Hacking a server program

This is a discussion on Hacking a server program within the Networking/Device Communication forums, part of the General Programming Boards category; Hi I have been programing a little while with python and set up a small server program that waits for ...

  1. #1
    adr
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    Hacking a server program

    Hi I have been programing a little while with python and set up a small server program that waits for name and password to be entered. If the user name or the pass would is wrong, you have to restart. Is there any way to hack the server besides just brute forcing names and passwords? If there is, mind sharing some ideas so I can stop this from happening? Also its a UDP connection.

    Here some of my code:
    Code:
    		data2 = data + ".txt"
    		f = open(data2,"r")
    		lineList = f.readlines()
    		f.close()
    		name = data
    		name2 = "Name: " + data + "\n"
    		if name2 == lineList[0]:
    				  data,addr = UDPSock.recvfrom(buf)
    				  password = "Password: " + data + "\n"
    				  if password == lineList[1]:
    						        print name,"log on."
    							data = name
    							(UDPSock.sendto(data,addr2))
    							data = "===Welcome==="
    							(UDPSock.sendto(data,addr2))
    						        while 1:
    								class receiver(threading.Thread) :  # Receiver thread
      								  def __init__(self, socket ):
          									threading.Thread.__init__(self)
          									self.setDaemon(True)  
       								  def run(self) :
          									while True :                           # Receive thread
                									data,addr = UDPSock.recvfrom(buf)
                									if not data : break
                									print data
          									UDPSock.close()
    								receiver(UDPSock).start()
    								while True :                                 # Send in main thread
       									data = time.ctime() + " Mradr: " + raw_input()
       									(UDPSock.sendto(data,addr2))
    								UDPSock.close()
    Last edited by adr; 02-17-2008 at 10:11 AM.

  2. #2
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    Is this python? (sorry I have to ask because I've never really used python)

  3. #3
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    yes! its is Python!
    now answer the OP's question

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    While some one here may know if an exploit exists in your code i foresee two problems:
    1) this is a C/C++ forum so I'm not entirely sure anyone will answer your question.
    2) #6 of the forum guidelines sticky specifically mentions things like hacking and cracking programs are frowned upon

    just my thoughts
    Last edited by MikeyIckey; 02-20-2008 at 05:05 PM.

  5. #5
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    Quote Originally Posted by MikeyIckey View Post
    2) #6 of the forum guidelines sticky specifically mentions things like hacking and cracking programs are frowned apon
    Although the original poster actually asked for ways to AVOID people breaking into the server, if there is any holes in the code, which I believe is a valid question.

    I'm not able to comment on the original question any further than the previous post has.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  6. #6
    Cat without Hat CornedBee's Avatar
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    Why two tabs of indentation per level? Isn't one enough?

    Your variable names leave a lot to be desired. data? data2? name? name2?

    Where does data come from? If it's user input, you have a possible directory traversal attack on your hands.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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    Quote Originally Posted by matsp View Post
    Although the original poster actually asked for ways to AVOID people breaking into the server, if there is any holes in the code, which I believe is a valid question.
    Oh, not to say that it might not be a valid question.
    But he might get a better answer from a python or web programming board (if it's for a web application, of coarse)

    just a quick google search, I found
    http://forums.devshed.com/python-programming-11/

    not to stop you from posting on the C boards, but in this case, you might find some one better suited to answer your specific question.
    Hope it helps

    -M.I.

  8. #8
    adr
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    Quote Originally Posted by MikeyIckey View Post
    While some one here may know if an exploit exists in your code i foresee two problems:
    1) this is a C/C++ forum so I'm not entirely sure anyone will answer your question.
    2) #6 of the forum guidelines sticky specifically mentions things like hacking and cracking programs are frowned upon

    just my thoughts
    Hi, yea your right on number #6, and I am same with the forums guidelines and I also look down upon programs that use their power to hack or crack into or otherwise steal. I am not asking how to hack or crack, or how to use the holes to my power. I am asking how to patch or cover up the holes so that other users cant come in upon and protect my server/computer from hanfull people/programs. To which I believe is a valid question too.

