How to hide a file inside another

 Hiding files in Windows

Why the need to hide files?

Hiding your history?

The other day, a thought occurred to me. How can one hide sensitive information on a computer? The first thing that came to mind was the Hidden file attribute for files and folders, but anyone who knows how to can view those files, and if you’re using Windows XP like I am, it makes the job even easier by telling you that there are hidden treasures in the folder you’re in.

I’m aware that there are many ways to hide files, the methods include, but are not limited to the following;

1) Compressing the file

2) Compressing and encrypting

3) Using file hiding software like Partition Magic or Concealer

4) Placing the hidden files on a separate partition and restricting access to it.

Some of these options are pretty good, but what if you need to hide a file on a shared computer or what if you need to hide the file immediately without the need for additional software that costs an arm and a leg? This is what motivated me to do some Googling and what I found is quite interesting, it is actually possible to hide files in a relatively simple way without the need to purchase expensive software.


Warning, this may be a little over the top for newbie’s (or noobs as I prefer to call them) so don’t worry if you don’t understand this at first, I’ll try and make this as simple as possible.

The method I’m going to show you uses the copy command in command prompt or DOS.

Experienced users will probably think that this is not a very effective method because it is possible to read the headers of the file and figure out the contents, but hey, at least it offers some protection. Its not like we’re hiding files from the C.I.A, (or the C10’s as we call them in Zim) or something. This is just basic file hiding.

So what you need to do is simply copy the file you want to hide into another file. Yes, it’s possible; if you use the command prompt. I’ll first summarise the steps involved and then explain them.

  1. create an archive, preferably WinRAR and add the files to be hidden into the archive
  2. using cmd, copy the archive into another file
  3. To view the file, use WinRAR to open the file that hosts the hidden files and click on the archive you want.
  4. Sleep easy, your files are hidden……..

Hiding the files

Firstly, create an archive with the files to be hidden. You could call it Hidden.

Second, create a folder in the root directory to house your files. Call it Test.

Next, move the archive (Hidden) and the file that will host it (file123.avi) to the folder you created above (Test) (or any other folder, but make sure you get the path name right).

  1. Click start and then click run
  2. Type in cmd and press OK. This will start the command prompt.
  3. Type in “CD\”. This takes you to the root directory (usually c:\ )
  4. Type the following: “copy /b file123.avi + Hidden.rar file123.avi”

Replace “file123.avi” with the name of your host file and “Hidden.rar” with the name of your archive and its extension .The /b tells the computer to copy all the binary data I think……

That does the trick. The archive has been copied to the file you specified.

I’m not sure how you can un-copy or separate the files though, I’ll need to a little more reading on this.

Interesting note: A comment on a similar article says that if the above process is too much for you, you could consider developing an application that does that for you. I’m seriously considering this….I’ll update you on my progress.

>>Second point, use common sense, a 100MB jpg image is sure to raise suspicion, so use other file types if you’re going to be hiding large files e.g. avi, exe, vob etc.

In order to view the files, you could open the host file using WinRAR.

To do this you could do the following:

  1. Right click the application and choose the Open With option and select WinRAR
  2. Change the file extension of the file to .RAR and open the file

Possible  applications of the copy command.


The above information might get you thinking of sick ways to exploit that feature and if you are, I’m with you there, as long as it’s ethical that is.

Here are a few things I could think of that could be done.

  1. Use this to transfer executable files(or any other restricted file) over the college network. The assumption of course is that only the file extension will be scanned.
  2. Hiding files in plain sight
  3. Secret communication.