CVE-2024-4066 in AC8
Summary
by MITRE • 04/24/2024
A vulnerability classified as critical has been found in Tenda AC8 16.03.34.09. Affected is the function fromAdvSetMacMtuWan of the file /goform/AdvSetMacMtuWan. The manipulation of the argument wanMTU/wanSpeed/cloneType/mac/serviceName/serverName leads to stack-based buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-261792. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 01/22/2025
This critical vulnerability exists in the Tenda AC8 router firmware version 16.03.34.09 within the /goform/AdvSetMacMtuWan API endpoint. The flaw resides in the fromAdvSetMacMtuWan function which processes user-supplied parameters including wanMTU, wanSpeed, cloneType, mac, serviceName, and serverName. The vulnerability stems from insufficient input validation and bounds checking in the buffer handling mechanism, creating a stack-based buffer overflow condition that can be exploited through remote network access.
The technical implementation of this vulnerability allows attackers to craft malicious HTTP requests containing oversized payloads in any of the affected parameters. When the router processes these malformed inputs, the insufficient buffer size validation causes data to overflow into adjacent memory locations on the stack, potentially overwriting critical program execution data such as return addresses, function pointers, or local variables. This memory corruption creates opportunities for arbitrary code execution, privilege escalation, or denial of service conditions. The vulnerability's classification as remote exploitation capability means that attackers do not require physical access or local network presence to exploit the flaw, making it particularly dangerous for internet-facing devices.
The operational impact of this vulnerability extends beyond simple exploitation as it represents a severe security weakness that could enable complete system compromise. An attacker who successfully exploits this vulnerability could gain root access to the router's operating system, allowing them to modify network configurations, install persistent backdoors, redirect traffic through malicious servers, or use the device as a pivot point for attacking internal network resources. The fact that the exploit has been publicly disclosed and is available for use significantly increases the risk to affected users, as the attack surface is no longer limited to sophisticated threat actors but includes script kiddies and automated attack tools. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow and aligns with attack patterns described in the MITRE ATT&CK framework under T1059.007 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from Tenda if available, though the vendor's lack of response to prior disclosure creates uncertainty about official patch availability. Network segmentation and firewall rules should be implemented to restrict access to the affected API endpoint, particularly blocking external access to the router's administrative interfaces. Organizations should consider disabling unused services and implementing network monitoring to detect anomalous traffic patterns that might indicate exploitation attempts. Security teams should also conduct comprehensive vulnerability assessments of all Tenda AC8 devices within their network infrastructure, as this vulnerability affects a significant number of consumer and small office routers. The lack of vendor response underscores the importance of proactive security measures and the need for organizations to maintain awareness of publicly disclosed vulnerabilities that may affect their network infrastructure components.