CVE-2024-0998 in N200RE
Summary
by MITRE • 01/29/2024
A vulnerability was found in Totolink N200RE 9.3.5u.6139_B20201216. It has been classified as critical. This affects the function setDiagnosisCfg of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument ip leads to stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The associated identifier of this vulnerability is VDB-252267. 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 • 02/21/2024
The vulnerability identified as CVE-2024-0998 represents a critical stack-based buffer overflow flaw in the Totolink N200RE router firmware version 9.3.5u.6139_B20201216. This issue resides within the setDiagnosisCfg function of the /cgi-bin/cstecgi.cgi web interface component, which serves as a critical entry point for remote administration and diagnostic functions. The vulnerability specifically manifests when processing the ip argument parameter, creating an exploitable condition that allows attackers to manipulate memory layout through crafted input data. The stack-based nature of this buffer overflow means that attacker-controlled data can overwrite adjacent memory locations including return addresses and function pointers, potentially leading to arbitrary code execution. This vulnerability is particularly dangerous because it enables remote exploitation without requiring authentication, making it accessible to any attacker with network access to the affected device. The public disclosure of this exploit (VDB-252267) indicates that threat actors have already developed working attack vectors against this specific firmware version, increasing the risk to affected users.
The technical implementation of this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, a well-documented weakness in software development that occurs when data written to a buffer on the stack exceeds the buffer's allocated size. This flaw allows an attacker to overwrite the stack frame of the executing function, potentially corrupting the program's execution flow. The attack vector is particularly concerning as it leverages the web-based management interface of the router, which typically operates on standard HTTP ports such as port 80 or HTTPS port 443. The exploitation process would involve sending a specially crafted HTTP request containing an overly long ip parameter to the vulnerable cgi-bin endpoint, causing the buffer overflow condition to trigger during parameter processing. This type of vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1210 Exploitation of Remote Services and T1059 Command and Scripting Interpreter, as it enables remote code execution through web service exploitation.
The operational impact of this vulnerability extends beyond simple device compromise to encompass complete network infrastructure takeover. Successful exploitation could allow attackers to gain root access to the router, enabling them to modify network configurations, redirect traffic through malicious proxies, establish persistent backdoors, or use the compromised device as a launch point for further attacks against internal networks. The vulnerability affects not just individual devices but entire networks that rely on the compromised router for connectivity, potentially enabling lateral movement attacks against connected systems. Given that many home and small office networks depend on consumer-grade routers for basic connectivity and security functions, this vulnerability creates a significant attack surface that threat actors can leverage to compromise network perimeters. The lack of vendor response to early disclosure attempts compounds the risk, as users have no official patches or mitigations available to protect their systems, leaving them vulnerable to active exploitation.
Organizations and individuals affected by this vulnerability should implement immediate mitigations while awaiting potential vendor patches. Network segmentation and firewall rules should be configured to restrict access to the router's web management interface from untrusted networks, while also implementing strong authentication mechanisms where possible. The most effective immediate remediation involves disabling unnecessary web services and remote management features on affected routers, particularly if they are not actively required for network administration. Users should also consider updating to the latest firmware version from Totolink, although the vendor's lack of response suggests that official patches may not be forthcoming for this specific model. Network monitoring should be enhanced to detect unusual traffic patterns or attempts to access the vulnerable cgi-bin endpoint, and regular security assessments should be conducted to identify other potentially vulnerable network devices. The vulnerability serves as a reminder of the critical importance of firmware security in network infrastructure devices and the need for proactive vulnerability management in embedded systems that often lack proper security updates or support cycles.