reversehard

VMM - Virtual Machine Monster

hackerlab

Task: UPX-packed PE64 with corrupted magic header implements a custom 24-opcode stack VM that validates input through ROT13 + ADD/XOR/SUB chain. Solution: emulate NRV2B decompressor with Unicorn Engine to unpack, reverse VM opcodes, extract transform constants, invert the chain to recover the flag.

$ ls tags/ techniques/

pe64 xor obfuscation rot13 mingw bytecode caesar_cipher upx windows_pe anti_debug custom_vm stack_machine anti_unpack nrv2b prng_noise

vm_bytecode_analysisupx_header_patchingunicorn_emulation_unpackingnrv2b_decompressor_emulationvm_opcode_recoverytransform_chain_inversionrot13_reversaladd_xor_sub_chain_bruteforce

Analysis

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$ python3 exploit.py --target 192.168.1.1 --port 8080
[*] Connecting to target...
[+] Shell obtained!

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