CVE-2024-33789: Linksys E5600 Firmware RCE Vulnerability

CVE-2024-33789 Overview

CVE-2024-33789 is a critical command injection vulnerability affecting the Linksys E5600 wireless router firmware version 1.1.0.26. The vulnerability exists in the /API/info form endpoint, where the ipurl parameter fails to properly sanitize user-supplied input before being passed to system shell commands. This allows remote attackers to execute arbitrary operating system commands with the privileges of the web server process, potentially leading to complete device compromise.

Critical Impact

Remote unauthenticated attackers can execute arbitrary commands on vulnerable Linksys E5600 routers, enabling full device takeover, network pivoting, and persistent backdoor installation.

Affected Products

• Linksys E5600 Firmware version 1.1.0.26
• Linksys E5600 Hardware

Discovery Timeline

• 2024-05-03 - CVE-2024-33789 published to NVD
• 2025-06-10 - Last updated in NVD database

Technical Details for CVE-2024-33789

Vulnerability Analysis

This command injection vulnerability (CWE-77) stems from improper neutralization of special elements used in a command. The Linksys E5600 router's web management interface exposes an API endpoint at /API/info that accepts user input through the ipurl parameter. When processing this parameter, the firmware fails to adequately sanitize or validate the input before incorporating it into system shell commands.

The vulnerability allows unauthenticated network-accessible attackers to inject arbitrary shell commands that execute with elevated privileges on the underlying Linux-based operating system. Successful exploitation requires no user interaction and can be performed remotely over the network, making it particularly dangerous for internet-exposed devices.

Root Cause

The root cause is insufficient input validation and sanitization in the web server component handling the /API/info endpoint. The ipurl parameter value is concatenated directly into a shell command without proper escaping or validation of special characters such as semicolons, pipes, backticks, or command substitution sequences. This allows attackers to break out of the intended command context and inject malicious commands.

Attack Vector

The attack vector is network-based, requiring an attacker to have network access to the router's web management interface. An attacker can craft a malicious HTTP request to the /API/info endpoint with a specially crafted ipurl parameter containing shell metacharacters and commands. The injected commands execute in the context of the web server process, typically running with root or elevated privileges on embedded devices.

The attack can be conducted by sending a crafted HTTP POST or GET request to the vulnerable endpoint. Command injection payloads using common shell metacharacters such as ;, |, $(...), or backticks can be used to append or chain arbitrary commands to the intended operation.

For detailed technical analysis and proof-of-concept information, refer to the GitHub PoC Repository.

Detection Methods for CVE-2024-33789

Indicators of Compromise

• Unusual outbound network connections from the router to unknown IP addresses
• Unexpected processes running on the device that are not part of normal firmware operation
• Modified configuration files or presence of unauthorized scripts in the router's filesystem
• Anomalous HTTP requests to /API/info endpoint containing shell metacharacters

Detection Strategies

• Monitor HTTP traffic to the router's management interface for requests containing shell metacharacters (;, |, $(), backticks) in the ipurl parameter
• Implement network intrusion detection rules to alert on suspicious payloads targeting /API/info endpoints
• Review router access logs for unusual request patterns or high-frequency access to API endpoints
• Deploy network monitoring to detect command-and-control traffic originating from router IP addresses

Monitoring Recommendations

• Enable logging on the Linksys E5600 if available and forward logs to a centralized SIEM
• Monitor for DNS queries or network connections that are atypical for router operation
• Implement network segmentation to isolate IoT devices and limit lateral movement potential
• Regularly audit devices on the network for firmware versions matching the vulnerable release

How to Mitigate CVE-2024-33789

Immediate Actions Required

• Check if your Linksys E5600 router is running firmware version 1.1.0.26 and prioritize remediation
• Disable remote management access to the router's web interface from untrusted networks
• Place the router behind a firewall and restrict access to the management interface to trusted IP addresses only
• Monitor the Linksys support page for firmware updates addressing this vulnerability

Patch Information

At the time of analysis, no vendor advisory or official patch information is available in the public CVE data. Users should regularly check the Linksys Support Website for firmware updates and security advisories addressing CVE-2024-33789. Contact Linksys support directly for guidance on remediation options.

Workarounds

• Disable the web management interface entirely if not required for device administration
• Restrict network access to the router's management interface using firewall rules to allow only trusted IP addresses
• Consider replacing vulnerable devices with models that receive regular security updates
• Implement network segmentation to isolate the router from critical network segments

# Example: Restrict management interface access via upstream firewall
# Block external access to router management port (typically 80/443)
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin workstation
iptables -I FORWARD -s <ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s <ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 443 -j ACCEPT