Medium Live

CTF 6502

40 points

24 Solves

Reverse Engineering


heinandre ctflearn++ badge

Community Rating: 4.67 / 5

Welcome to the CTF 6502 challenge!

In this CTF challenge, the MOS 6502 has returned. This time it doesn't power a home video game console or computer system like the Nintendo Entertainment System or the Commodore 64.

This time it's hiding our flag! Let's travel back in time to the beginning of the home computer revolution, whip out our programming manual and get our hands dirty with some good old 6502-assembly.

Implement the missing opcode in the OPCODE_0x49-method and fix the machine code in the program-variable.

When you're done you should be able to read the flag in the memory dump at memory address 0x0040.

Good luck, I'll see you in the future!

(The Program.cs-file is attached. Run it any way you prefer. Or use .NET Fiddle to run it in your browser here:

First 10 Solvers

Rank Username
1 heinandre ctflearn++ badge
2 Ntoskrnl
3 0mr1
4 PleSo ctflearn++ badge
5 Exolon
Rank Username
6 bobo1239
7 oter
8 digital_turtle
9 ebouteillon
10 linncappu

  • intelagent moderator badge ctflearn++ badge


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