HackTheBox Mini Line Writeup

Explore the basics of cybersecurity in the Mini Line Challenge on Hack The Box. This easy-level Challenge introduces encryption reversal and file handling concepts in a clear and accessible way, perfect for beginners.

arm-none-eabi-binutils

arm-none-eabi-objcopy -I ihex -O binary firmware.hex firmware
arm-none-eabi-objdump -D -b binary -m arm firmware

Decompile firmware

first = [0x52, 0x4e, 0x58, 0x61, 0x78, 0x2e, 0x68, 0x29, 0x45, 0x77, 0x29, 0x6e, 0x2e, 0x76, 0x69, 0x45]
second = [0x1a, 0x96, 0x14, 0xcc, 0xbe, 0x98, 0xae, 0xcc, 0x14, 0x12, 0xba, 0xbe, 0x10, 0x30, 0x30, 0x30, 0x88]

def extract_flag(first, second):
    decoded_first = ''.join(chr(i ^ 0x1A) for i in first)
    decoded_second = ''.join(chr((j >> 1) ^ 0x39) for j in second)
    return decoded_first + decoded_second

print("Decoded Flag:", extract_flag(first, second))

Summary

The Mini Line Challenge explores ARM firmware reverse engineering, utilizing disassembly and bitwise operations to decode encrypted data transmitted via SPI. The challenge highlights hardware security concepts, encryption reversal, and the fundamentals of analyzing microcontroller firmware.