Netcat fun!

This instructable shows you how to create a backdoor on a computer with netcat! I will show you two ways to do this, with and without my batch file that automates it for you. This instructable already assumes that you have already got root permissions on the computer, probably with a 0phcrack LiveCD here. Now, onto the instructable.

Step 1: Download netcat

I have saved you the trouble of 3 minutes of searching Google and have put nc.exe up on instructables for you to download. Optionally, you can also download nc.bat which is a batch file I have created to automate the process for you. Make sure that if you download nc.bat it is 464 bytes, because I kept on uploading versions and finding out something was wrong with it. If it is not 464 bytes, the program will not correspond with this instructable.

Comments

[locofocos]

Nice. I'm gonna go ahead and make an unnc.bat to undo it.

[duct tape]

cool

[locofocos]

Here's my idea. Go under your home router and enable forwarding of nc.exe on port 4444, then you could access the computer from any internet connection. I've got two computers, but my old laptop doesn't like our network, probably cause it has windows and linux on it.... If I look at all the computers on the network, it appears (when it's turned on and hooked up to the router), but not it's shared files (they are turned on to share, i'm not an idiot). If I try to see any other computers on the network from this computer, I can't see any. It's kinda like a one-way mirror. It can connect to the internet fine, but not the network. It's set up just like my desktop. Obviously, netcat won't work.

[B.F.L.M]

could you explain how to do that?

[locofocos]

Before I tell you how to do it, let me go ahead and tell you that if you do it, ANYONE who has internet (millions of people) could log into your computer and control it, so I would REALLY recommend not doing it, even to someone else's computer. With that being said, you need to forward port 4444. Your router acts as a firewall that blocks people from connecting to you that shouldn't be. If you want to communicate with the outside world, you have to tell your router you want to "forward" that port. It will only forward it from the outside world to one IP address. Go check out http://portforward.com/routers.htm to help you do that.

[duct tape]

you might want to set up some sort of login to the machine so that anonymous entry is harder. An IP logger would be another good addition.

[duct tape]

that is strange. you went to whatismyip.org or something similar to find the IP address first, right?

[locofocos]

Yeah. I'm not saying I've actually done it, but it should work.

[duct tape]

k

[paozie]

go to Start and click on run and then on cmd and type in IPconfig/all and then find your IP address. :D

[duct tape]

that only shows your network ip. to access it from the 'net you need the other one.

[jund4]

Hi can anyone tell how to use netcat on internet cuz i tried manytime but it didnt work.It works fine on lan network.so plz help.Thanks

[duct tape]

You need to know the external IP address of the target computer, and then set up the router so that it forwards all requests on the port you are using to the target. It should then be accessible through the internet.

[shoyru_master_11]

GOOD

[shoyru_master_11]

I used regedit to put temporary COSMOKEY keys on not as harmful

[shoyru_master_11]

netcat error

[NetDex]

My Anti virus (PC Tools) blocked it.

[teh_noob]

http://www.securityfocus.com/cgi-bin/index.cgi?c=toolcomments&op=display_comments&ToolID=139&expand_all=true&mode=threaded

go there for netcat :D

[teh_noob]

SUPER AWESOME 'IBLE!

[pedro_33165]

nc.exe is a .tmp file, my antivirus got rid of it. and nc.bat is a webpage.

[admiral001]

when I click on the files in this Instructable, it tries to download a tmp file.

[hg341]

tell it to save as "all files" then rename it "netcat.exe" or "putty.exe" it did that to me to^{are you useing ie8}

[B.F.L.M]

if you save it as netcat.exe, then nc.bat wont work(if you use it) you should save it as nc.exe

[adaviel]

If you got here via google "download netcat", see the comments on "intro". nc.bat creates a backdoor on your computer if you run it.

[rearthur2003]

-d is for stealth which will make the program run in backgraound and -t is for telnet mode it allows other machine to telnet to it

[Psychic Master]

im having trouble how do you use the window that pops up after you open PuTTY?

[Psychic Master]

and about 15 sec after i open the window it says "connection timmed out"

[wee_man]

Yea hi if i port forwarded port 4444 to a computer on my network could i remotely access it from a computer off my network?

[duct tape]

Yes. But I'd put a password or something on it. You would also need a static ip or a domain name from dyndns.com. What I do sometimes is make my computer into a file server with HFS. Just google it and you will come up with an idea...

[wee_man]

yea i have a doman name i auctly have game and webservers and all that stuff running on it umm with this is their a way i can add files like from remote computer > host ??

[duct tape]

Of course! Please tell me more about your set-up.

[tgfmk2]

Rule no.0 never give away you ip adress on a site that teaches you how to hack

[duct tape]

This isn't the actual ip address - it is the network ip. It doesn't matter if someone knows this, unless they are on your network.

[ItsLinaxD]

When I downloaded nc.exe it was a .tmp file, so it didn't work. :o

[DavidRobertson]

Hey 192.168.1.103 is my ip address(or at least it seems so)

[themasterpyro]

i-am going to haaaaack youuuuuuu.

[mikemmcmeans]

ha you're not as smart as you try to be.
a "192.168.x.x" is the ip address behind his router. unless you also have the external ip (the one between your isp and you) , you cant do a single thing but hack your own router

[duct tape]

I think he was making a joke...

[MostlyHarmless]

Even with someone's ip you can't easily or readily hack them, a number of measures are in place "out of the box" on nearly every computer used nowadays. Regardless of whether or not they have a firewall, hacking is not as simple as script kiddies would have you believe.

[duct tape]

i'm pretty sure that he was just joking.