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vmemu
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in the middle of something adding branch detection code

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merge-requests/4/head
_xeroxz 3 years ago
parent 8842aad46f
commit 5fd0d89b4c
3 changed files with 41 additions and 96 deletions
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2
dependencies/vmprofiler vendored

@ -1 +1 @@
Subproject commit e58c23c40e13528f5d9b84feb7e23b62a886ed5a
Subproject commit ffd45ecb8a6a6a5d066a9b5e96c878ed9e09e243

88
src/vmemu_t.cpp
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@ -3,47 +3,19 @@
namespace vm
{
emu_t::emu_t( std::uint32_t vm_entry_rva, std::uintptr_t image_base, std::uintptr_t module_base )
: module_base( module_base ), image_base( image_base ), vm_entry_rva( vm_entry_rva ),
vm_handler_table( nullptr ), uc( nullptr ), trace_entries( nullptr )
: module_base( module_base ), image_base( image_base ), vm_entry_rva( vm_entry_rva ), uc( nullptr ),
code_blocks( nullptr ), vmctx( new vm::ctx_t( module_base, image_base, vm_entry_rva ) )
{
}
bool emu_t::init()
{
// vmprofiler init stuff...
if ( !vm::util::flatten( vm_entry, vm_entry_rva + module_base ) )
{
std::printf( "[!] failed to get vm entry...\n" );
return false;
}
vm::util::deobfuscate( vm_entry );
vm::util::print( vm_entry );
if ( !( vm_handler_table = vm::handler::table::get( vm_entry ) ) )
{
std::printf( "[!] failed to get vm handler table...\n" );
return false;
}
std::printf( "> vm handler table = 0x%p\n", vm_handler_table );
if ( !vm::handler::get_all( module_base, image_base, vm_entry, vm_handler_table, vm_handlers ) )
{
std::printf( "[!] failed to get all vm handlers...\n" );
return false;
}
std::printf( "> got all vm handlers...\n" );
for ( const vm::handler::handler_t &vm_handler : vm_handlers )
std::printf( ">>> handler addr = 0x%p\n", vm_handler.address );
// unicorn init stuff...
const auto image_size = NT_HEADER( module_base )->OptionalHeader.SizeOfImage;
uc_err err;
std::uintptr_t stack_base = 0x1000000;
std::uintptr_t stack_addr = ( stack_base + ( 0x1000 * 20 ) ) - 0x6000;
const auto rip = module_base + vm_entry_rva;
const auto image_size = NT_HEADER( module_base )->OptionalHeader.SizeOfImage;
uc_err err;
if ( ( err = uc_open( UC_ARCH_X86, UC_MODE_64, &uc ) ) )
{
std::printf( "failed on uc_mem_map() with error returned %u: %s\n", err, uc_strerror( err ) );
@ -72,7 +44,7 @@ namespace vm
return false;
}
if ( ( err = uc_reg_write( uc, UC_X86_REG_RIP, &vm_entry ) ) )
if ( ( err = uc_reg_write( uc, UC_X86_REG_RIP, &rip ) ) )
{
std::printf( "failed on uc_reg_write() with error returned %u: %s\n", err, uc_strerror( err ) );
@ -108,12 +80,14 @@ namespace vm
{
if ( uc )
uc_close( uc );
delete vmctx;
}
bool emu_t::get_trace( std::vector< vmp2::v2::entry_t > &entries )
bool emu_t::get_trace( std::vector< vm::instrs::code_block_t > &entries )
{
// hook_code will fill this vector up with values...
trace_entries = &entries;
code_blocks = &entries;
uc_err err;
if ( ( err = uc_emu_start( uc, vm_entry_rva + module_base, NULL, NULL, NULL ) ) )
@ -166,17 +140,15 @@ namespace vm
std::printf( ">>> Tracing instruction at 0x%p, instruction size = 0x%x\n", address, size );
// grab JMP RDX/RCX <-- this register...
static const auto jmp_reg = obj->vm_entry[ obj->vm_entry.size() ].instr.operands[ 0 ].reg.value;
static const auto jmp_reg = obj->vmctx->vm_entry[ obj->vmctx->vm_entry.size() ].instr.operands[ 0 ].reg.value;
static ZydisDecoder decoder;
static std::once_flag once;
static ZydisDecodedInstruction instr;
static std::uintptr_t reg_val = 0u;
// init zydis decoder just a single time...
std::call_once( once, [ & ]() -> void {
// init zydis decoder only a single time...
if ( static std::atomic< bool > once = true; once.exchange( false ) )
ZydisDecoderInit( &decoder, ZYDIS_MACHINE_MODE_LONG_64, ZYDIS_ADDRESS_WIDTH_64 );
} );
if ( ZYAN_SUCCESS(
ZydisDecoderDecodeBuffer( &decoder, reinterpret_cast< void * >( address ), size, &instr ) ) &&
@ -185,6 +157,7 @@ namespace vm
{
uc_err err;
vmp2::v2::entry_t new_entry;
std::optional< vm::instrs::virt_instr_t > virt_instr;
vm::handler::profile_t *vm_handler_profile = nullptr;
switch ( jmp_reg )
@ -206,8 +179,8 @@ namespace vm
return vm_handler.address == reg_val;
};
if ( std::find_if( obj->vm_handlers.begin(), obj->vm_handlers.end(), vm_handler_check ) ==
obj->vm_handlers.end() )
if ( std::find_if( obj->vmctx->vm_handlers.begin(), obj->vmctx->vm_handlers.end(), vm_handler_check ) ==
obj->vmctx->vm_handlers.end() )
return;
if ( ( err = obj->create_entry( &new_entry ) ) )
@ -217,21 +190,34 @@ namespace vm
exit( 0 );
}
if ( ( vm_handler_profile = obj->vm_handlers[ new_entry.handler_idx ].profile ) &&
vm_handler_profile->mnemonic == vm::handler::mnemonic_t::JMP )
// the first virtual instruction we are going to create the first code_block_t...
if ( static std::atomic< bool > once = true; once.exchange( false ) )
if ( obj->code_blocks->empty() )
obj->code_blocks->push_back( vm::instrs::code_block_t{ new_entry.vip } );
if ( virt_instr = vm::instrs::get( *obj->vmctx, new_entry ); !virt_instr.has_value() )
{
std::printf( "> stopping at virtual jump instruction...\n" );
std::getchar();
std::printf( "[!] failed to create vm::instrs::virt_instr_t...\n" );
exit( 0 );
}
obj->trace_entries->push_back( new_entry );
obj->code_blocks->back().vinstrs.push_back( virt_instr.value() );
// if there is a virtual JMP instruction then we need to create a new code_block_t...
if ( ( vm_handler_profile = obj->vmctx->vm_handlers[ new_entry.handler_idx ].profile ) &&
vm_handler_profile->mnemonic == vm::handler::mnemonic_t::JMP )
{
const auto code_block_address =
vm::instrs::code_block_addr( *obj->vmctx, new_entry, obj->image_base, obj->module_base );
// set the next code block up...
obj->code_blocks->push_back( vm::instrs::code_block_t{ code_block_address } );
}
}
else if ( instr.mnemonic == ZYDIS_MNEMONIC_RET ) // finish tracing...
{
uc_emu_stop( uc );
std::printf( "> stopping at vmexit instruction...\n" );
std::getchar();
}
}

