Interest meeting · Sep 9 · 3:45 PM · W431
Creek Cyber

Compete · Apr — May

CreekCTF

A beginner-friendly, community CTF hosted at Cherry Creek High School with creative challenges and a welcoming atmosphere

★ We host this

Event Information

Date:
Annually (April–May)
Duration:
After School, ≈ 3 hours
Format:
In-person
Location:
Cherry Creek High School
Team Size:
2–4 people
First Held:
2025 (8 teams)

Competition Features

Community Driven
Creative Challenges
Beginner Friendly
Fun Themes

About CreekCTF

CreekCTF is a community-driven Capture The Flag competition hosted at Cherry Creek High School. It emphasizes creativity, learning, and fun, and is designed to be beginner friendly while still engaging for experienced players.

First held in 2025 with 8 teams, CreekCTF runs once a year in April–May, after school, in teams of 2–4. Every school that comes plays free. The categories are the standard ones, but the problems are written rather than generated — each one has a story attached, and the easy end is genuinely easy on purpose.

Challenge Categories

Web Security

Exploit web applications and find hidden flags

Cryptography

Solve encryption puzzles and cipher challenges

Steganography

Find hidden messages in images and files

OSINT

Use open source intelligence to gather information

Reverse Engineering

Analyze programs to understand their functionality

Miscellaneous

Creative challenges that don't fit other categories

What Makes CreekCTF Special

  • Creative Storytelling

    Challenges often come with engaging narratives and themes

  • Community Focus

    Emphasis on learning and helping each other grow

  • Balanced Difficulty

    Challenges range from beginner to advanced levels

  • Unique Challenges

    Often features innovative problem types not seen elsewhere

Skills You'll Develop

Problem Solving

Creative thinking and analytical skills

Technical Skills

Programming, networking, and security concepts

Collaboration

Working effectively in teams under pressure

Example problems

Six problems in the style CreekCTF is written in, one per category, so you can see what you would actually be doing. These are illustrations rather than problems from a past year — the real ones are retired to the practice set after the event.

Flag format CreekCTF{...}

  1. Web

    Beginner

    Lunch Menu

    The cafeteria site loads each dish from /menu?item=1. The kitchen swears there are only twelve dishes.

    How you’d start: Change the number in the URL. Try 0, try 13, try -1. The lesson is that a value the page sends is a value you control, and the server has to check it rather than trust it.

  2. Cryptography

    Beginner

    Locker 214

    A note taped inside a locker door reads: FuhhnFWI{g0q7_uroo_brxu_rzq}. Nobody has changed the combination since 1997.

    How you’d start: Every letter has moved the same distance through the alphabet. Count the shift that turns 'FuhhnFWI' into something you recognise, then apply it to the rest.

  3. Forensics

    Intermediate

    Yearbook Photo

    A 4 MB JPEG of the 2019 club photo. It is nine people standing in a hallway. It should not be 4 MB.

    How you’d start: Run strings and exiftool over it, then look at the bytes past the end-of-image marker. Files can have things appended after they stop being an image, and archivers will still open them.

  4. OSINT

    Beginner

    Where Was This Taken

    A photo posted by a club account in April. No caption, no location tag, one window and one door number visible.

    How you’d start: Read the metadata first in case the camera saved a location. When it has been stripped, work from what is in frame — the door number, the trophy case, the reflection — and cross-reference against public photos of the building.

  5. Reverse engineering

    Intermediate

    Attendance Checker

    A small program asks for a password and prints 'not on the list'. You have the binary, not the source.

    How you’d start: Start with strings — often the answer is sitting in plain text. When it is not, open it in a disassembler and find the comparison that decides which message prints. You do not have to read all of it, only that branch.

  6. Miscellaneous

    Advanced

    Printer Jam

    A spool file recovered from the library printer. It renders as a blank page.

    How you’d start: The file is a program, not a picture — PostScript describes how to draw a page. Read the drawing commands and work out what would be on the page if the ink were not white on white.

Want to practise first?

Our CTF slide deck covers the categories above from the start, and picoCTF is free, always open, and written for exactly this level.

CTF slidespicoCTFCome to a meeting