Your complete introduction to Capture The Flag competitions
Welcome to the Islander Cyber Society CTF Training Gym! This guide will help you get started with Capture The Flag (CTF) competitions. Whether you're completely new to cybersecurity or looking to develop competitive skills, this guide will walk you through everything you need to know.
CTF competitions are the perfect way to learn cybersecurity through hands-on challenges. You'll solve problems, exploit vulnerabilities, and develop skills that translate directly to real-world security work.
Capture The Flag (CTF) is a type of cybersecurity competition where participants solve security challenges to find hidden "flags" (text strings that prove you completed the challenge). Think of it as a puzzle-solving competition where the puzzles are security problems.
The most common format. Challenges are organized by category with point values. Solve challenges in any order to earn points. Higher difficulty = more points.
Teams run vulnerable services and must patch their own while exploiting opponents' services. More advanced format requiring team coordination and defensive skills.
Why CTF? CTF competitions are the best way to develop practical security skills. You'll learn by doing, not just reading. Skills learned in CTF directly translate to penetration testing, security research, incident response, and software security engineering.
Don't worry if you don't have all these skills yet! CTF is a learning process, and you'll develop these through practice.
Basic command line navigation, file permissions, processes, and shell scripting.
Start Here:
• Learn Linux basics on OverTheWire Bandit
• Practice with Ubuntu or Kali Linux
• Master basic bash commands
Python is essential for CTF. Understanding code helps you write exploits and analyze programs.
Start Here:
• Learn Python basics (variables, loops, functions)
• Understand reading/writing files
• Practice network requests with requests library
Understanding how computers communicate: TCP/IP, HTTP, DNS, and common protocols.
Start Here:
• Learn OSI model basics
• Understand HTTP requests/responses
• Practice with Wireshark
HTML, JavaScript, HTTP, cookies, and how web applications work.
Start Here:
• Build a simple website
• Learn browser developer tools
• Understand client-server architecture
Understanding encryption, hashing, encoding, and common ciphers.
Start Here:
• Learn encoding vs encryption
• Practice with CyberChef
• Understand common hashing algorithms
Persistence, curiosity, and systematic thinking. CTF requires creative problem-solving.
Develop Through:
• Breaking problems into smaller steps
• Reading writeups after solving
• Asking questions and collaborating
CTF challenges are organized into categories. Understanding these categories helps you know what skills to develop and what to expect in competitions.
Exploit vulnerabilities in web applications like SQL injection, XSS, CSRF, and authentication bypasses.
Common Challenges: SQL injection, cross-site scripting (XSS), SSRF, authentication bypass, file upload vulnerabilities
Tools: Burp Suite, curl, browser DevTools, sqlmap
Exploit vulnerabilities in compiled programs like buffer overflows, format strings, and heap exploitation.
Common Challenges: Buffer overflow, return-oriented programming (ROP), format strings, heap exploitation
Tools: GDB, pwntools, checksec, ROPgadget
Analyze compiled programs to understand how they work, find hidden functionality, or extract secrets.
Common Challenges: Disassembly, decompilation, anti-debugging, obfuscation, malware analysis
Tools: Ghidra, IDA Pro, radare2, x64dbg, strings
Break or exploit weak cryptographic implementations, from classical ciphers to modern encryption flaws.
Common Challenges: Classical ciphers, RSA attacks, AES misuse, hashing vulnerabilities, weak randomness
Tools: CyberChef, RsaCtfTool, hashcat, Python cryptography libraries
Investigate files, memory dumps, network captures, and digital artifacts to find hidden information.
Common Challenges: Steganography, file carving, memory analysis, network traffic analysis, file system analysis
Tools: Wireshark, Volatility, Autopsy, binwalk, exiftool
Challenges that don't fit other categories: OSINT, programming puzzles, trivia, and unique challenges.
Common Challenges: OSINT (Open Source Intelligence), programming, scripting, puzzle-solving, reconnaissance
Tools: Google, Python, various scripting languages, creativity
Install the essential tools you'll need for CTF challenges:
Start with beginner-friendly challenges to build confidence:
Work through our structured training modules in recommended order:
Learning CTF is easier with a team:
Don't jump into hard challenges immediately. Build confidence with easier problems, then gradually increase difficulty. Every expert started as a beginner.
After solving (or attempting) a challenge, read writeups to learn different approaches. You'll discover new techniques and tools you didn't know existed.
Keep notes on what you try. This helps you avoid repeating failed approaches and creates valuable reference material for future challenges.
It's tempting to try everything, but focusing on one category helps you build deeper expertise. Master web exploitation before moving to binary exploitation.
Regular practice is more effective than cramming. Solve a few challenges each week rather than binging before competitions.
CTF challenges are meant to be difficult. Spend time thinking about the problem before looking for hints. The "aha!" moment is worth the struggle.
Searching for error messages, tool usage, and vulnerability types is a crucial skill. CTF is open-book; research is part of the challenge.
Work with teammates during competitions. Explaining your approach to others helps solidify your understanding and you'll learn from their perspective.
Start with challenges marked "easy" or "beginner." Hard challenges can be demotivating when you're just starting. Build up your skills progressively.
The challenge description often contains crucial hints. Read it multiple times and pay attention to every word before diving into the problem.
CTF challenges require persistence. If you're stuck, take a break and come back later. The best learning happens when you struggle through problems.
After failing or solving a challenge, review what worked and what didn't. Read other solutions to see different approaches. Every challenge is a learning opportunity.
You now have the foundation to start your CTF journey. Choose your next step: