CVE-2024-7464: Totolink CP900 Firmware RCE Vulnerability

CVE-2024-7464 Overview

CVE-2024-7464 is a command injection vulnerability in the TOTOLINK CP900 router running firmware version 6.3c.566. The flaw resides in the setTelnetCfg function of the Telnet Service component. Attackers manipulate the telnet_enabled argument to inject arbitrary operating system commands. The vulnerability is exploitable remotely over the network and requires low-level privileges. Public disclosure of the exploit details occurred through VulDB entry 273557 and a GitHub proof-of-concept repository. TOTOLINK was contacted prior to disclosure but did not respond, leaving affected devices without a vendor-supplied patch.

Critical Impact

Remote attackers with low-privileged access can inject arbitrary commands into the TOTOLINK CP900 router, potentially gaining full control of the device and pivoting into connected networks.

Affected Products

• TOTOLINK CP900 hardware device
• TOTOLINK CP900 firmware version 6.3c.566
• Telnet Service component (setTelnetCfg function)

Discovery Timeline

• 2024-08-05 - CVE-2024-7464 published to NVD
• 2024-08-15 - Last updated in NVD database

Technical Details for CVE-2024-7464

Vulnerability Analysis

The vulnerability is classified under CWE-77, Improper Neutralization of Special Elements used in a Command. The setTelnetCfg function in the Telnet Service of the TOTOLINK CP900 router fails to sanitize the telnet_enabled parameter before passing it to a system shell. Attackers supply shell metacharacters within the parameter to break out of the intended argument context. The injected commands execute with the privileges of the service handling the request, typically root on embedded router firmware. The EPSS score of 38.368% places this vulnerability in the 97th percentile for likelihood of exploitation, reflecting its public exploit availability and trivial weaponization.

Root Cause

The root cause is missing input validation and command construction using string concatenation. The firmware accepts user-supplied data through the device management interface and incorporates it directly into a shell command. No allowlisting, escaping, or parameterized execution prevents shell interpretation of injected characters such as ;, &&, or backticks.

Attack Vector

The attack requires network reachability to the router management interface and low-privileged authenticated access. An attacker sends a crafted request to the setTelnetCfg endpoint, embedding shell commands within the telnet_enabled parameter value. The router executes the injected payload, granting the attacker arbitrary command execution. The vulnerability mechanism is documented in the GitHub Vulnerability Configuration Guide and VulDB entry 273557.

Detection Methods for CVE-2024-7464

Indicators of Compromise

• Unexpected outbound connections from the CP900 router to external hosts following management interface requests.
• HTTP requests to the router containing shell metacharacters (;, |, &, backticks) in the telnet_enabled parameter.
• Unauthorized enabling of the Telnet service on the router, indicated by listening port 23/tcp.
• New or unexpected processes spawned by the Telnet configuration handler.

Detection Strategies

• Monitor router management interface logs for POST requests targeting setTelnetCfg with anomalous parameter values.
• Inspect network flows for Telnet (tcp/23) traffic originating from or terminating at CP900 devices that previously had Telnet disabled.
• Deploy network intrusion detection signatures matching shell metacharacters in HTTP requests destined for TOTOLINK management endpoints.

Monitoring Recommendations

• Capture and analyze all administrative traffic to the CP900 web interface using a network tap or SPAN port.
• Alert on configuration changes to the Telnet service on embedded network devices.
• Track authentication events to the router and correlate with subsequent configuration-changing requests.

How to Mitigate CVE-2024-7464

Immediate Actions Required

• Restrict access to the CP900 management interface to trusted administrative networks using firewall rules or network segmentation.
• Change default and weak administrative credentials to limit the low-privilege access required for exploitation.
• Disable remote management of the router from WAN-side interfaces.
• Consider replacing affected CP900 devices with supported alternatives, as the vendor has not responded to disclosure.

Patch Information

No vendor patch is available. TOTOLINK was contacted prior to public disclosure but did not respond, according to the VulDB submission. Affected operators should monitor the TOTOLINK support site for future firmware updates addressing setTelnetCfg.

Workarounds

• Block inbound access to the router web management interface from untrusted networks at the perimeter firewall.
• Place the CP900 on an isolated management VLAN with strict access control lists permitting only authorized administrator workstations.
• Disable the Telnet service entirely at the device level if the configuration interface allows it, and monitor for unauthorized re-enablement.
• Decommission the device if it is exposed to the internet and replace it with a vendor-supported product.