Debugging Interface
scenario: 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?
After we have downloaded the files through HackTheBox, we need to unzip the zip file
unzip Debugging\ Interface.zip
we have one file
debugging_interface_signal.sal
lets see the file type
file debugging_interface_signal.sal

we can see it is a zip file so lets unzip the file
unzip debugging_interface_signal.sal
we have two new files
digital-0.bin
meta.json
Looking through the meta.json
file, I could not find anything of use (yet), so redirect my focus on the digital-0.bin
file
Lets run strings
and see if anything pops out
strings digital-0.bin
we find an interesting header

After some googling it looks like SALESE
is a logic analyzer. So Lets download the demo and see if we can find anything interesting
https://www.saleae.com/downloads/
give it the approiate permissions
chmod +x Logic-2.4.13-linux-x64.AppImage
we can now load in the Debugging Interface.zip
zip file into the analyzer

This white block we can see is the data block, we can zoom in on the block by double clicking

we can see this is the signal we want to analyze, we want to start analyzing from the start of the data block,

we can see the data block start at 0.7ms, if we hover of the gaps in the data block we can see the bit rate

we can see the bit rate where I have highlighted is 32.2 ms, we need to find the bit rate (important), we can
1,000,000 / 32.02 = 31,230.48094940662 (31,230 Bits/s)
Now that we have the bit rate (31,230 Bits/s)
Next we want to go over to the analyzers -> Async Serial

as you can see we specified the channel we are on and the bit rate. click save
Now we have successfully decoded the data, Now we just need to find where we can access it from
on the right pane we should have a terminal button

Now we can view the data that has been captured, which holds the flag for this challenge

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