In this article, we’re digging deep into CVE-2022-44156, a vulnerability in the Tenda AC15 router model, firmware version V15.03.05.19. This critical bug allows attackers to cause a buffer overflow through the formSetIpMacBind function, leading to possible device takeover.

We’ll explain how it works, break down the code, and share exploit details — in clear, simple terms. By the end, you’ll know why this vulnerability matters and how to protect your network.

What is Tenda AC15 and Why Should I Care?

Tenda AC15 is a popular wireless router frequently used in small homes and offices. Like many embedded devices, it comes with a web-based management interface. Security issues in such routers can let attackers control your network, steal data, or launch attacks on other devices.

Firmware version: V15.03.05.19

- Vulnerable endpoint/function: formSetIpMacBind (HTTP POST request handler)
- CVE page: https://nvd.nist.gov/vuln/detail/CVE-2022-44156

In plain English:
An attacker can send a specially crafted POST request to your router’s web interface. If the attacker controls the local network — or remote access is enabled — this could let them run arbitrary code as root on your router. This means full device takeover.

The Vulnerable Function: formSetIpMacBind

This function is responsible for handling the “IP-MAC Binding” setting in your Tenda router’s web UI.

Here’s a simplified version of the vulnerable code (C pseudocode)

void formSetIpMacBind(request *req)
{
    char buf[256]; // Vulnerable buffer
    // Copy user input directly to buffer
    strcpy(buf, req->GetPostField("deviceName"));
    
    // ... process more fields
}

What’s the problem?
The function copies user input directly into a fixed 256-byte buffer with no length checks. If an attacker submits a deviceName longer than 256 bytes, the extra data will overflow into adjacent memory, overwriting it. With careful input, this can let the attacker control what the CPU does next.

Crafting the Payload

- Create an HTTP POST request to the router’s IP (by default, http://192.168..1 or http://192.168.1.1).

import requests

router_url = "http://192.168..1/goform/formSetIpMacBind"

'enable': '1'

}

`

This can crash the router (“denial of service”) or, if the overflow is properly crafted, execute malicious code.

Real-World Impact

- Remote Code Execution (RCE): Attackers that can access the router’s web interface (usually from the local network) can run code as root.

Persistence: Attackers may backdoor the device, making cleanup difficult.

- Denial of Service: Even a simple buffer overflow can crash your router, taking down your network.

References & Further Reading

- NVD entry for CVE-2022-44156
- CVE Details: Tenda AC15 formSetIpMacBind
- Original disclosure on GitHub (sample exploit)
- Exploit-DB: Tenda AC15 IP/MAC Binding Buffer Overflow

Update Firmware:

Check with Tenda for firmware updates that fix this vulnerability. If updates are available, install them right away.

Conclusion

CVE-2022-44156 is a serious buffer overflow vulnerability in Tenda AC15 routers. Because it’s so easy to exploit — just a long string in a web form — it poses real danger, especially if you haven’t updated your firmware. Take action now: secure your devices, keep your software current, and stay aware.

Stay safe — your Wi-Fi depends on it!

*This analysis is original content, providing a straightforward explanation of CVE-2022-44156, how it works, and why it matters. For more, follow the links in References above.*

Timeline

Published on: 11/21/2022 16:15:00 UTC
Last modified on: 11/22/2022 01:07:00 UTC