# Cyber Apocalypse 2021

## Serial Logs

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}
```