Flare-On 7 2020 Write-Ups

This year I participated in Flare-On 7 (2020) and I wanted to share my thoughts about this great CTF.

Overview

The challenges were great this year, I learned a lot and they were pure reversing. For anyone wants to strength his reversing skills, flare-on is a great choice. This is like an intensive reversing course for six weeks that you will suffer and enjoy both together.

Solutions

I separated my solutions into different pages to make it more readable:

  1. Challenge #1 - Fidler
  2. Challenge #2 - garbage
  3. Challenge #3 - wednseday
  4. Challenge #4 - report
  5. Challenge #5 - TKApp
  6. Challenge #6 - codeit
  7. Challenge #7 - re_crowd
  8. Challenge #8 - Aardvark
  9. Challenge #9 - crackinstaller (in progress..)
  10. Challenge #10 - break (in progress..)
  11. Challenge #11 - rabbithole (in progress..)

What I Have Learned?

Writing writeups is important!

I wrote write-ups because I find it very useful. As a hobby chess player, it is very important to investigate your games and understand what could you do better and how to improve for next time. Writing the write-up, without pressure, can help to think about other ideas you could do. Another thing is tBecause you will find new way to solve what you tried and learn new techniques. There are number of write-ups about it but my friend Shaked Reiner (@ShakReiner) and Itay Cohen (@megabeets_) created a great website explained.re with nice write-up.

Hidden Visual Basic code (p-code)

In challenge #4 I encounter something called p-code:

As each VBA line is entered into the VBA editor, it is immediately compiled into p-code (a pseudo code for a stack machine) and stored in a different place in the module stream. The p-code is precisely what is executed most of the time.

You can see the code in Visual Basic but it actually doesn’t show you some of the code that exist in the p-code.

Security researcher interested in reversing, solving CTFs, malware analysis, penetration testing and DevOps security (docker and Kubernetes)