Down Memory Lane: Tamal Chakravorty, Ericsson Global Services India

This one incident that I very fondly remember was one of the biggest accomplishments in my first job. I was working with Zenith Computers as a customer support executive and some of the clients I had to deal with were some of the biggest brand names in India.

A large petroleum company in India wanted to protect confidential files in DOS and restrict their access. In the 90’s most companies either used DOS or Novell. We didn’t have the concept of password protection and hiding directories in DOS was not an easy job either. But I was in my early 20’s, and the enthusiasm to prove myself was huge.

I was a programmer at that time. In those days, one needed to have a fair knowledge of ASCII codes to be a coder.  It was while doing some programming for a large FMCG company that I came across something called the Ctrl+Alt+255. This combination basically creates a blank directory, that is, a directory name which just looks like a “space” as if you created a directory by pressing the space-bar. I realized that if someone were to break into my directory and try to access or tamper files they would end up seeing everything apart from this directory because it showed up as blank.

But one can create a hidden directory in DOS and knowing the combo key can help them get into the directory and retrieve a file. So, I roped in a colleague. We were trying various things and one day he just had this idea to take the entire dump of the directory in the text file and print it. The idea was that if we could study the text, it would somewhere show us the hidden combo key characters as well.

But it didn’t happen. So he deleted all the lines and in front of the blank he wrote two words: Change Directory or CD and added a space and turned the .txt file into a .bat file. The fun is that you can run a .bat file in DOS and it automatically executes the command which can then do a “change directory” into that blank directory. This eliminated the dependence on one person in the organization, and also led to a satisfied customer.