Showing posts from April, 2018

The Audacity of Some CTFs

2021 Update : This is currently the most read post on our blog. Chances are that you are here because you are working on an audio challenge. If you see something looking like a digital signal, be sure to also check out our Radioactive Man write-up. I have stumbled across a few audio files while competing in CTFs over the last few years and I thought covering spectrograms would make a nice and quick blog post. Flags can manifest themselves in many ways when dealing with media files. One of the most common ways I have seen is by hiding them, or clues to find them, in the file's audio spectrogram. According to wikipedia: "a spectrogram is a visual representation of the spectrum of frequencies of sound, or other signals, as they vary with time." Basically, it is a method to visualize sound and signals. I first learned that you can embed hidden messages and images in a spectrogram when a friend showed me an image from an Aphex Twin song some years ago. Equation by

Hello World

Welcome Thrillhouse Group is a hacking team based out of North Carolina. We do CTFs and writeup some of our findings. You can find me on twitter @strupo_ - strupo_