CVE-2024-2853: Tenda AC10U Firmware RCE Vulnerability

CVE-2024-2853 Overview

A critical OS command injection vulnerability has been identified in Tenda AC10U router firmware versions 15.03.06.48 and 15.03.06.49. This vulnerability exists in the formSetSambaConf function within the /goform/setsambacfg endpoint, where improper handling of the usbName parameter allows remote attackers to inject and execute arbitrary operating system commands. The exploit has been publicly disclosed, and the vendor was contacted but did not respond.

Critical Impact

Remote attackers can execute arbitrary commands on vulnerable Tenda AC10U routers without authentication, potentially leading to complete device compromise, network intrusion, and lateral movement across connected systems.

Affected Products

• Tenda AC10U Firmware version 15.03.06.48
• Tenda AC10U Firmware version 15.03.06.49
• Tenda AC10U Hardware version 1.0

Discovery Timeline

• 2024-03-24 - CVE-2024-2853 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-2853

Vulnerability Analysis

This vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The vulnerable formSetSambaConf function processes user-supplied input from the usbName parameter without proper sanitization or validation before passing it to system command execution routines.

In IoT devices like the Tenda AC10U router, Samba configuration endpoints often construct shell commands using user-provided parameters to configure file sharing services. When these parameters are not properly escaped or validated, an attacker can append malicious command sequences using shell metacharacters such as semicolons (;), pipes (|), or command substitution syntax ($()).

The vulnerability can be exploited remotely over the network, requires no authentication or user interaction, and provides attackers with complete control over confidentiality, integrity, and availability of the affected device.

Root Cause

The root cause of this vulnerability lies in the formSetSambaConf function's failure to sanitize the usbName parameter before incorporating it into system commands. The function likely constructs shell commands by directly concatenating user input, allowing shell metacharacters to break out of the intended command context and execute arbitrary commands with the privileges of the web server process (typically root on embedded devices).

Attack Vector

The attack can be initiated remotely over the network by sending a specially crafted HTTP request to the /goform/setsambacfg endpoint. An attacker would supply a malicious payload in the usbName parameter containing shell metacharacters followed by arbitrary commands. Since the vulnerability requires no authentication and no user interaction, any attacker with network access to the router's management interface can exploit this vulnerability.

The attacker could leverage this vulnerability to establish persistent backdoor access, modify router configurations, intercept network traffic, pivot to other network devices, or recruit the router into a botnet. For detailed technical information about the exploitation mechanism, see the GitHub IoT Vulnerability Description.

Detection Methods for CVE-2024-2853

Indicators of Compromise

• Unexpected HTTP POST requests to /goform/setsambacfg containing shell metacharacters (;, |, $(), backticks) in the usbName parameter
• Unusual outbound connections from the router to external IP addresses
• Unexpected processes running on the router, particularly shell processes spawned from the web server
• Modified system files or configuration changes not initiated by administrators
• Evidence of reverse shell connections or command-and-control traffic originating from the router

Detection Strategies

• Monitor HTTP traffic to the router's management interface for requests to /goform/setsambacfg with suspicious parameter values
• Implement network-based intrusion detection rules to identify command injection patterns in HTTP POST data
• Deploy SentinelOne Singularity to detect anomalous process execution and network behavior on protected network segments
• Review router logs for unusual administrative activity or configuration changes

Monitoring Recommendations

• Restrict access to the router's web management interface to trusted networks or IP addresses only
• Enable logging of all administrative access and configuration changes on the router
• Monitor for firmware integrity changes or unauthorized modifications to system files
• Implement network segmentation to limit the blast radius if the router is compromised

How to Mitigate CVE-2024-2853

Immediate Actions Required

• Disable remote management access to the Tenda AC10U router from untrusted networks immediately
• Place the router's management interface behind a firewall or VPN to restrict access to authorized administrators only
• Monitor for any signs of compromise on the affected device and connected network segments
• Consider replacing the vulnerable device with a router from a vendor that provides timely security updates

Patch Information

At the time of disclosure, the vendor (Tenda) was contacted but did not respond. No official patch is currently available for this vulnerability. Organizations should implement the workarounds below and monitor the VulDB entry #257777 for updates on vendor response and potential patches.

Workarounds

• Disable the Samba/USB file sharing functionality on the router if not required for business operations
• Implement strict firewall rules to block external access to the router's management interface (typically port 80/443)
• Deploy a web application firewall (WAF) or intrusion prevention system (IPS) in front of the router to filter malicious requests
• Segment the network to isolate the vulnerable router from critical systems and sensitive data
• Consider replacing the device with a supported router that receives regular security updates

# Example firewall rule to restrict management interface access (iptables)
# Allow management access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP