Teach children about cyber security by playing Capture the Flag

Since the beginning of my studies (yes, we are going way way back) I have given quite some guest lectures at primary and secondary schools. Where it mainly started to make girls more enthusiastic about technical / IT studies by giving lessons about web & app design (within VHTO’s DigiVITA project), I actually liked it so much that I still love and enjoy these guest lessons. Now they are no longer about HTML and CSS, but about cyber security and safety on the internet.

As part of these guest lessons, I also organize the Summer School every year, where more than 50 children between the ages of 8 and 15 can choose between two different areas: the social engineering game and a technical Capture the Flag. Where the social engineering game was aimed at children from 8 to 11 years old, older children from 12 years old could get started with the Capture the Flag. A Capture the Flag is an online competition where teams have to look for ‘flags’. These flags are hidden in, for example, a web application; you will only see them when you have successfully solved a challenge. Security experts or ethical hackers use this to practice hacking, but it also works well in school classes because of the game element. You will soon realize how easy it is to get in and will therefore choose a stronger password or enable two-step verification.

I wrote the platform for the Capture the Flag in Laravel. Since different ages had to work with different skill levels, I wanted to make the platform as simple as possible (and I couldn’t find that in existing platforms). Besides, I don’t mind coding from time to time :). In order to test the platform and the challenges in all ways, we played a practice round with many security specialists. If you still find something, please let me know!


You can register as a new team on the landing screen. Do not forget to choose an icon that suits your personality well (hehe). A CTF code was set as a requirement in order to place students in the right class room. Only students in your class room will be placed on the score board.

Example challenge

On the left screenshot an overview screen with several categories is shown. At the moment these are hacking, forensics, crypto and coding. Per category, a record is kept of how much you have already solved. On the right screenshot you can see how the challenges are displayed per category. In a list, where the title is the link to the challenge, the challenges are sorted by difficulty. There is an input field for each challenge: the flag found must be entered here.

Example challenge
Example challenge

The above screenshots show two challenges: ‘Common password’, where you have to try to log in with frequently used usernames and passwords and ‘Doors’, a challenge where you have to see which ports are open on a server in order to gain entry. Let’s see how to solve the first challenge. By clicking on the link, you will find a Wikipedia page about the most commonly used passwords. You should try this manually (or automatically if you’re a 1337 hacker). However, you don’t know the username, but if you read the error message correctly, you will easily find out. Do you have the username and password correct? Then you get a flag.

Gevonden flag
Punten verdiend

On the left you see the flag. If you enter this in the input field below the correct challenge name (second screenshot), you will receive points (third screenshot) and the challenge will be indicated as ‘solved’.


Do you also want to use this in your class or with your kids? At https://ctf.hackchallengesforkids.com you can visit the CTF environment including about 30 challenges (and more to come!). You will need a CTF-code to play it with your students. You can request this by sending a Twitter DM, a LinkedIn message or by sending an email to ctf [at] hackchallenges [dot] nl .