CVE-2024-0928: Tenda AC10U Buffer Overflow Vulnerability

CVE-2024-0928 Overview

A critical stack-based buffer overflow vulnerability has been identified in Tenda AC10U firmware version 15.03.06.49_multi_TDE01. The vulnerability exists within the fromDhcpListClient function, where improper handling of the page and listN arguments allows an attacker to trigger a stack-based buffer overflow condition. This firmware vulnerability can be exploited remotely without authentication, potentially enabling complete device compromise.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to execute arbitrary code, gain unauthorized access, or cause denial of service on affected Tenda AC10U routers without any authentication requirements.

Affected Products

• Tenda AC10U Firmware version 15.03.06.49_multi_TDE01
• Tenda AC10U Hardware version 1.0
• Tendacn AC10U series routers running vulnerable firmware

Discovery Timeline

• 2024-01-26 - CVE-2024-0928 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-0928

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The affected fromDhcpListClient function fails to properly validate the length of user-supplied input through the page and listN parameters before copying data to a fixed-size stack buffer. When an attacker supplies oversized input values, the function writes beyond the allocated buffer boundaries, corrupting adjacent stack memory including saved return addresses and frame pointers.

The network-accessible nature of the vulnerable function, combined with the lack of authentication requirements, creates a severe attack surface. Successful exploitation could allow attackers to overwrite control flow data, redirect program execution, and achieve arbitrary code execution with the privileges of the affected service—typically root on embedded router devices.

Root Cause

The root cause of CVE-2024-0928 lies in insufficient bounds checking within the fromDhcpListClient function. The function accepts the page and listN parameters from network requests without validating their length against the destination buffer size. This classic memory corruption pattern occurs when functions use unsafe string or memory copy operations without explicit length restrictions, allowing attacker-controlled data to overflow the stack buffer.

Attack Vector

The vulnerability is exploitable over the network, requiring no user interaction or authentication. An attacker can craft malicious HTTP requests targeting the DHCP client list functionality of the router's web management interface. By manipulating the page or listN parameters with carefully constructed payloads, the attacker can:

1. Overflow the stack buffer in the fromDhcpListClient function
2. Overwrite the saved return address on the stack
3. Redirect execution to attacker-controlled code or existing executable memory regions
4. Achieve remote code execution with elevated privileges on the router

The exploitation details have been publicly disclosed, increasing the risk of active exploitation. Technical analysis is available through GitHub IoT Analysis and VulDB #252133.

Detection Methods for CVE-2024-0928

Indicators of Compromise

• Unusual or malformed HTTP requests targeting DHCP-related endpoints on the router's management interface
• Requests containing abnormally long page or listN parameter values
• Unexpected router behavior, crashes, or reboots that may indicate exploitation attempts
• Network traffic anomalies originating from or directed at the router management port

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for stack overflow attack patterns targeting Tenda devices
• Monitor HTTP traffic to router management interfaces for oversized parameters in DHCP-related requests
• Implement web application firewalls (WAF) to filter requests with excessively long parameter values
• Review router logs for repeated access attempts to DHCP client list functionality

Monitoring Recommendations

• Enable logging on network perimeter devices to capture traffic to router management interfaces
• Configure alerts for repeated failed access attempts or malformed requests to router endpoints
• Monitor for firmware integrity changes or unexpected configuration modifications on Tenda devices
• Establish baseline behavior for router management traffic to identify anomalous patterns

How to Mitigate CVE-2024-0928

Immediate Actions Required

• Restrict access to the router's web management interface to trusted networks or IP addresses only
• Disable remote management functionality if not strictly required
• Implement network segmentation to isolate vulnerable devices from untrusted networks
• Consider replacing the affected device with a router from a vendor with active security support

Patch Information

No official patch information is currently available from Tenda. The vendor was contacted early about this disclosure but did not respond. Users should monitor VulDB #252133 and Tenda's official channels for potential firmware updates. Given the lack of vendor response, organizations should prioritize compensating controls and consider device replacement.

Workarounds

• Disable the web management interface entirely and manage the router through alternative means if available
• Implement strict access control lists (ACLs) to limit management interface access to specific administrator IP addresses
• Deploy the router behind a firewall that can filter and inspect HTTP traffic to the management interface
• Use a VPN to access the management interface rather than exposing it directly to any network

# Network isolation configuration example (upstream firewall)
# Block external access to router management interface
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -j DROP

# Allow management access only from specific admin workstation
iptables -I FORWARD -s 192.168.1.100 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT