CVE-2023-41223 in DIR-3040
Summary
by MITRE • 05/03/2024
D-Link DIR-3040 prog.cgi SetQuickVPNSettings PSK Stack-Based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-3040 routers. Authentication is required to exploit this vulnerability.
The specific flaw exists within the prog.cgi binary, which handles HNAP requests made to the lighttpd webserver listening on TCP ports 80 and 443. The issue results from the lack of proper validation of a user-supplied string before copying it to a fixed-size stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-21623.
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Analysis
by VulDB Data Team • 05/15/2025
The CVE-2023-41223 vulnerability represents a critical stack-based buffer overflow in the D-Link DIR-3040 router's prog.cgi component, which operates as part of the lighttpd webserver infrastructure. This vulnerability resides within the SetQuickVPNSettings functionality that processes HNAP (Home Network Access Protocol) requests, making it particularly dangerous as it targets the router's web management interface. The flaw exists in the handling of user-supplied parameters during VPN configuration, creating an exploitable condition that can be leveraged by attackers with network adjacency. The vulnerability's classification as a remote code execution issue indicates that successful exploitation could allow attackers to gain complete control over the affected device, potentially compromising the entire network infrastructure.
The technical implementation of this vulnerability stems from improper input validation within the prog.cgi binary, which processes HNAP requests on TCP ports 80 and 443. Specifically, when the system receives a SetQuickVPNSettings request containing a Pre-Shared Key (PSK) parameter, it fails to properly validate the length of the user-supplied string before copying it into a fixed-size stack-based buffer. This classic buffer overflow condition occurs because the application does not enforce bounds checking on the PSK input, allowing an attacker to provide input that exceeds the allocated buffer space. The vulnerability manifests when the program attempts to copy the oversized input string into a stack buffer, causing memory corruption that can be exploited to overwrite return addresses and execute arbitrary code. This flaw directly maps to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader weakness of insufficient input validation.
The operational impact of CVE-2023-41223 extends beyond simple remote code execution, as successful exploitation grants attackers root-level privileges on the affected router. This privilege escalation capability means that attackers can modify router configurations, disable security features, redirect network traffic, or establish persistent backdoors within the network infrastructure. The vulnerability's requirement for authentication to exploit suggests that attackers must first obtain valid credentials, but this does not significantly reduce the risk as many users employ default or weak passwords. Once exploited, the compromised router can serve as a launching point for lateral movement within the network, potentially enabling attackers to access connected devices, steal sensitive data, or conduct man-in-the-middle attacks. The ZDI-CAN-21623 reference indicates this vulnerability was identified by the Zero Day Initiative and received significant attention within the cybersecurity community.
Mitigation strategies for CVE-2023-41223 should prioritize immediate firmware updates from D-Link, as the vendor has likely released patches addressing this specific vulnerability. Network administrators should implement strict access controls by disabling unnecessary services, particularly the web management interface, and restricting access to only trusted IP addresses. The implementation of network segmentation and firewall rules can help prevent unauthorized access to the router's management ports. Additionally, monitoring for unusual network traffic patterns or unauthorized configuration changes can help detect exploitation attempts. Security professionals should also consider implementing intrusion detection systems that can identify malicious HNAP requests targeting the vulnerable prog.cgi component. The vulnerability's classification as a remote code execution issue makes it particularly important to maintain up-to-date security monitoring solutions that can detect abnormal behavior patterns consistent with exploitation attempts. Organizations should also conduct regular vulnerability assessments and penetration testing to identify and remediate similar issues within their network infrastructure, as this vulnerability demonstrates the importance of proper input validation in web applications.