    Thanks for the help so far, and I know this is a c/c++ forum. I am just used to this board and getting information =) (really like the people here)

    "Where does data come from? If it's user input, you have a possible directory traversal attack on your hands."
    No, I have it in the server, code lines like down below. Would the attack still be possable?

    Thank you also MikeyIckey for the link, i'll look around inside their forum for some of my answer.

    I do have another question thats more networking then a programming. When I try to do the UDP connection the client couldn't connect. We both have routers and I wasnt sure on how to hook them up (or aka setting up port forwarding). This is what I have so far and set up the router like so.
    App: Client2, Port From: 21567, Protocol: Both, IP Address: 192.168.1.135, Port to: 21568, and enable

    (my side)
    WAN: 75.134.61.245
    LAN: 192.168.1.135

    Code:
    # Server program
    
    from socket import *
    import threading
    import time
    
    
    # Set the socket parameters
    host = "75.134.61.245"
    port = 21568
    port2 = 21567
    buf = 1024
    buf2 = 1024
    addr = (host,port)
    
    # Create socket and bind to address
    UDPSock = socket(AF_INET,SOCK_DGRAM)
    UDPSock.bind(addr)
    
    data,addr = UDPSock.recvfrom(buf)
    client = data
    addr2 = (client, port2)
    data,addr = UDPSock.recvfrom(buf)
    if data == "Hey you there?":
                                 data = "Yes"
                                 (UDPSock.sendto(data,addr2))
    			     print client, " trying to log on."
    
    # Receive messages
    while 1:
            data,addr = UDPSock.recvfrom(buf)
            if not data:
    		print "Client has exited!"
    		break
    
            else:
    		data2 = "Users/" + data + ".txt"
    		f = open(data2,"r")
    		lineList = f.readlines()
    		f.close()
    		name = data
    		name2 = "Name: " + data + "\n"
    		if name2 == lineList[0]:
    				  data,addr = UDPSock.recvfrom(buf)
    				  password = "Password: " + data + "\n"
    				  if password == lineList[1]:
    						        print name,"log on."
    							data = name
    							(UDPSock.sendto(data,addr2))
    							data = "===Welcome==="
    							(UDPSock.sendto(data,addr2))
    						        while 1:
    								class receiver(threading.Thread) :  # Receiver thread
      								  def __init__(self, socket ):
          									threading.Thread.__init__(self)
          									self.setDaemon(True)  
       								  def run(self) :
          									while True :                           # Receive thread
                									data,addr = UDPSock.recvfrom(buf)
                									if not data : break
                									print data
          									UDPSock.close()
    								receiver(UDPSock).start()
    								while True :                                 # Send in main thread
       									data = time.ctime() + " Mradr: " + raw_input()
       									(UDPSock.sendto(data,addr2))
    								UDPSock.close()
    
    				  else:
                                           			print "Wrong."
    		else:
    				print "No one by that name."  
    
    # Close socket
    UDPSock.close()
    Last edited by adr; 02-21-2008 at 10:40 PM.

  9. #9
    Cat without Hat CornedBee's Avatar
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    Code:
            data,addr = UDPSock.recvfrom(buf)
            if not data:
    		print "Client has exited!"
    		break
    
            else:
    		data2 = "Users/" + data + ".txt"
    		f = open(data2,"r")
    This part is a bit unsafe. You put what you received from the user into a path and open that path, without checking that the user's input doesn't contain, say, a '..' or a '/'. That's potentially dangerous. (The fact that you never let the user see the content mitigates the danger, but the danger is something you need to understand.)
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  10. #10
    adr
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    Quote Originally Posted by CornedBee View Post
    Code:
            data,addr = UDPSock.recvfrom(buf)
            if not data:
    		print "Client has exited!"
    		break
    
            else:
    		data2 = "Users/" + data + ".txt"
    		f = open(data2,"r")
    This part is a bit unsafe. You put what you received from the user into a path and open that path, without checking that the user's input doesn't contain, say, a '..' or a '/'. That's potentially dangerous. (The fact that you never let the user see the content mitigates the danger, but the danger is something you need to understand.)
    Thanks, ok I can work around that by checking the string befor pasting it on to the data2 buf setup.

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