HTB - Debugging Interface - Intro to Hardware Hacking


Home Blog Projects Books	Categories: ctf ¹ projects ¹ Tags: c++ ³ cmake ¹ game ² hardware ¹ htb ¹ reversing ¹ rust ¹ sfml ² HTB - Debugging Interface - Intro to Hardware Hacking March 30, 2024 Table of contents: Challenge description Initial findings Decoding the digital signal YELLO!!! Long time no see…BUT NEW SERIES!!!!! CTF writeup. I started the Intro to Hardware Hacking on HackTheBox, this is gonna be the first writeup about the debugging interface challenge. Challenge description “We accessed the embedded device’s asynchronous serial debugging interface while it was operational and captured some messages that were being transmitted over it. Can you decode them?” Initial findings When you first download the given files, its in a zip. After i extracted it, it gave me a .sal file. I’ve never seen this kind of file extension so i did some searching on the net. Searched for like 10 mins i didn’t find shit, most of the sites pointed to its being a mysql extension but no luck with trying to run it with mysql. I almost scrolled to the bottom of the search results and found a website with a title like and description like this: Seems its some kind of external debugging tool and it also has a software called Logic. Decoding the digital signal After installing the software i was prompted to import a file so i was able to import the .sal file. On one channel I was able to see a digital signal in a time frame. This wasn’t the first time ive seen a program or an output like this. Like a month ago i was watching embedded reversing videos and in one of them there was something related to this and i remembered he was switching the bitrate of the signal. So i went down that route, i found something on the websites doc about how i can find out, calculate the bitrate. Theres an extension in the program which calculates the average frequency of the signal. It was around 31.23kHZ, i converted the kHZ to bits/s and it was around 31230/s. I changed the baud rate to this and the bits to represent ascii characters and i was able to see the flag. BOOOOOOOM————–

YELLO!!!

Long time no see…BUT NEW SERIES!!!!! CTF writeup.

I started the Intro to Hardware Hacking on HackTheBox, this is gonna be the first writeup about the debugging interface challenge.

Challenge description

“We accessed the embedded device’s asynchronous serial debugging interface while it was operational and captured some messages that were being transmitted over it. Can you decode them?”

Initial findings

When you first download the given files, its in a zip. After i extracted it, it gave me a .sal file. I’ve never seen this kind of file extension so i did some searching on the net. Searched for like 10 mins i didn’t find shit, most of the sites pointed to its being a mysql extension but no luck with trying to run it with mysql. I almost scrolled to the bottom of the search results and found a website with a title like and description like this:

search_result

Seems its some kind of external debugging tool and it also has a software called Logic.

Decoding the digital signal

After installing the software i was prompted to import a file so i was able to import the .sal file. On one channel I was able to see a digital signal in a time frame. This wasn’t the first time ive seen a program or an output like this. Like a month ago i was watching embedded reversing videos and in one of them there was something related to this and i remembered he was switching the bitrate of the signal. So i went down that route, i found something on the websites doc about how i can find out, calculate the bitrate. Theres an extension in the program which calculates the average frequency of the signal. It was around 31.23kHZ, i converted the kHZ to bits/s and it was around 31230/s.

digital_signal

I changed the baud rate to this and the bits to represent ascii characters and i was able to see the flag.

changing_baudrate

BOOOOOOOM————–