CVE-2022-25075: Totolink A3000RU Firmware RCE Vulnerability

CVE-2022-25075 Overview

CVE-2022-25075 is a command injection vulnerability affecting TOTOLink A3000RU routers running firmware version V5.9c.2280_B20180512. The vulnerability exists in the "Main" function and allows remote attackers to execute arbitrary commands on the affected device via the QUERY_STRING parameter. This flaw enables unauthenticated attackers to gain complete control over vulnerable network devices.

Critical Impact

This command injection vulnerability allows unauthenticated remote attackers to execute arbitrary system commands with full privileges on affected TOTOLink routers, potentially leading to complete device compromise, network infiltration, and persistent backdoor access.

Affected Products

• TOTOLink A3000RU Firmware V5.9c.2280_B20180512
• TOTOLink A3000RU Hardware (all versions when running vulnerable firmware)

Discovery Timeline

• 2022-02-24 - CVE-2022-25075 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-25075

Vulnerability Analysis

This command injection vulnerability (CWE-78) resides in the Main function of the TOTOLink A3000RU router firmware. The vulnerability stems from improper handling of user-supplied input through the QUERY_STRING parameter. When the router processes HTTP requests, the contents of the query string are passed to system commands without adequate sanitization or validation. This allows an attacker to craft malicious requests that inject arbitrary shell commands into the execution flow.

The attack can be performed remotely over the network without requiring any authentication or user interaction. Successful exploitation grants the attacker the ability to execute commands with the same privileges as the web server process, which typically runs with elevated permissions on embedded devices. This can lead to complete device compromise, including the ability to modify router configurations, intercept network traffic, establish persistent access, or pivot to other devices on the network.

Root Cause

The root cause of this vulnerability is improper input validation in the firmware's web interface. The Main function fails to properly sanitize the QUERY_STRING parameter before incorporating it into system command execution. This is a classic case of OS command injection (CWE-78) where untrusted user input is directly concatenated into shell commands without proper escaping or validation.

Embedded devices like routers often run lightweight web servers that process CGI requests, and developers may inadvertently pass user-controlled parameters to system functions like system(), popen(), or shell backticks without sanitization. In this case, the lack of input filtering allows metacharacters and command separators (such as ;, |, &&, or backticks) to break out of the intended command context and execute attacker-controlled code.

Attack Vector

The vulnerability is exploited through the network by sending specially crafted HTTP requests to the router's web management interface. An attacker can inject shell metacharacters and commands into the QUERY_STRING parameter, which are then executed by the underlying operating system.

A typical attack scenario involves appending command injection payloads to legitimate-looking URL requests. For example, an attacker might use semicolons or pipe characters to chain malicious commands after legitimate parameters. The injected commands execute with the privileges of the web server process, typically root on embedded Linux systems.

The attack requires network access to the router's management interface, which may be accessible from the local network or, in misconfigured deployments, from the internet. No authentication is required, making this vulnerability particularly dangerous for exposed devices.

For detailed technical information about the vulnerability mechanism, refer to the GitHub IOT Vulnerability Overview.

Detection Methods for CVE-2022-25075

Indicators of Compromise

• Unexpected outbound network connections from the router to unknown IP addresses
• Unusual processes running on the device that are not part of normal firmware operation
• Modified configuration files or unauthorized user accounts on the router
• Suspicious HTTP requests in router logs containing shell metacharacters (;, |, &&, `) in query strings

Detection Strategies

• Monitor network traffic for HTTP requests to TOTOLink router management interfaces containing suspicious patterns in query parameters
• Implement intrusion detection rules to alert on command injection patterns targeting the QUERY_STRING parameter
• Review router access logs for requests containing shell metacharacters or common command injection payloads
• Deploy network-based anomaly detection to identify unusual traffic patterns from router devices

Monitoring Recommendations

• Enable comprehensive logging on network perimeter devices to capture traffic destined for router management interfaces
• Implement network segmentation to isolate IoT and network infrastructure devices from general network traffic
• Configure SIEM alerts for command injection attack signatures targeting embedded device management interfaces
• Regularly audit router configurations and firmware versions to ensure vulnerable devices are identified

How to Mitigate CVE-2022-25075

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access from the internet if not absolutely required
• Place affected routers behind a firewall that can filter malicious requests
• Monitor for firmware updates from TOTOLink and apply patches when available

Patch Information

At the time of this advisory, users should check with TOTOLink for updated firmware that addresses this vulnerability. The affected firmware version is V5.9c.2280_B20180512. Organizations should visit TOTOLink's official support channels to determine if patched firmware is available. If no patch is available, implement the recommended workarounds and consider device replacement with a supported model.

For additional details, see the GitHub IOT Vulnerability Overview.

Workarounds

• Configure firewall rules to block external access to the router's HTTP management port (typically port 80 or 8080)
• Enable access control lists (ACLs) on the router to restrict management access to specific trusted IP addresses
• Deploy a web application firewall (WAF) in front of the management interface to filter command injection attempts
• Consider replacing the vulnerable device with a supported router that receives regular security updates