# Challenges
Capture the flags. Prove your skills.
107 challenges found
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KidLab
A colorful web app for kids with user accounts and a reporting system. But who is reading those reports?
Inca Empire
The Inca Empire web portal renders user input in unexpected ways. What if the template engine processes more than it should?
HTTP
Not everything is visible on the surface. Look closer at how the server responds.
Hangman
A classic game of Hangman. The word might be simpler than you think.
Forbidden 1
Access denied. The admin page is off limits.
Executioner 3
The final executioner. Almost everything useful is blocked. Almost.
Executioner 2
The executioner returns with tighter restrictions. Spaces and slashes are no longer your friends.
Executioner 1
A command execution service with a filter. Find a way to run what you need despite the restrictions.
Dev Academy
NovaDev Academy just launched their new website. They are running a suspiciously specific version of PHP.
Decimals
A number that is simultaneously less than and greater than a threshold. PHP has some interesting ideas about numbers.
Curse Hunter
A cursed API requires a specific identity to reveal its secrets. Can you become someone you are not?
CTF Market
Welcome to the CTF Market! Browse products, apply coupons, and upgrade your account. Every good shop has its weak spots.
Predictable Randomness
Randomness is only as strong as the algorithm behind it.
Circus 2
String comparison protects the flag. But not all comparisons behave the way you expect.
Circus 1
Two values must produce the same hash, but they cannot be equal. The comparison operator holds the key.
By Proxy
A web proxy forwards your requests to an internal service. What happens when you control where it goes?
Bear Ninja Cowboy 4
The game adapts to your play style. Can you outsmart an opponent that learns from your moves?
Bear Ninja Cowboy 3
The computer picks its moves using a random number generator. But is it truly random?
Bear Ninja Cowboy 2
Another round of Bear-Ninja-Cowboy. The rules seem familiar, but the input handling has a subtle flaw.
Bear Ninja Cowboy
A rock-paper-scissors variant where Bears, Ninjas, and Cowboys battle it out. Win 30 rounds in a row to claim the flag.