tl;dr

• Challenge is a VM implemented over signals and ptrace
• Reverse Instruction types and implementation
• Use gdb scripting to find the executed code and get the pseudo VM code
• Reverse the VM functionality (Hill cipher) for flag and profit

tl;dr

• You need to pass 999 levels to get the flag.
• Each of the levels involves multiple checks on input characters.
• Each check happens in seperate functions which are decrypted during runtime.
• Extract function order and arguments.
• Automate finding input for each check.