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GUARDED INPUT

Windows PE executable disassembly, analyzing decryption loop instructions to identify XOR parameters.

Tools Used

pefilecapstonePython

Overview

A 64-bit Windows command-line binary checks user inputs and validates flags.

Reconnaissance

Using Capstone to disassemble the .text section, we locate key bytes moved to memory in main functions.

Exploitation Strategy

The inputs are XORed with 0x5b before verification. We decrypt the expected key bytes to pass input check constraints and recover the flag.

Solution Code

key_bytes = [0x1e, 0x0f, 0x1b, 0x7a, 0x2d, 0x3c, 0x20, 0x2b, 0x2b, 0x3c, 0x20, 0x2d, 0x7c]
print(''.join([chr(b ^ 0x5b) for b in key_bytes]))

Flag

Kaal{4r3_y0u_cr4k3_k44l_ch4kr4}