Clear it in 3 steps
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Start the environment
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Investigate the target
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Submit the flag
Repair firmware.bin by writing KINO at bytes 0-3 and the little-endian CRC32 of bytes 12+ at bytes 8-11. Submit the repaired file to challenge.py to print the startup-injected FLAG.
Modify the file with bytearray
Use zlib.crc32(data[12:])
Store it using to_bytes(4, 'little')