reversehard

KrackM3

knightctf

Task: Find the correct flag for a stripped 524MB ELF crackme with S-box substitution and PRNG-based verification. Solution: Use Unicorn CPU emulator to emulate the verification function, hook at the check7 OR instruction to capture r13 values, brute-force each flag character position to find bytes that make the check7 accumulator zero.

$ ls tags/ techniques/
cpu_emulationhook_based_analysischaracter_bruteforceaccumulator_analysis

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