Serial Logs Writeup
Cyber Apocalypse 2021
Solved by : Nigamelastic
.sal
files are saleae logic analyzer files.- I got this as reference https://dystopia.sg/allesctf20-PWNkemon/ so i downloaded the sla logic analyzer https://www.saleae.com/downloads/
- from here after installing, i opened the sal files which i could and then the following:
- I imported the value i am pretty sure if i find the right analyzer it should work
- by far for this challenge async serial works the best
- challenge states raspberry pi which has a baud rate of 115200
- after some pondering i realized that there are some errors in parity on fixing them and using the
115200
in async serial we get the hex converting which gives us this:
https://www.dropbox.com/s/ztqoa16wvp6rvf6/message.txt?dl=0
- found this : https://6e726d.github.io/Challenge/Ekoparty15/
- this writeup explains how to get the baud rate
- open the SAL file and zoom
- zoom
- zoom
- zoom
- until you see the smallest unit of the digital wave then measure it: as its 13.498
- since it is in μ we will divide it by 1000000
- so 1000000/13.498 = 74085.049637
- I obviously used 74000 as bit rate, converted the hex to ascii with the tool itself and it gave me the flag:
CHTB{wh47?!_f23qu3ncy_h0pp1n9_1n_4_532141_p2070c01?!!!52}