CVE-2024-7158 Overview
CVE-2024-7158 is a command injection vulnerability in the TOTOLINK A3100R router firmware version 4.1.2cu.5050_B20200504. The flaw resides in the setTelnetCfg function within /cgi-bin/cstecgi.cgi, part of the HTTP POST request handler. Attackers manipulate the telnet_enabled argument to inject arbitrary operating system commands. The vulnerability is remotely exploitable and public exploit details have been disclosed. According to the referenced VulDB entry, the vendor was contacted about the issue but did not respond. The vulnerability is classified under CWE-77: Improper Neutralization of Special Elements used in a Command.
Critical Impact
Authenticated remote attackers can inject arbitrary commands into the router's HTTP handler, enabling unauthorized control of the affected device.
Affected Products
- TOTOLINK A3100R firmware version 4.1.2cu.5050_B20200504
- TOTOLINK A3100R hardware device
- Deployments exposing the /cgi-bin/cstecgi.cgi interface
Discovery Timeline
- 2024-07-28 - CVE-2024-7158 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-7158
Vulnerability Analysis
The vulnerability is a command injection flaw in the setTelnetCfg handler of the TOTOLINK A3100R CGI binary. The endpoint /cgi-bin/cstecgi.cgi accepts HTTP POST requests containing configuration parameters for the router's Telnet service. The telnet_enabled parameter is passed to a shell context without adequate neutralization of shell metacharacters. Attackers who reach the CGI endpoint can append operating system commands to the parameter value, which are then executed on the router with the privileges of the CGI process. Successful exploitation impacts confidentiality, integrity, and availability of the router.
Root Cause
The root cause is improper input sanitization in the setTelnetCfg function. User-supplied data for the telnet_enabled argument is concatenated into a system command string. Shell metacharacters such as ;, |, and ` are not filtered or escaped. This falls under [CWE-77] Command Injection.
Attack Vector
An attacker sends a crafted HTTP POST request to /cgi-bin/cstecgi.cgi targeting the setTelnetCfg topic and supplies malicious content in the telnet_enabled field. The router's CGI process interprets the injected characters as command separators and executes attacker-controlled commands. Public disclosure of the exploitation path is available in the referenced GitHub Configuration Guide and the VulDB Entry #272572.
No verified proof-of-concept code is reproduced here. Refer to the external references for the technical exploitation walkthrough.
Detection Methods for CVE-2024-7158
Indicators of Compromise
- HTTP POST requests to /cgi-bin/cstecgi.cgi referencing setTelnetCfg with shell metacharacters in the telnet_enabled parameter.
- Unexpected Telnet daemon activation on the router or unfamiliar listening ports.
- Outbound connections from the router to unknown hosts following configuration change requests.
- Modified router configuration entries related to Telnet without corresponding administrator activity.
Detection Strategies
- Inspect HTTP request bodies traversing the router's management interface for suspicious characters (;, &&, |, backticks) inside CGI parameters.
- Correlate management-plane access logs with source IPs outside the expected administrative range.
- Alert on any Telnet configuration change events on IoT/SOHO devices monitored by the SOC.
Monitoring Recommendations
- Log and forward router administrative access to a central SIEM or data lake for query and retention.
- Baseline expected management traffic patterns and alert on deviations from known administrator sources.
- Monitor firmware and device inventory to identify unpatched TOTOLINK A3100R units in the environment.
How to Mitigate CVE-2024-7158
Immediate Actions Required
- Restrict access to the router's web management interface to trusted management VLANs only.
- Disable remote WAN-side administration on TOTOLINK A3100R devices immediately.
- Rotate administrator credentials and audit device configuration for unauthorized changes.
- Segment affected IoT devices from sensitive corporate assets to limit lateral movement.
Patch Information
As of the referenced disclosure, the vendor did not respond to reporter contact and no official patched firmware has been published in the enriched data. Review the VulDB CTI Alert #272572 and TOTOLINK's official channels for firmware updates. Replace end-of-life devices where updates are not available.
Workarounds
- Block external access to /cgi-bin/cstecgi.cgi at an upstream firewall or reverse proxy.
- Disable the Telnet service on the router and enforce SSH-based management where possible.
- Place the device behind a network access control layer that terminates untrusted management traffic.
# Example ACL to restrict router management interface
# Replace 10.10.0.0/24 with your management network
iptables -A FORWARD -d <router-ip> -p tcp --dport 80 -s 10.10.0.0/24 -j ACCEPT
iptables -A FORWARD -d <router-ip> -p tcp --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
