vmemu/src/main.cpp

#include "unpacker.hpp"
#include "vmemu_t.hpp"

#include <cli-parser.hpp>
#include <fstream>
#include <iostream>
#include <xtils.hpp>

int __cdecl main( int argc, const char *argv[] )
{
    argparse::argument_parser_t parser( "VMEmu", "VMProtect 2 VM Handler Emulator" );
    parser.add_argument().name( "--vmentry" ).description( "relative virtual address to a vm entry..." );
    parser.add_argument().name( "--bin" ).description( "path to unpacked virtualized binary..." );
    parser.add_argument().name( "--out" ).description( "output file name..." );
    parser.add_argument().name( "--unpack" ).description( "unpack a vmp2 binary..." );
    parser.add_argument()
        .name( "--locateconst" )
        .description( "scan all vm enters for a specific constant value...\n" );

    parser.enable_help();
    auto result = parser.parse( argc, argv );

    if ( result )
    {
        std::printf( "[!] error parsing commandline arguments... reason = %s\n", result.what().c_str() );
        return -1;
    }

    if ( parser.exists( "help" ) )
    {
        parser.print_help();
        return 0;
    }

    auto umtils = xtils::um_t::get_instance();

    if ( !parser.exists( "unpack" ) && parser.exists( "vmentry" ) && parser.exists( "bin" ) && parser.exists( "out" ) )
    {
        const auto module_base = reinterpret_cast< std::uintptr_t >(
            LoadLibraryExA( parser.get< std::string >( "bin" ).c_str(), NULL, DONT_RESOLVE_DLL_REFERENCES ) );

        if ( !module_base )
        {
            std::printf( "[!] failed to open binary file...\n" );
            return -1;
        }

        const auto vm_entry_rva = std::strtoull( parser.get< std::string >( "vmentry" ).c_str(), nullptr, 16 );
        const auto image_base = umtils->image_base( parser.get< std::string >( "bin" ).c_str() );
        const auto image_size = NT_HEADER( module_base )->OptionalHeader.SizeOfImage;

        std::printf( "> image base = %p, image size = %p, module base = %p\n", image_base, image_size, module_base );

        if ( !image_base || !image_size || !module_base )
        {
            std::printf( "[!] failed to open binary on disk...\n" );
            return -1;
        }

        std::vector< vm::instrs::code_block_t > code_blocks;
        vm::ctx_t vmctx( module_base, image_base, image_size, vm_entry_rva );

        if ( !vmctx.init() )
        {
            std::printf( "[!] failed to init vmctx... this can be for many reasons..."
                         " try validating your vm entry rva... make sure the binary is unpacked and is"
                         "protected with VMProtect 2...\n" );
            return -1;
        }

        vm::emu_t emu( &vmctx );

        if ( !emu.init() )
        {
            std::printf( "[!] failed to init emulator...\n" );
            return -1;
        }

        if ( !emu.get_trace( code_blocks ) )
        {
            std::printf( "[!] something failed during tracing, review the console for more information...\n" );
            return -1;
        }

        std::printf( "> number of blocks = %d\n", code_blocks.size() );

        for ( auto &code_block : code_blocks )
        {
            std::printf( "> code block starts at = %p\n", code_block.vip_begin );
            std::printf( "> number of virtual instructions = %d\n", code_block.vinstrs.size() );
            std::printf( "> does this code block have a jcc? %s\n", code_block.jcc.has_jcc ? "yes" : "no" );

            if ( code_block.jcc.has_jcc )
                std::printf( "> branch 1 = %p, branch 2 = %p\n", code_block.jcc.block_addr[ 0 ],
                             code_block.jcc.block_addr[ 1 ] );
        }

        std::printf( "> serializing results....\n" );
        vmp2::v3::file_header file_header;
        file_header.magic = VMP_MAGIC;
        file_header.epoch_time = std::time( nullptr );
        file_header.version = vmp2::version_t::v3;
        file_header.module_base = module_base;
        file_header.image_base = image_base;
        file_header.vm_entry_rva = vm_entry_rva;
        file_header.module_offset = sizeof file_header;
        file_header.module_size = image_size;
        file_header.code_block_offset = image_size + sizeof file_header;
        file_header.code_block_count = code_blocks.size();

        std::ofstream output( parser.get< std::string >( "out" ), std::ios::binary );
        output.write( reinterpret_cast< const char * >( &file_header ), sizeof file_header );
        output.write( reinterpret_cast< const char * >( module_base ), image_size );

        for ( const auto &code_block : code_blocks )
        {
            const auto _code_block_size =
                ( code_block.vinstrs.size() * sizeof vm::instrs::virt_instr_t ) + sizeof vmp2::v3::code_block_t;

            vmp2::v3::code_block_t *_code_block =
                reinterpret_cast< vmp2::v3::code_block_t * >( malloc( _code_block_size ) );

