ctf write-up tagged posts

decoding an incomplete QRCode – Intigriti Hacking Challenge at bruCON

This year I was at bruCon in Ghent, BE. I usually either go to interesting talks or spend the conferences in challenges just like I did in Defcon back in 2017.

So during bruCON I stumbled upon this challenge with QR-code that says “first one to scan this gets 100€”; in my head I thought pff this is easy and I will probably not be the first one to scan this. So I popped my phone and scanned. Nothing happened. Then I was like oh wait .. a huge piece of this qr-code is missing.

So the first thing I thought of is to mark the squares randomly because I thought it must be redundant or error correction squars. Remember at this point I know nothing about qr-codes...

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