CVE-2024-7462: Totolink N350rt Buffer Overflow Vulnerability

CVE-2024-7462 Overview

CVE-2024-7462 is a buffer overflow vulnerability in the TOTOLINK N350RT router running firmware version 9.3.5u.6139_B20201216. The flaw resides in the setWizardCfg function within /cgi-bin/cstecgi.cgi. Attackers can trigger the overflow by manipulating the ssid argument, leading to memory corruption on the device. The vulnerability is exploitable remotely over the network and a proof-of-concept exploit has been publicly disclosed. The vendor was contacted prior to disclosure but did not respond, leaving affected devices without an official patch. The issue is tracked as VDB-273555 and classified under [CWE-120].

Critical Impact

Remote attackers can corrupt memory on affected TOTOLINK N350RT routers through a malformed ssid parameter, enabling potential code execution or denial of service against perimeter network devices.

Affected Products

• TOTOLINK N350RT firmware version 9.3.5u.6139_B20201216
• TOTOLINK N350RT hardware device
• /cgi-bin/cstecgi.cgi web interface component

Discovery Timeline

• 2024-08-05 - CVE-2024-7462 published to NVD
• 2024-08-15 - Last updated in NVD database

Technical Details for CVE-2024-7462

Vulnerability Analysis

The vulnerability exists in the setWizardCfg handler of the cstecgi.cgi binary, which processes initial wizard configuration requests on the TOTOLINK N350RT router. When the handler receives the ssid parameter, it copies the supplied value into a fixed-size stack or heap buffer without enforcing length validation. Supplying an oversized ssid string overflows the destination buffer and corrupts adjacent memory regions.

The vulnerability falls under [CWE-120] — Buffer Copy without Checking Size of Input. On embedded MIPS or ARM router platforms like the N350RT, such overflows can overwrite saved return addresses or function pointers, enabling arbitrary code execution in the context of the web server process, which typically runs as root.

Root Cause

The root cause is the absence of bounds checking when copying user-supplied ssid data into a fixed-length buffer inside setWizardCfg. The CGI handler trusts the length of the incoming HTTP parameter and uses an unsafe string copy operation. No input sanitization or maximum length enforcement is applied before the copy occurs.

Attack Vector

An authenticated attacker on the network sends a crafted HTTP POST request to /cgi-bin/cstecgi.cgi invoking the setWizardCfg function with an overly long ssid value. Because the router exposes the management interface over the LAN — and in some deployments the WAN — the attack can be launched remotely without local access. The publicly disclosed proof-of-concept demonstrates triggering the overflow with a long string payload. Successful exploitation can crash the device, hijack control flow, or allow persistence on the router. Technical exploitation details are documented in the GitHub PoC Documentation.

Detection Methods for CVE-2024-7462

Indicators of Compromise

• HTTP POST requests to /cgi-bin/cstecgi.cgi containing the setWizardCfg function name and unusually long ssid parameter values
• Unexpected reboots, crashes, or service restarts of the router web management daemon
• Outbound connections from the router to unknown hosts following configuration wizard requests

Detection Strategies

• Inspect HTTP traffic destined for router management interfaces and alert on ssid parameter lengths that exceed reasonable values (greater than 32 bytes per IEEE 802.11)
• Monitor for repeated requests targeting cstecgi.cgi with wizard-related function arguments from non-administrative source addresses
• Correlate router log anomalies with network-side detections to identify post-exploitation activity

Monitoring Recommendations

• Forward router syslog and management interface access logs to a centralized analytics platform for retention and anomaly correlation
• Track network behavior of IoT and edge devices for deviations from baseline traffic patterns
• Audit firmware versions across the fleet and flag devices still running 9.3.5u.6139_B20201216

How to Mitigate CVE-2024-7462

Immediate Actions Required

• Restrict access to the router web management interface to trusted management VLANs and disable remote WAN administration
• Place affected N350RT devices behind a network segmentation boundary and block untrusted hosts from reaching /cgi-bin/cstecgi.cgi
• Rotate administrative credentials on the router to limit the value of any cached or leaked authentication material
• Inventory all TOTOLINK N350RT devices and prioritize replacement if the vendor does not release a patch

Patch Information

No vendor patch is available at the time of disclosure. According to the CVE record, the vendor was contacted prior to public disclosure but did not respond. Administrators should monitor the VulDB entry #273555 for updates and consider replacing affected hardware with supported alternatives.

Workarounds

• Disable the setup wizard and any unused web management features on the device where configuration permits
• Enforce strict firewall rules that permit management access only from a dedicated administration subnet
• Deploy an inline web application firewall or intrusion prevention system rule that drops requests to cstecgi.cgi containing ssid parameters longer than 32 bytes
• Retire end-of-support or unresponsive-vendor devices from production environments where feasible

# Example iptables rule restricting access to the router management interface
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP