CTF: Beginner's Guide

Sumber: https://thehackersmeetup.medium.com/beginners-guide-to-capture-the-flag-ctf-71a1cbd9d27c

Apakah kompetisi Capture the flag(CTF)?

Dalam kompetisi CTF, bendera biasanya berupa cuplikan kode, perangkat keras di jaringan, atau mungkin file. Dalam kasus lain, kompetisi dapat berlanjut melalui serangkaian pertanyaan, seperti perlombaan.

Mereka bisa berupa peristiwa tunggal atau tantangan berkelanjutan — dan biasanya terbagi dalam tiga kategori utama: Jeopardy, Attack-Defense.

Kategori dari Capture the flag (CTF)

Attack-Defense

Gaya kompetisi ini jauh lebih mirip dengan permainan menangkap bendera di halaman belakang daripada gaya Jeopardy. Dalam jenis acara ini, tim mempertahankan PC tuan rumah sambil tetap mencoba menyerang PC target tim lawan. Setiap tim memulai dengan waktu yang ditentukan untuk menambal dan mengamankan PC, mencoba menemukan sebanyak mungkin kerentanan sebelum tim penyerang lawan dapat menyerang. Tim dengan poin terbanyak menang.

Jeopardy CTF

CTFs gaya Jeopardy memberi pesaing serangkaian pertanyaan yang mengungkapkan petunjuk yang memandu mereka dalam menyelesaikan tugas kompleks dalam urutan tertentu. Dengan mengungkapkan petunjuk, kontestan mempelajari arah yang benar terkait teknik dan metodologi yang dibutuhkan ke depannya. Tim menerima poin untuk setiap tugas yang diselesaikan. Semakin sulit tugasnya, semakin banyak poin yang bisa Anda peroleh setelah berhasil menyelesaikannya.

Kompetisi CTF online kemungkinan besar adalah gaya Jeopardy. Lebih mudah bermain solo dan membutuhkan lebih sedikit koordinasi antar pemain daripada kompetisi attack-defence.

Apa yang dilakukan di CTF?

Jika Anda belum pernah mengalami kejadian CTF sebelumnya, jangan frustrasi atau menyerah, karena kunci dari segala jenis peretasan adalah kesabaran. Meskipun ini terkadang merupakan hal yang sulit untuk dimiliki, satu-satunya cara untuk belajar adalah bertahan dan berlatih sendiri.

Tipe Challenge/Tantangan

Tantangan biasanya dibagi menjadi 6 kategori untuk CTF, jenis tantangan yang umum adalah:

• Web: Jenis tantangan ini berfokus pada menemukan dan mengeksploitasi kerentanan dalam aplikasi web. Mungkin menguji pengetahuan peserta tentang SQL Injection, XSS (Cross-Site Scripting), dan masih banyak lagi.
• Forensics: Peserta perlu menyelidiki beberapa jenis data, seperti melakukan analisis paket pada file .pcap, analisis dump memori, dan sebagainya.
• Cryptography: Tantangan akan berfokus pada mendekripsi string terenkripsi dari berbagai jenis kriptografi seperti Substitusi crypto, Caesar cipher, dan masih banyak lagi.
• Reversing (or Reverse Engineering): RE biasanya membutuhkan peserta untuk menjelajahi file biner yang diberikan, file weather PE, file ELF, APK, atau beberapa jenis biner yang dapat dieksekusi lainnya. Peserta perlu menemukan kunci dengan dekompilasi, membongkar menggunakan analisis statis atau dinamis, atau reverse engineering tool lainnya.
• OSINT: Ide OSINT adalah untuk melihat berapa banyak informasi yang tersedia untuk Anda dan memahami petunjuk yang tersembunyi dalam tantangan itu sendiri dengan bantuan google dan sedikit keterampilan pemecahan masalah. Jadi lebih banyak tool seperti detektif, dan tidak fokus pada enumarsi domain, dll.
• Miscellaneous: Segala sesuatu yang tidak tercantum selain yang masih relevan dengan Keamanan Informasi ada dalam kategori ini. Kebutuhan ini membutuhkan keterampilan Google-Fu. Singkatnya, anda bisa mengatakan semua hal bisa ditanyakan :) ..

Trik untuk menang CTF

Berlatih sendiri

Ada banyak cara untuk berlatih untuk kompetisi CTF. Banyak kontes lama akan mengunggah flag dan solusi mereka sebelumnya. Orang-orang juga sering memposting tulisan di blog keamanan mereka tentang tantangan dan teka-teki yang sangat menarik yang telah mereka pecahkan.

Follow the news

CTFs like to be trendy. Keeping up with what’s going on at other CTFs, security conferences, and the wider cybersecurity community can be important in giving you an idea on how to approach hacks and which vulnerabilities to try and exploit. If you see an interesting proof of concept hack or exploit online that you can replicate in your home lab, take the time to work through it and pick up new skills.

Build a toolkit

Before you even get to a CTF you should know what tools you need to win. As you do practice exercises and go to CTFs, keep a list of tools you find yourself using and keep them stored in one place on your computer. Find an approach that works for you and be sure that you spend the bare minimum time at a CTF downloading and researching tools you’ve used in the past.

Take care of yourself

Like at Hackathons, it’s important at a CTF to keep track of your personal well-being. If you need to sleep — do so.

Make some friends

Take time to get to the know the other teams at the competition. Be friendly and approachable yourself. Reciprocate and be nice to people who approach you but try and keep strategically important information close.

How to Get Started

If you’re brand new to hacking, then find a good course to teach you the skills. You can start by setting up a Kali Linux / Parrot Security practice lab, so you can get hands-on experience immediately.

When you’re ready, work through the CTF challenges, review the write-ups, and maybe even enter a competition. By competing in these competitions and following the challenges, you not only strengthen your knowledge and understanding of how the technologies work, but also how to select the appropriate responses to a challenge.

If you’ve never experienced a CTF event before, don’t get frustrated or give up, because the key to any type of hacking is patience. While this is sometimes a difficult thing to have, the only way to learn is to persist and practice on your own (see this post further down on how to practice) and maybe next time you’ll score first place! One thing you can try to do during your first CTF event, if possible, is to find an experienced team that’s willing to let you join them. Make sure you’re clear that this is your first CTF event and you’d love for them to show you the ropes.

What I would recommend you use at your first CTF, in order of easiest to most difficult, would be one of the following:

• Kali Linux

This distribution comes purpose-built for penetration testing. It’s packed with every tool imaginable and probably a ton more than you’ll never need to use.

• BlackArch

This distribution is based on Arch Linux but comes pre-built, much like Kali does, with tons of security tools.

• Arch Linux

This is a base Linux install that comes with standard Linux tools. If you choose this option, you’ll have to do the leg work of installing all the tools you can think of that you might need or at a very minimum ensure that you have access to an internet connection to allow you to quickly install the tools you require at the event.

Examples

If you are using windows then also don’t worry. What you can do is, you can install any of this OS in your VirtualBox Environnement and then Access the CTF through it and start solving the challenges

Also, here are some links that’ll help ya and tell you which tools to use for solving challenges more efficiently

• https://www.yeahhub.com/top-10-essential-ctf-tools-solving-reversing-challenges/
• https://github.com/JohnHammond/ctf-katana
• https://apsdehal.in/awesome-ctf/

CTF Etiquette!

Before you go on to playing CTFs (and having the time of your life!), here are a few sacred rules of CTF participation that you should keep in mind.

First, absolutely do not post solutions and flags online! The purpose of CTFs is to help people become better hackers through the mental struggle of solving challenges. Giving solutions away is denying the chance for others to learn.

On the other hand, you also should not try to google solutions or ask for flags online. You can ask for help, discuss with others or even collaborate in solving a challenge, but asking or googling for solutions takes away from the experience. Even if you try to understand the solution, it is not the same as working hard to and finally finding the answer yourself!

Last but not least “ ALWAYS READ THE RULES”.

CTFs are a great hobby that ultimately makes you a better hacker. In fact, many of the most skilled hackers came from CTF backgrounds. I hope you’ll find the experience rewarding as well. Best of luck and have fun!

Resources

Tools and Resources to Prepare for a Hacker CTF Competition or Challenge

• https://resources.infosecinstitute.com/tools-of-trade-and-resources-to-prepare-in-a-hacker-ctf-competition-or-challenge/#gref
• TryHackMe | Learn Cybersecurity - * https://tryhackme.com/
• Hack The Box |Penetration Testing Labs - * www.hackthebox.eu
• Hacksplaining - * https://www.hacksplaining.com/
• Practice CTF List / Permanent CTF List - https://captf.com/practice-ctf/

Referensi

• https://thehackersmeetup.medium.com/beginners-guide-to-capture-the-flag-ctf-71a1cbd9d27c