CVE-2024-7182: Totolink A3600r Buffer Overflow Vulnerability

CVE-2024-7182 Overview

CVE-2024-7182 is a buffer overflow vulnerability in TOTOLINK A3600R routers running firmware version 4.1.2cu.5182_B20201102. The flaw resides in the setUpgradeFW function of /cgi-bin/cstecgi.cgi, where manipulation of the FileName argument triggers a buffer overflow [CWE-120]. Attackers can exploit the issue remotely over the network with low-privileged credentials. The exploit technique has been publicly disclosed via VulDB entry VDB-272603. The vendor was contacted about this disclosure but did not respond.

Critical Impact
Remote attackers with low-level authentication can trigger a buffer overflow in the firmware upgrade handler, potentially leading to code execution or device compromise on affected TOTOLINK A3600R routers.

Affected Products

TOTOLINK A3600R router (hardware)
TOTOLINK A3600R Firmware version 4.1.2cu.5182_B20201102
CGI endpoint /cgi-bin/cstecgi.cgi (setUpgradeFW function)

Discovery Timeline

2024-07-29 - CVE-2024-7182 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-7182

Vulnerability Analysis

The vulnerability affects the setUpgradeFW function inside the /cgi-bin/cstecgi.cgi binary on TOTOLINK A3600R routers. This CGI handler processes firmware upgrade requests from the router's administrative interface. The function fails to validate the length of user-supplied input passed through the FileName parameter before copying it into a fixed-size stack or heap buffer. An attacker with valid low-privileged credentials can send a crafted HTTP request over the network to trigger memory corruption. Successful exploitation may lead to arbitrary code execution in the context of the CGI process, which typically runs with elevated privileges on embedded routers.

Root Cause

The root cause is a classic buffer overflow classified under [CWE-120]: Buffer Copy without Checking Size of Input. The setUpgradeFW handler copies the FileName argument into a bounded buffer without enforcing length checks. TOTOLINK's cstecgi.cgi binary aggregates many router configuration handlers, and this input validation gap is consistent with a broader pattern of insecure string handling seen across TOTOLINK CGI functions.

Attack Vector

Exploitation requires network access to the router's web management interface and low-privileged authentication. An attacker submits an HTTP POST request to /cgi-bin/cstecgi.cgi invoking the setUpgradeFW endpoint with an oversized FileName value. The malformed request corrupts adjacent memory and can redirect execution flow. Because embedded router management interfaces are often exposed on LAN segments and, in some cases, WAN interfaces, the attack surface extends beyond directly targeted operators to any adjacent network attacker who can reach TCP port 80/443. Public technical details are available in the GitHub Firmware Upgrade Instructions.

No verified proof-of-concept code is available in the enriched data. Refer to the VulDB #272603 entry for further technical details on the vulnerable code path.

Detection Methods for CVE-2024-7182

Indicators of Compromise

HTTP POST requests to /cgi-bin/cstecgi.cgi containing the setUpgradeFW action with an unusually long FileName parameter value.
Unexpected CGI process crashes, reboots, or watchdog-triggered restarts on TOTOLINK A3600R devices.
New or unauthorized firmware upgrade attempts originating from internal or external hosts.

Detection Strategies

Deploy network-based signatures on IDS/IPS platforms to flag cstecgi.cgi requests where the FileName parameter exceeds expected length thresholds.
Correlate router syslog data with authentication events to identify low-privileged accounts issuing firmware upgrade calls.
Monitor administrative interfaces for anomalous authenticated sessions accessing upgrade endpoints outside change windows.

Monitoring Recommendations

Forward router logs and NetFlow data to a centralized SIEM for anomaly analysis, such as SentinelOne Singularity Data Lake, which ingests network telemetry via OCSF normalization.
Establish baseline traffic profiles for router management interfaces and alert on outliers.
Track EPSS trends for CVE-2024-7182 (currently 1.091%, 62.6th percentile) to prioritize response as exploitation likelihood evolves.

How to Mitigate CVE-2024-7182

Immediate Actions Required

Restrict administrative access to the router web interface to trusted management VLANs only.
Disable remote (WAN-side) management on affected TOTOLINK A3600R devices.
Rotate all router administrative credentials and enforce strong, unique passwords to raise the bar against the low-privilege prerequisite.
Segment vulnerable A3600R devices from sensitive network zones until a fix is available.

Patch Information

No official vendor patch has been published. According to the CVE record, TOTOLINK was contacted about this disclosure but did not respond. Organizations operating the A3600R on firmware 4.1.2cu.5182_B20201102 should treat the device as unpatched and plan for replacement or compensating controls. Monitor the TOTOLINK downloads portal for future firmware releases addressing this issue.

Workarounds

Place affected routers behind an upstream firewall that filters inbound HTTP/HTTPS requests to the management interface.
Apply strict ACLs limiting access to /cgi-bin/cstecgi.cgi to a small set of trusted administrative IP addresses.
Consider replacing end-of-support or unpatched TOTOLINK A3600R units with actively maintained hardware if the vendor does not respond with a fix.
Where feasible, deploy a reverse proxy that enforces input length validation on parameters passed to CGI endpoints.

bash

# Example iptables rule limiting router management access to an admin subnet
iptables -A INPUT -p tcp --dport 80 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP