CVE-2024-41319: Totolink A6000r Firmware RCE Vulnerability

CVE-2024-41319 Overview

CVE-2024-41319 is a critical command injection vulnerability discovered in the TOTOLINK A6000R router firmware. The vulnerability exists in the webcmd function, which fails to properly sanitize the cmd parameter before passing it to system command execution functions. This allows unauthenticated remote attackers to execute arbitrary commands on the affected device with root privileges, potentially leading to complete device compromise.

Critical Impact

Remote attackers can execute arbitrary system commands without authentication, enabling full device takeover, network pivoting, credential theft, and deployment of persistent malware on affected TOTOLINK A6000R routers.

Affected Products

• TOTOLINK A6000R Firmware V1.0.1-B20201211.2000
• TOTOLINK A6000R Hardware Device

Discovery Timeline

• 2024-07-23 - CVE-2024-41319 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-41319

Vulnerability Analysis

This command injection vulnerability (CWE-77) occurs within the webcmd function of the TOTOLINK A6000R router's web management interface. The function accepts user-supplied input through the cmd parameter without adequate input validation or sanitization. When an attacker sends a crafted HTTP request containing shell metacharacters or command separators, the malicious payload is passed directly to the underlying operating system for execution.

The vulnerability is particularly severe because it requires no authentication to exploit and can be triggered remotely over the network. The affected firmware version V1.0.1-B20201211.2000 processes the cmd parameter directly in a command execution context, enabling attackers to chain arbitrary commands using standard shell operators such as semicolons, pipes, or command substitution syntax.

Root Cause

The root cause of this vulnerability is improper input validation in the webcmd function. The function accepts the cmd parameter from user input and incorporates it directly into system command execution without sanitizing shell metacharacters or implementing an allowlist of permitted commands. This lack of input sanitization allows attackers to inject additional commands that execute with the privileges of the web server process, typically root on embedded devices like routers.

Attack Vector

The attack vector is network-based and requires no user interaction or prior authentication. An attacker with network access to the router's web management interface can craft a malicious HTTP request targeting the webcmd endpoint. By including shell metacharacters and malicious commands in the cmd parameter, the attacker can execute arbitrary commands on the underlying Linux operating system.

Typical exploitation involves sending a crafted GET or POST request to the vulnerable endpoint with command injection payloads such as command chaining operators (;, &&, ||) or command substitution syntax ($(command) or backticks). For detailed technical analysis and proof-of-concept examples, refer to the GitHub Vulnerability Documentation and GitHub Gist PoC.

Detection Methods for CVE-2024-41319

Indicators of Compromise

• Unexpected HTTP requests to the webcmd endpoint with suspicious cmd parameter values containing shell metacharacters
• Unusual outbound network connections originating from the router to unknown IP addresses
• Presence of unauthorized files or scripts in router filesystem directories
• Modified router configuration or unexpected firewall rule changes
• Unexpected processes running on the router that are not part of normal firmware operation

Detection Strategies

• Monitor HTTP access logs for requests to the webcmd endpoint containing shell metacharacters such as ;, |, &&, $(), or backticks
• Deploy network intrusion detection rules to identify command injection patterns targeting TOTOLINK router management interfaces
• Implement behavioral analysis to detect anomalous network traffic patterns from router devices
• Use firmware integrity monitoring to detect unauthorized modifications to router file systems

Monitoring Recommendations

• Enable logging on the router management interface and forward logs to a centralized SIEM for analysis
• Monitor for DNS queries or network connections to known malicious infrastructure originating from the router
• Implement network segmentation to isolate IoT and router management interfaces from sensitive network segments
• Regularly audit router configurations and compare against known-good baselines

How to Mitigate CVE-2024-41319

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only using firewall rules
• Disable remote management if not required and ensure the management interface is not exposed to the internet
• Isolate affected TOTOLINK A6000R devices on a separate network segment with strict access controls
• Monitor affected devices for signs of compromise and consider replacing vulnerable devices if no patch is available

Patch Information

At the time of this writing, no official patch from TOTOLINK has been identified in the available CVE data. Users should monitor the TOTOLINK support website for firmware updates addressing this vulnerability. Given the critical severity and network-accessible attack vector, organizations should prioritize replacing affected devices with secure alternatives if patches remain unavailable.

Workarounds

• Disable the web management interface entirely if feasible and manage devices through console access only
• Implement strict network access controls to ensure only authorized administrators can reach the management interface
• Deploy a web application firewall (WAF) or reverse proxy in front of the management interface to filter malicious requests
• Consider deploying network-based intrusion prevention systems (IPS) with signatures for command injection attacks

# Example firewall rule to restrict management access (Linux iptables)
# Only allow management access from trusted admin network 192.168.1.0/24
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP