Debugging Interface

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?

Solution

This WriteUp Solution is password protected by the flag of the challenge.

Flag:

On unzip we get debugging_interface_signal.sal which is a signal file. We can open it in Saleae Logic(Logic2) which you can download using this link Logic2

On opening the file with Logic2 we get the following interface: select 1F option from sidebar and then click Async Serial then select channel 0 and Enter the following values: To find bit rate scroll over the waveform in channel 0 and you will get the bit rate as 32.02μs which is in microseconds so transfer_rate=1000000/32.02=31230

now save it and click on terminal icon on the top right corner and you will get the flag.

The flag is HTB{d38u991n9_1n732f4c35_c4n_83_f0und_1n_41m057_3v32y_3m83dd3d_d3v1c3!!52}