPUT -p tcp -d <router_ip> --dport 80 -s ! <trusted_network> -j DROP
iptables -A INPUT -p tcp -d <router_ip> --dport 443 -s ! <trusted_network> -j DROP