HTB Cyber Apocalypse 2021 - Serial Logs | Hardware
Serial Logs
We have gained physical access to the debugging interface of the Access Control System which is based on a Raspberry Pi-based IoT device.
We believe that the log messages of this device contain valuable information of when our asset was abducted
Downloadable: logicdata.sal file
Solution
As shown in this picture, the bit rate will be 1 / (8.48 * 10 ^ -6) bit/second = 117925 bit/s
Logic Analyzer Software: Logic 2 Saleae
Analyzer: Async Serial with 117925 bit rate with the rest being standard settings
Clear text is shown in in the data tab, so that’s a really good sign that I used the correct analyzer.
While parsing through the data, I have noticed that the readable data will change from LOG Connection to an error that indicates a change in baud rate is coming up.
Due to the baud rate being changed, the data that comes after it will become gibberish again.
In order to fix that, I had to recalculate the baud rate.
As shown in this picture, the bit rate will be 1 / (13.46 * 10 ^ -6) bit/second = 74294 bit/s
The flag is located at the last few lines of the data.
