Welcome to Mark's blog for Capture The Flag (CTF) enthusiasts

Friday, May 6, 2022

F1r5t Fl4g: A 30 minute CTF

Mission Brief
The goal of a Capture The Flag (CTF) is to collect flags, which are short snippets of text. More flags = more points.

Most CTFs have a flag format. If you think you've found something that follows the format, it might be a flag. For this CTF, the flag format is: FTC{sometexthere}.

Each flag is hidden within a challenge. A challenge can involve anything: analyzing firewall log files, decompiling malware, or even hacking into a server. Prepare to use your brain in strange and wonderful ways while looking for flags.

Here are five challenges for you to have fun with. Can you solve them in less than 30 minutes?

Challenge 1: Forensics.
Look at the ten lines below. Which is the real flag?
  1. FFC{rac00n}
  2. CTF{D1nosa4rs}
  3. FTC[N4rwh4l}
  4. FLAG{BUMBLEB33}
  5. FTC_4nt34ter_
  6. CTF(R3indeeR}
  7. FTC{PenGuin}
  8. {Pl4typuS}FTC
  9. FLAGTHECAPTURE
  10. FTC{{EL3PHant}}
Tip: Check the flag format for this CTF.

Challenge 2: Cryptography.
Quick! Decode this message: RlRDe0I0c2VfNjRfZ2VuaXVzfQ==.
 
Challenge 3: Web.
There's a flag hiding in the HTML code here. Can you spot it?
Tip: Press Shift-Control-I to open your browser's developer tools. This will show the HTML code on this page.

Challenge 4: Programming.
This python program contains a flag, but you need to enter the secret password first.


if input('What is the password? ') == 'FLAGtheCAPTURE':
    output = ''
    for i in [70, 84, 67, 123, 83, 78, 52, 75, 69, 83, 125]:
        output+=chr(i)
    print('The Flag is:\n'+output)
else:
    print('ERROR. No flag for you.')


Tip: Play with the code in a python interpreter, like this one:  https://www.programiz.com/python-programming/online-compiler/.

Challenge 5: OSINT (Open Source Intelligence).
The final flag is hidden on another page of this website (flagthecapture.blogspot.com/). Explore every link. 
Tip: Use menu bar and the contents page to explore websites quickly.

Found all five flags? Click the button to see if you're a CTF champion!

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