NahamCon EU CTF 2022 Writeups

CTFtime event link: https://ctftime.org/event/1843

Writeups

• Web:
  • Byepass
  • Use After Exit (Unsolved)
• Warmups:
  • Way 2 Basic
  • Hashstation
  • catscii
  • Arjeebee
  • Banjo
  • Baby’s First Heartbleed

Background

• Starts: December 16th, 12:00 PM PST
• Ends: December 17th, 12:00 PM PST

Categories:

• Warmups
• Web
• Binary Exploitation
• Reverse Engineering
• Cryptography
• Mobile
• DevOps
• Cloud
• Miscellaneous
• Hardware/RF
• Networking
• Scripting
• Web3

Overview

• Solved: 9
• Points: 450
• Rank: 238/1667
• Overall Difficulty To Me: Very Hard

What I’ve learned in this CTF

• Web:
  1. RCE(Remote Code Execution) via File Upload & Blacklisted Extensions Bypass (Byepass)
  2. Use After Exit (Unsolved)
• Warmups:
  1. Converting binary data to ASCII text (Way 2 Basic)
  2. Cracking SHA256 Hash via CrackStation (Hashstation)
  3. Linux Reading File via cat (catscii)
  4. Converting RGB Color To Hexadecimal (Arjeebee)
  5. Linux List Strings via strings (Banjo)
  6. Leaking The Flag via No Input Validation (Baby’s First Heartbleed)