CVE-2024-3906 in AC500
Summary
by MITRE • 04/17/2024
A vulnerability was found in Tenda AC500 2.0.1.9(1307). It has been declared as critical. This vulnerability affects the function formQuickIndex of the file /goform/QuickIndex. The manipulation of the argument PPPOEPassword leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used. VDB-261142 is the identifier 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 • 01/22/2025
The vulnerability identified as CVE-2024-3906 represents a critical stack-based buffer overflow flaw in Tenda AC500 router firmware version 2.0.1.9(1307) which resides within the web interface functionality. This issue is particularly concerning as it affects the formQuickIndex function located in the /goform/QuickIndex endpoint, making it accessible through the device's web management interface. The vulnerability specifically manifests when processing the PPPOEPassword argument, which serves as the attack vector for the buffer overflow condition. The exploitation of this weakness allows remote attackers to potentially execute arbitrary code on the affected device, compromising the entire network infrastructure that relies on this router for connectivity.
The technical implementation of this vulnerability stems from improper input validation within the firmware's web server component that handles configuration forms. When the PPPOEPassword parameter is submitted through the QuickIndex form, the application fails to properly bounds-check the input data before copying it into a fixed-size stack buffer. This classic buffer overflow condition creates an opportunity for attackers to overwrite adjacent stack memory locations, potentially corrupting program execution flow and enabling code execution. The vulnerability's classification as stack-based indicates that the overflow occurs in the program's stack memory space, making it particularly dangerous as it can be exploited to overwrite return addresses, function pointers, or other critical execution metadata. This flaw directly corresponds to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader category of buffer overflow vulnerabilities that have been consistently identified as high-risk security issues in software development practices.
The operational impact of this vulnerability extends beyond simple network disruption, as it enables complete compromise of the affected router device. Remote exploitation allows attackers to gain unauthorized administrative access to the router's management interface, potentially enabling them to modify network configurations, establish persistent backdoors, redirect traffic, or use the device as a pivot point for attacking other systems within the local network. The fact that this vulnerability has been publicly disclosed and is known to be exploitable increases the risk significantly, as it removes the element of surprise that typically protects systems from zero-day attacks. Network administrators face the challenge of securing devices that may already be compromised, while attackers can leverage this vulnerability to conduct reconnaissance and establish persistent access to otherwise protected network segments. The vulnerability's remote exploitability eliminates the need for physical access to the device, making it particularly dangerous for enterprise and residential networks alike. According to ATT&CK framework, this vulnerability maps to T1059 Command and Scripting Interpreter and T1078 Valid Accounts, as it enables adversaries to execute commands and maintain persistent access through compromised router credentials.
The lack of vendor response to early disclosure attempts compounds the severity of this vulnerability, leaving users without official patches or security updates to address the issue. This situation creates a dangerous gap in security coverage where affected devices remain vulnerable to exploitation for extended periods. The absence of vendor communication also suggests potential delays in patch development or deployment, which could leave organizations exposed to attacks while they await security updates. Organizations should immediately implement network segmentation strategies to limit access to potentially compromised devices, monitor network traffic for signs of exploitation attempts, and consider disabling unnecessary web management interfaces until patches are available. The vulnerability's designation as critical by security vendors indicates that it should be prioritized for immediate remediation, particularly in environments where network security is paramount. The public availability of exploit code further accelerates the urgency for remediation, as attackers can readily leverage this vulnerability without requiring advanced technical skills to compromise affected systems. Network defenders should also consider implementing intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability, as the attack patterns are predictable and well-documented in security advisories.