What is CTF in cyber security?
A capture the flag (CTF) contest is a special kind of cybersecurity competition designed to challenge its participants to solve computer security problems and/or capture and defend computer systems.
CTF (Capture The Flag) is a kind of information security competition that challenges contestants to solve a variety of tasks ranging from a scavenger hunt on wikipedia to basic programming exercises, to hacking your way into a server to steal data. In these challenges, the contestant is usually asked to find a specific piece of text that may be hidden on the server or behind a webpage. This goal is called the flag, hence the name!
Like many competitions, the skill level for CTFs varies between the events. Some are targeted towards professionals with experience operating on cyber security teams. These typically offer a large cash reward and can be held at a specific physical location. Other events target the high school and college student range, sometimes offering monetary support for education to those that place highly in the competition!
Types of CTFs
There are two main types of CTFs: Jeopardy-style and Attack-Defense-style.
Jeopardy-style CTFs are essentially a list of hacking challenges that you can complete for flags that are worth a certain number of points. These challenges involve exploiting a vulnerability or solving a programming challenge to steal a “flag”. Teams compete to see who can find the most flags and gain the most points under a time limit.
The hacking challenges in Jeopardy-style CTFs are often sorted by difficulty levels, so beginners can easily participate as well. There are often different skillsets that you can choose from, from cryptography, reversing, binary, web, programming, forensics, networking challenges to problems that are a mix of some or all of these skills.
A more advanced version of CTFs is the Attack-and-Defense-style CTF. In these competitions, teams defend their own servers against attack, and attack opponents’ servers to score. These CTFs require more skills to compete and are almost always done in teams. For example, the annual DEFCON CTF finals is an Attack-and-Defense-style CTF.