In the NTFS file system When you create a new file , one unnamed default stream is created to store all data written to the file.Since NTFS file system in Windows 2000 or above supports Alternate Data Streams,you are allowed to create additional streams for text file. All data stored in the addition streams will be hidden and no one will be able to read the data. This may be useful when you would like to hide some sensitive info from being read by others when sharing the file to public.

What is Alternate Data Stream??

In simple words it is a facility to hide data behind data.

This can be used to hide malicious virus files behind other text or graphic files.

How to hide text file behind a text file??

Here is an example to hide text file behind a text file.

1> Create a text file using Command Prompt.

Go to Run, type cmd. Change the directory if you want.

Type

echo visit etricks.in for cool computer tricks > etricks.txt:hidden

Here hidden is alternate data stream created along with etricks.txt

2>To enter data using that hidden data stream type

notepad etricks.txt:hidden

You will see a popup saying “Cannot find the C:\etricks.txt:Hidden.txt file”. Do you want to create a new file?”.

click yes.

3> Type anything you want and press ctrl+s.

4> Now go to C drive. There won’t be any such file. You will see etricks.txt only.

5> To view data in hidden file go to cmd and type

notepad etricks.txt:hidden

and now you can see the data in etricks.txt:hidden.txt

How to hide .exe file behind txt file??

Procedure is quite similar to the above one.

c:\> type c:\windows\notepad.exe > hello.txt:note.exe

Here notepad.exe is copied to hello.txt:note.exe

Now when you copy hello.txt, note.exe is also copied along with it.