CVE-2024-3909 in AC500
Summary
by MITRE • 04/17/2024
A vulnerability classified as critical was found in Tenda AC500 2.0.1.9(1307). Affected by this vulnerability is the function formexeCommand of the file /goform/execCommand. The manipulation of the argument cmdinput leads to stack-based buffer overflow. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The identifier VDB-261145 was assigned to this vulnerability. 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 • 02/07/2025
This critical vulnerability exists in Tenda AC500 router firmware version 2.0.1.9(1307) and affects the web-based management interface through the /goform/execCommand endpoint. The vulnerability stems from improper input validation within the formexeCommand function where the cmdinput parameter is directly processed without adequate bounds checking. This flaw creates a stack-based buffer overflow condition that occurs when user-supplied input exceeds the allocated buffer space, potentially allowing arbitrary code execution on the affected device. The vulnerability is particularly concerning as it can be exploited remotely through network-based attacks, eliminating the need for physical access to the device.
The technical implementation of this vulnerability involves the manipulation of the cmdinput argument which is passed to the execCommand function. When an attacker sends a specially crafted payload containing excessive input data, the function fails to validate the input length against the allocated buffer size, leading to memory corruption. This type of stack-based buffer overflow represents a classic software security flaw that allows attackers to overwrite adjacent memory locations including return addresses and function pointers, potentially enabling privilege escalation and complete system compromise. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is classified as a high-risk weakness in the Common Weakness Enumeration catalog.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise of affected Tenda AC500 devices. An attacker could leverage this vulnerability to gain unauthorized access to the router's operating system, modify network configurations, redirect traffic, or establish persistent backdoors. The public disclosure of the exploit increases the risk profile significantly as malicious actors can readily implement the attack without requiring advanced technical skills. Given that the vendor did not respond to initial disclosure attempts, there is no official patch or mitigation available, leaving affected devices vulnerable to exploitation. This scenario represents a critical gap in the security update process where vendors fail to address known vulnerabilities in a timely manner, potentially leaving thousands of devices exposed to attack.
Mitigation strategies for this vulnerability should focus on immediate network segmentation and access controls to limit exposure. Organizations should implement network monitoring to detect suspicious traffic patterns that may indicate exploitation attempts, particularly targeting the /goform/execCommand endpoint. The most effective long-term solution requires the vendor to release a firmware update with proper input validation and bounds checking mechanisms. Security professionals should also consider disabling unnecessary web management interfaces and implementing network access control lists to restrict access to the affected device's management ports. This vulnerability demonstrates the importance of maintaining current firmware versions and the risks associated with vendor inaction in security disclosure processes, aligning with ATT&CK technique T1210 Exploitation of Remote Services and T1068 Local Persistence mechanisms. The public availability of the exploit creates a significant risk for any organization using unpatched Tenda AC500 devices in their network infrastructure, potentially compromising the entire network through lateral movement once initial access is achieved.