How to Hide Executable Code in a Text File using Cloaking and Alternative Data Streams

Hacker Basics: How to Hide an Executable File Inside and Text File

Did you know that hackers can hide an executable file inside of a text file using a technique that uses something called data streams to trick a computer system from seeing text and or executable written in an alternate data stream inside a common text file.

I was pretty impressed the first time I watched someone demonstrate this. I was like, NO WAY! I really thought that this was some wizard level hacker stuff.

I’m no wizard level hacker, although I aspire to be, but I should be good enough to show you how to embed a simple calculator app inside a text file using an alternate data stream.

A big thank you to Cyber Security Expert, Malcolm Shore who presented a similar example in his Cyber Security Foundation online course I recently completed.

How Do Alternate Data Streams Work?

Way back in the old Wild West days when we had the DOS operating system, files used to be simple strings of data. Files are read btye by byte.

Later, in the NTFS file system, files are complex structures. NTFS files at a minimum contain a section called $Data where data is read by an application. $Data is the Data Stream.

Files may have many other sections or streams other than just the $Data section. This is what we call “Alternate Streams”.

THIS IS IMPORTANT: Windows only recognizes data in the $Data section so any data we put in an alternate data stream is not read by the Windows Operating System. We cloak data we want to hide in an alternate data stream. That’s the basics of how this works.

The data we are hiding could be a malicious malware payload or encrypted espionage message for our spy ring but in this example, it is just the simple calc.exe file you can find on any Windows PC for the last 20+ years.

Creating an Alternate Data Stream in a Text File

The screenshot below shows the three (3) files we’ll be using in this demonstration.

  • Simple text file with some string data.
  • calc.exe application or executable binary file
  • Secret text file with some string data

We can see the size of the text file is just 1 KB and the calc.exe file is 897 KB.

If we open the text-data.txt file with Notepad we’ll see just a simple line of text and the same with the secret-data.txt file.

To hide our secret message inside the the text data file, we’ll use this command line command.

C:\text\>type secret-data.txt > text-data.text:hidden.text

Screenshot of Alternate Data Stream: Insert Hidden Text

Below is a screenshot of the command line command “type” that we used in this example to insert our secret-data.txt file into an Alternate Data Stream inside of another text file.

If we type the command “more” we can look for the secret message.

The screenshot below shows the text file that contains our hidden text being opened in Notepad where we can’t see the hidden text we saved to the file. If we type the command line command below, we can read the hidden text we wrote to our Alternate Data Stream by keying in on the specific data stream.

c:\test>more < text-data.txt:hidden:text

Hiding an Executable Inside a Text File

Hiding an executable file inside a text file using the exact same Alternate Data Stream technique we just used in the the Secret text file example above but this time we’ll simply replace the Secret text file with the Windows Calculator application executable file.

The screenshot below shows the command line command to save the calc.exe file in an Alternate Data Stream in side our target text file.

Notice this time, the Alternate Data Stream is named “mycalc.exe”. Don’t get to hung up on this, it is just a name that is basically meta data that is saved with the data that we can use to filter the data we get out of the file. I hope that makes sense.

Important to note at this point that the file sizes didn’t change when we inserted the calc.exe file. It is still showing 52KB.

How to Execute a File Saved in an Alternate Data Stream

To execute a file you’ve stored in an Alternate Data Stream, we’ll need to use the wmic command as is done in the following example.

c:\test>wmic process call "c:\test\text-data.txt:mycalc.exe"

As you can see from the working example above, I was able to embed the calc.exe file inside as well as text file and a secret message.

If the data is text we just need to indicate which stream we saved the data in to retrieve it.

If the data we hid was an executable file, we’ll need to use the Windows “wmic” command line command to call the executable from inside the text file by keying in on the Alternate Data Stream name.

In summary, the technique is crazy easy to pull off without any 3rd party hacking tools. It just requires a little Windows Operating System inside knowledge but is something every good hacker should know.

I hope this helped somebody!
~Cyber Abyss

How to Build Your Own Website Uptime Monitoring Script using VBScript: Part 1

Website Uptime Monitoring: The Basics

There are lots of website uptime monitoring services out there but all the components you need to build your own website monitoring tool can be found in good ole’ Microsoft VBScript.

Stop laughing, I’m not kidding!

In this article, I’ll share with you some scripts and tips I’ve used successfully in the past for monitoring website uptime even if your website is running in a complex load balanced enterprise environment which some of mine are.

VBScript Components for Uptime Monitor

Most people don’t know that VBScript can make Ajax HTTP calls but it can.

We will use VBScript’s ability to make Ajax HTTP calls to our website to see if it responds then put some simple logic around that response to log the results in a text/csv file.

It really is amazingly simple once you get all the code components together.

The ISWebSiteUp Function

The ISWebsiteUp function in my code example takes a URL string and makes an Ajax HTTP call to see if we get a HTTP code 200 or 404 returned meaning website loaded OK.

Once we get our 200 or 404 HTTP response code that, script returns true in the form of a text message box or if script times out you’ll get a false in an error message box.

You might be saying to yourself about now, what about the 404 response code for page not found. Yes, you might want to add some more code to handle that differently than a 2oo OK response but for this script, we just want to know if server is up. If we are pointing to a page at the root of a domain, we don’t typically get 404 errors in reality.

The Script Code

To use this code, copy it in to a text file and save it with a .vbs file extension for VBScript. Once you have the .vbs file, double click on it. You will see the message box with the message, “is up” or “is down”. A super simple example for our core application.


'isWebsiteUp: Takes String URL 
'isWebsiteUp: Returns strMessage in Message Box
Function isWebsiteUp(strURL)

	On Error Resume Next

	Set http = CreateObject("MSXML2.ServerXMLHTTP")
 	'Set http = CreateObject("Microsoft.XmlHttp")
	http.open "GET", strURL, False
	http.send ""

	'Only check for error of the HTTP Get request for 200 or 404 code returned. If any status is returned then the server is up
	if http.responseText <> "" AND err.number = 0 then
		'Commented out showing the response text. Use this for troubleshooting or exploring.
		'msgbox(http.responseText)
		isWebsiteUp = true
		strMessage = "is up"
	else
		isWebsiteUp = false
		strMessage = "is down"
	end if
	Set http = Nothing	

	msgbox(strURL & ":" & strMessage)
	err.clear
End Function

call isWebsiteUp("https://www.google.com") 

What the Web Server Sees in the HTTP call: WinHTTPRequest User Agent

The VBScript Ajax HTTP call to the web server presents itself as a web browser asking for the home page.

In the server logs a server admin may see this “User Agent” in their logs.

Mozilla/4.0 (compatible; Win32; WinHttp.WinHttpRequest.5)

Script Errors & Blocked HTTP Calls

This script works out of the box. Google is the most open website in the world in terms of IPs that their servers accept traffic from as they are in the business of collecting data about everything including every system that connects to it.

Other web servers, like ones I run, may not be so forgiving. Many server admins use many tools at their disposal to filter HTTP request at various levels.

Here are some examples of tools Windows Server Admin have at their disposal to block or filter your script from connecting to their web servers.

Windows Server Admin Tools for Handling HTTP Traffic

  • Firewall IP Restrictions (Window Server Admin)
  • HTTP Response Filtering (IIS Application Server Admin)
  • IP Restrictions (IIS Application Server Admin)