CVE-2023-41222 in DIR-3040
Summary
by MITRE • 05/03/2024
D-Link DIR-3040 prog.cgi SetWan2Settings 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-21622.
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Analysis
by VulDB Data Team • 05/15/2025
The CVE-2023-41222 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 flaw resides within the handling of HNAP (Home Network Access Protocol) requests, making it particularly dangerous as it exposes the vulnerability through the router's standard web interface. The vulnerability affects TCP ports 80 and 443, which are commonly used for HTTP and HTTPS services, respectively, providing attackers with multiple potential attack vectors. The issue stems from insufficient input validation within the prog.cgi binary, which processes administrative requests from remote clients. This particular vulnerability requires authentication to exploit, meaning that an attacker must first obtain valid credentials before attempting to leverage the buffer overflow. However, the requirement for authentication does not significantly reduce the risk level since many users employ default credentials or weak passwords, making initial access relatively straightforward.
The technical exploitation of this vulnerability occurs through a classic stack-based buffer overflow mechanism where user-supplied data is copied into a fixed-size stack buffer without adequate bounds checking. This flaw falls under CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient boundary checking allows attackers to overwrite adjacent memory locations. When the prog.cgi binary processes the SetWan2Settings request, it fails to validate the length of user-provided input parameters before copying them to a stack buffer. The buffer overflow creates an opportunity for attackers to overwrite return addresses and control the instruction pointer, effectively allowing arbitrary code execution. The vulnerability is particularly severe because it enables remote code execution with root privileges, as the affected binary operates with elevated permissions. The exploitation chain typically involves crafting malicious HTTP requests containing oversized input data that triggers the buffer overflow, potentially leading to complete system compromise and persistent backdoor access.
The operational impact of CVE-2023-41222 extends far beyond simple remote code execution, as it fundamentally undermines the security posture of affected D-Link DIR-3040 installations. Network-adjacent attackers who can reach the router through the web interface can leverage this vulnerability to gain complete administrative control over the device, enabling them to modify network configurations, intercept traffic, establish persistent access points, or use the compromised router as a launching platform for further attacks within the local network. The vulnerability's presence in the HNAP protocol processing layer means that it affects the router's core administrative functionality, potentially allowing attackers to manipulate WAN settings, modify firewall rules, or disable security features. This type of vulnerability aligns with ATT&CK technique T1059.007, which covers command and script execution through web shells or similar mechanisms, and T1078.004, which addresses legitimate accounts used for persistence. The root-level execution capability creates a significant threat surface, as attackers can manipulate system files, modify system binaries, or establish persistent backdoors that survive reboots. Organizations relying on these routers for network security are particularly vulnerable, as the compromised device can serve as a pivot point for lateral movement within the network infrastructure.
Mitigation strategies for CVE-2023-41222 should prioritize immediate firmware updates from D-Link, as this represents the most effective solution to address the underlying vulnerability. Organizations should also implement network segmentation to limit access to the affected routers, ensuring that only authorized personnel can reach the administrative interfaces through secure channels. Network administrators should consider disabling unnecessary services and ports, particularly when the router is not actively being configured. Access control measures should include enforcing strong authentication practices, including the use of complex passwords and multi-factor authentication where possible. Regular security audits and network monitoring should be implemented to detect anomalous traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices and input validation, which aligns with industry standards such as OWASP Top 10 A03:2021 - Injection and the CERT/CC Secure Coding Standards. Organizations should also implement network intrusion detection systems that can identify malformed HNAP requests or unusual patterns in web traffic that might indicate exploitation attempts. Additionally, regular vulnerability assessments should be conducted to identify similar issues in other network infrastructure devices, as this type of buffer overflow vulnerability is common in embedded systems and web applications. The exploitation of this vulnerability highlights the critical need for continuous security monitoring and rapid response capabilities to address emerging threats in network infrastructure devices.