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:


  • 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:
Published on : 24 Apr 2021