Remote Command Execution Python

Question

For educational purposes, I set up a server that allows remote command execution on Windows - or rather, I tried to. For some reason, the command line refuses to recognize some of the commands I send, but others work fine. For instance, sending the command echo "Hello World!!!" causes, as it should, a cmd window to pop up reading "Hello World!!!". Fine. But when I send the command shutdown /s /t 30 it gives me the improper syntax / help screen for the shutdown command. When I send the command msg * "Hello World" it tells me that 'msg' is not a recognized internal or external command, operable program, or batch file. Here is my server code:

import socket
import sys

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_address = ('', 4242)
sock.bind(server_address)

sock.listen(1)

connection, client_address = sock.accept()
print("Connection established with %s " % str(client_address))
while True:
    command = input("Enter a command: ")
    connection.send(bytes(command, 'UTF-8'))
    confirm = connection.recv(128)
    if confirm == "yes":
        print("[+] Command executed successfully.")
    else:
        print("[-] Command failed to execute!!!")

And here is my client code:

import socket
import sys
import os

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_address = ('', 42042)
sock.bind(server_address)

sock.connect(('192.168.1.5', 4242))

while True:
    command = str(sock.recv(1024))
    try:
        os.system(command[2:]) # an odd thing, the commands somehow came out prefaced with "b'". Ideas?
        sock.send(bytes("yes", 'UTF-8'))
    except:
        sock.send(bytes("no", 'UTF-8'))

So yeah, that's that. The fact that only SOME commands are getting screwed up is really confusing me. Anybody have any ideas? Also, what's up with that "b'"?

It does sound very odd. Why not print the command on the client before it executes just to get a better understanding? — dilbert, May 27 '14 at 22:20
I think `bytes(command, 'UTF-8')` might have something to do with it. — dilbert, May 27 '14 at 22:22
@dilbert Well, I do need to encode it before I send it off... I'll try the printing before executing thing and see what happens. — KnightOfNi, May 27 '14 at 22:28

score 0 · Answer 1 · edited May 23 '17 at 12:27

0

str(sock.recv(1024)) is not the way to convert a bytes object into a string, you should be using the sock.recv(1024).decode('UTF-8') method

You can look at the documentation for bytes.decode https://docs.python.org/3.4/library/stdtypes.html#bytes.decode

Or this related question Best way to convert string to bytes in Python 3?

edited May 23 '17 at 12:27

Community

1
1

answered May 27 '14 at 22:28

Nick

115
2
5

Right! I originally forgot to encode it at all, so I never thought to put in the decoding afterwards. Thanks! – KnightOfNi May 27 '14 at 22:31

Remote Command Execution Python

1 Answers1