            _code_block->vip_begin = code_block.vip_begin;
            _code_block->jcc = code_block.jcc;
            _code_block->next_block_offset = _code_block_size;
            _code_block->vinstr_count = code_block.vinstrs.size();

            for ( auto idx = 0u; idx < code_block.vinstrs.size(); ++idx )
                _code_block->vinstr[ idx ] = code_block.vinstrs[ idx ];

            output.write( reinterpret_cast< const char * >( _code_block ), _code_block_size );
        }

        output.close();
    }
    else if ( parser.exists( "unpack" ) && parser.exists( "bin" ) && parser.exists( "out" ) )
    {
        std::vector< std::uint8_t > packed_bin, unpacked_bin;
        if ( !umtils->open_binary_file( parser.get< std::string >( "unpack" ), packed_bin ) )
        {
            std::printf( "> failed to read bin off disk...\n" );
            return -1;
        }

        engine::unpack_t unpacker( packed_bin );

        if ( !unpacker.init() )
        {
            std::printf( "> failed to init unpacker...\n" );
            return -1;
        }

        if ( !unpacker.unpack( unpacked_bin ) )
        {
            std::printf( "> failed to unpack binary... refer to log above...\n" );
            return -1;
        }

        std::printf( "> writing result to = %s\n", parser.get< std::string >( "out" ).c_str() );
        std::ofstream output( parser.get< std::string >( "out" ), std::ios::binary );
        output.write( reinterpret_cast< char * >( unpacked_bin.data() ), unpacked_bin.size() );
        output.close();
    }
    else if ( parser.exists( "bin" ) && parser.exists( "locateconst" ) )
    {
        std::vector< vm::instrs::code_block_t > code_blocks;
        const auto module_base = reinterpret_cast< std::uintptr_t >(
            LoadLibraryExA( parser.get< std::string >( "bin" ).c_str(), NULL, DONT_RESOLVE_DLL_REFERENCES ) );

        const auto const_val = std::strtoull( parser.get< std::string >( "locateconst" ).c_str(), nullptr, 16 );
        const auto image_base = umtils->image_base( parser.get< std::string >( "bin" ).c_str() );
        const auto image_size = NT_HEADER( module_base )->OptionalHeader.SizeOfImage;

        auto vm_handler_tables = vm::locate::all_handler_tables( module_base );
        auto vm_enters = vm::locate::all_vm_enters( module_base, vm_handler_tables );

        std::printf( "> number of vm enters = %d\n", vm_enters.size() );
        if ( std::find_if( vm_enters.begin() + 1, vm_enters.end(),
                           [ & ]( const std::pair< std::uint32_t, std::uint32_t > &vm_enter_data ) -> bool {
                               return vm_enter_data.second == vm_enters[ 0 ].second;
                           } ) != vm_enters.end() )
        {
            std::printf( "> optimizations can be done.\n" );
            std::getchar();
        }

        for ( const auto &[ vm_enter_offset, encrypted_rva ] : vm_enters )
        {
            std::printf( "> emulating vm enter at rva = 0x%x\n", vm_enter_offset );
            vm::ctx_t vm_ctx( module_base, image_base, image_size, vm_enter_offset );

            if ( !vm_ctx.init() )
            {
                std::printf( "[!] failed to init vmctx... this can be for many reasons..."
                             " try validating your vm entry rva... make sure the binary is unpacked and is"
                             "protected with VMProtect 2...\n" );
                return -1;
            }

            vm::emu_t emu( &vm_ctx );

            if ( !emu.init() )
            {
                std::printf( "[!] failed to init emulator...\n" );
                return -1;
            }

            std::vector< vm::instrs::code_block_t > new_code_blocks;

            if ( !emu.get_trace( new_code_blocks ) )
            {
                std::printf( "[!] something failed during tracing, review the console for more information...\n" );
                continue;
            }

            std::printf( "> number of blocks = %d\n", new_code_blocks.size() );

            for ( auto &code_block : new_code_blocks )
            {
                for ( const auto &vinstr : code_block.vinstrs )
                {
                    if ( vinstr.operand.has_imm && vinstr.operand.imm.u == const_val )
                    {
                        std::printf( "> found constant in vm enter at = 0x%x\n", vm_enter_offset );
                        std::getchar();
                    }
                }
            }

            code_blocks.insert( code_blocks.end(), new_code_blocks.begin(), new_code_blocks.end() );
        }
    }
}