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gogo9211gogo9211
committedSep 3, 2024
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‎roblox_decryptor.sln

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Microsoft Visual Studio Solution File, Format Version 12.00
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# Visual Studio Version 16
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VisualStudioVersion = 16.0.34601.136
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MinimumVisualStudioVersion = 10.0.40219.1
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Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "roblox_decryptor", "roblox_decryptor\roblox_decryptor.vcxproj", "{95843837-C21A-4CDC-BC04-28271ABD09A6}"
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EndProject
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Global
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GlobalSection(SolutionConfigurationPlatforms) = preSolution
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Debug|x64 = Debug|x64
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Debug|x86 = Debug|x86
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Release|x64 = Release|x64
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Release|x86 = Release|x86
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EndGlobalSection
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GlobalSection(ProjectConfigurationPlatforms) = postSolution
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Debug|x64.ActiveCfg = Debug|x64
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Debug|x64.Build.0 = Debug|x64
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Debug|x86.ActiveCfg = Debug|Win32
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Debug|x86.Build.0 = Debug|Win32
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Release|x64.ActiveCfg = Release|x64
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Release|x64.Build.0 = Release|x64
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Release|x86.ActiveCfg = Release|Win32
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{95843837-C21A-4CDC-BC04-28271ABD09A6}.Release|x86.Build.0 = Release|Win32
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EndGlobalSection
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GlobalSection(SolutionProperties) = preSolution
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HideSolutionNode = FALSE
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EndGlobalSection
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GlobalSection(ExtensibilityGlobals) = postSolution
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SolutionGuid = {FF4F996F-CFDD-4C90-9869-5A658DD12C93}
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EndGlobalSection
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EndGlobal

‎roblox_decryptor/decryptor/decryptor.cpp

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#include "decryptor.hpp"
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#include "utils/memory.hpp"
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#include "utils/pe.hpp"
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#include <Windows.h>
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#include <vendor/chacha20/chacha20.hpp>
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namespace decryptor
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{
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code_decryptor::code_decryptor(const std::filesystem::path& hyperion, const std::filesystem::path& roblox, const std::string& out_filename) : page_info_base{ 0 }
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{
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// Loading the module directly so we can work with memory mapped offsets
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hyperion_handle = LoadLibraryExA(hyperion.string().c_str(), NULL, DONT_RESOLVE_DLL_REFERENCES);
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roblox_handle = LoadLibraryExA(roblox.string().c_str(), NULL, DONT_RESOLVE_DLL_REFERENCES);
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if (!roblox_handle || !hyperion_handle)
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return;
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utils::pe roblox_image{ get_base_from_handle(roblox_handle) };
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utils::pe hyperion_image{ get_base_from_handle(hyperion_handle) };
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const auto roblox_code = roblox_image.get_section(".text");
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const auto hyperion_code = hyperion_image.get_section(".byfron");
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DWORD old;
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VirtualProtect(reinterpret_cast<LPVOID>(roblox_code.base), roblox_code.size, PAGE_READWRITE, &old);
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// Attempt to automatically locate the page info array
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constexpr std::array<std::uint8_t, 6> constant_sig = { 0x10, 0x27, 0x00, 0x00, 0xCC, 0x29 };
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constexpr std::array<std::uint8_t, 3> lea_sig = { 0x04, 0xCC, 0x8D };
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const auto constant_mov = utils::signature_scan(hyperion_code.base, hyperion_code.size, constant_sig);
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if (!constant_mov)
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return;
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auto page_info_lea = utils::signature_scan(constant_mov, 0x100, lea_sig);
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if (!page_info_lea)
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return;
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// Plus one because we include the end of the shl reg, 4 instruction
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page_info_lea += 1;
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const auto dest = page_info_lea + *reinterpret_cast<std::int32_t*>(page_info_lea + 3) + 7;
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page_info_base = dest;
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std::ifstream src{ roblox, std::ios::binary };
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out_file = std::ofstream{ out_filename, std::ios::binary };
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out_file << src.rdbuf();
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src.close();
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}
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code_decryptor::~code_decryptor()
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{
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if (hyperion_handle)
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FreeLibrary(static_cast<HMODULE>(hyperion_handle));
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if (roblox_handle)
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FreeLibrary(static_cast<HMODULE>(roblox_handle));
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}
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bool code_decryptor::is_initialized() const
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{
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return page_info_base != 0;
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}
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void code_decryptor::decrypt()
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{
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utils::pe roblox_image{ get_base_from_handle(roblox_handle) };
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utils::pe hyperion_image{ get_base_from_handle(hyperion_handle) };
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const auto roblox_code = roblox_image.get_section(".text");
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const auto hyperion_code = hyperion_image.get_section(".byfron");
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for (auto target_page = roblox_code.base; target_page < roblox_code.base + roblox_code.size; target_page += 0x1000)
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{
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const auto target_page_number = (target_page - roblox_image.get_image_base()) / 0x1000;
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const auto target_page_info_base = page_info_base + (target_page_number % 10000) * 0x10;
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const auto page_info = *reinterpret_cast<std::uintptr_t*>(target_page_info_base);
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const auto page_size = *reinterpret_cast<std::uint32_t*>(target_page_info_base + 0x8);
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std::array<std::uint8_t, 32> key{};
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std::memcpy(key.data(), reinterpret_cast<void*>(page_info), page_size);
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chacha20_context ctx;
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chacha20_init_context(&ctx, key.data(), 0);
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chacha20_xor(&ctx, reinterpret_cast<uint8_t*>(target_page), 0x1000);
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}
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// Seek to the first section after the PE headers, assuming it should be code
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out_file.seekp(0x600);
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out_file.write(reinterpret_cast<char*>(roblox_code.base), roblox_code.size);
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out_file.flush();
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}
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std::uintptr_t code_decryptor::get_base_from_handle(void* handle) const
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{
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return reinterpret_cast<std::uintptr_t>(handle);
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}
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}

‎roblox_decryptor/decryptor/decryptor.hpp

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#pragma once
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#include <cstdint>
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#include <string>
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#include <filesystem>
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#include <fstream>
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#include <array>
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namespace decryptor
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{
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class code_decryptor
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{
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public:
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code_decryptor(const std::filesystem::path& hyperion, const std::filesystem::path& roblox, const std::string& out_filename);
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~code_decryptor();
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void decrypt();
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bool is_initialized() const;
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private:
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std::uintptr_t get_base_from_handle(void* handle) const;
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private:
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void* hyperion_handle;
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void* roblox_handle;
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std::uintptr_t page_info_base;
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std::ofstream out_file;
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};
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}

‎roblox_decryptor/roblox_decryptor.cpp

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#include <iostream>
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#include "decryptor/decryptor.hpp"
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using namespace decryptor;
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int main()
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{
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std::printf("Starting decryptor\n");
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code_decryptor static_decryptor{ "RobloxPlayerBeta.dll", "RobloxPlayerBeta.exe", "decrypted.bin" };
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if (!static_decryptor.is_initialized())
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{
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std::printf("Decryptor failed to initialize\n");
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std::cin.get();
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return 1;
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}
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static_decryptor.decrypt();
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std::printf("Decryptor successfully finished\n");
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std::cin.get();
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}

‎roblox_decryptor/roblox_decryptor.vcxproj

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