47
src/vmemu_t.hpp
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@ -11,45 +11,6 @@
namespace vm
{
struct virt_instr_t
{
vm::handler::mnemonic_t mnemonic_t;
std::uint8_t opcode; // aka vm handler idx...
struct
{
bool has_imm;
struct
{
std::uint8_t imm_size; // size in bits...
union
{
std::int64_t s;
std::uint64_t u;
};
} imm;
} operand;
};
enum class jcc_type
{
none,
branching,
absolute
};
struct code_block_t
{
struct
{
bool has_jcc;
jcc_type type;
std::uint32_t branch_rva[ 2 ];
} jcc;
std::vector< virt_instr_t > vinstrs;
};
class emu_t
{
using callback_t = std::function< void( uc_engine *, uint64_t, uint32_t, void * ) >;
@ -59,7 +20,7 @@ namespace vm
~emu_t();
bool init();
bool get_trace( std::vector< vmp2::v2::entry_t > &entries );
bool get_trace( std::vector< vm::instrs::code_block_t > &entries );
private:
uc_err create_entry( vmp2::v2::entry_t *entry );
@ -73,9 +34,7 @@ namespace vm
std::uintptr_t image_base, module_base;
std::uint32_t vm_entry_rva;
zydis_routine_t vm_entry;
std::uintptr_t *vm_handler_table;
std::vector< vm::handler::handler_t > vm_handlers;
std::vector< vmp2::v2::entry_t > *trace_entries;
vm::ctx_t* vmctx;
std::vector< vm::instrs::code_block_t > *code_blocks;
};
} // namespace vm
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