Author:
kamil123

Language:
C/C++

Upload:
2026-09-28 19:13

Platform:
Windows

Difficulty:
6.0

Quality:
4.0

Arch:
x86-64

Downloads:
22

Size:
24.00 KB

Writeups:
0

Comments:
1

Description

A hard custom-VM crackme: the password is validated inside a small custom register virtual machine. The VM bytecode is encrypted, uses a permuted opcode map, and the opcode stream is additionally keyed at runtime, so a static dump alone is not enough; the validation program contains opaque predicates, decoy blocks and junk instructions. Goal: find the password (a fixed string - no keygen). How to run: run crackme.exe (Windows console application) and type a password when prompted. The program prints a success message when the password is accepted. Notes: - Anti-debugging is part of the challenge: when a debugger is present, every password is rejected (including the correct one). Under a debugger the process may also keep the debugger waiting on exit - that is intentional. - Hiding plugins are detected: if ScyllaHide (or a similar plugin's hook library) is active, the program notices the injected module and/or the inline hooks on ntdll/kernel32/user32 entry points and terminates itself immediately. - The program verifies its own code against the on-disk image, so software breakpoints or patches on the validation functions are detected and cause silent rejection. A background watchdog re-checks continuously. - Fully solvable with static analysis. No packing, no network access, statically linked, no dependencies. Good luck!

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