I love ROI-driven solutions and this post is about one of them. My personal cybersecurity consulting practice exposed me to many different types of ‘IT security’ jobs over last 13 years and today I will describe one of them…

Nearly a decade ago one of my clients contacted me saying that they got a USB key that belonged to their client, and their client was interested in regaining the access to the device’s content after they forgot the password.

Hmm interesting…

This was not your random USB key, but a removable device that was specifically designed to encrypt its data by default. As an input, I got a forensic ‘image’ of the USB key, plus some basic info about its vendor, and that was it – so I quickly googled around, and immediately realized the company that produced it was out business for a while…

Before I could even begin I was shot down.

To access the content of the device one needed to run their software (that was luckily present on the key in an unencrypted form), provide the password, and then the actual content of the key would be decrypted and mounted as a separate Windows device. I may not be remembering everything as it was, but the bottom line was that I got an image of an encrypted USB key and had to find a way to crack its password.

The software handling the decryption process was a mess. It was on the complexity level of today’s Rust, Go, Nim binaries – written in a language that was not very commonly used, very high-level, lots of dependencies and hard to analyze statically – definitely no dedicated tools to support analysis (I know I am vague, but it was long time ago – it could have been Visual FoxPro or something like this, I really don’t remember!).

After a few hours of static analysis in IDA I threw a towel and decided to take a different approach. I was hoping that a person that was using the encrypted key was using some simple password that is easy to remember.

So, I build a dictionary of popular English words, then ran that weird decryption software, and finally wrote a very rudimentary AutoIt script that would fetch a word from a dictionary text file (dictionary) one by one, save it to a log file in each iteration, then push it to the UI control of that software that was handling the password input, then send a key that would simulate someone pressing an ENTER key…

Luckily, the software didn’t have any anti-brute-force mechanisms built-in so I just let it ran over night. To my surprise, next morning I discovered the password was cracked!

It was a simple 5- or 6- character long English word, if I remember correctly and once I found out I was immediately ecstatic! I quickly relayed the message to my client, they did so to theirs, and we all ended up being happier and richer that day…

Is there a lesson there for us?

YES!

Sometimes stupid solutions work. You don’t need to understand everything. It’s good to be driven by ROI principles. The art of ‘hacking’ is elusive.