cube

rev_kids20

Task: 32-bit x86 ELF builds the flag inside a nested heap structure (linked 16-byte cells) and only prints hints, never the flag; each diagonal cell stores table[idx] XOR (idx%255). Solution: statically reconstruct the cell indices and decode; key insight is that the compiler magic-number division (0x80808081 + sar 7 + shl8/sub) computes idx%255, NOT idx%257 — the wrong modulus only corrupts the row-3 tail, masking the bug behind a correct 'flag_is_' prefix.