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fixed some issues with getting operand decryption transforms

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merge-requests/4/head
_xeroxz 3 years ago
parent 8d564257b2
commit 0115f85798
3 changed files with 58 additions and 66 deletions
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9
include/transform.hpp
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@ -136,19 +136,24 @@ namespace vm
template < class T > inline const auto _dec = []( T a, T b ) -> T { return a - 1; };
template < class T >
inline std::map< ZydisMnemonic, transform_t< T > > transforms = {
inline std::map< zydis_mnemonic_t, transform_t< T > > transforms = {
{ ZYDIS_MNEMONIC_ADD, _add< T > }, { ZYDIS_MNEMONIC_XOR, _xor< T > }, { ZYDIS_MNEMONIC_BSWAP, _bswap< T > },
{ ZYDIS_MNEMONIC_SUB, _sub< T > }, { ZYDIS_MNEMONIC_NEG, _neg< T > }, { ZYDIS_MNEMONIC_NOT, _not< T > },
{ ZYDIS_MNEMONIC_ROR, _ror< T > }, { ZYDIS_MNEMONIC_ROL, _rol< T > }, { ZYDIS_MNEMONIC_INC, _inc< T > },
{ ZYDIS_MNEMONIC_DEC, _dec< T > } };
inline std::map< ZydisMnemonic, ZydisMnemonic > inverse = {
inline std::map< zydis_mnemonic_t, zydis_mnemonic_t > inverse = {
{ ZYDIS_MNEMONIC_ADD, ZYDIS_MNEMONIC_SUB }, { ZYDIS_MNEMONIC_XOR, ZYDIS_MNEMONIC_XOR },
{ ZYDIS_MNEMONIC_BSWAP, ZYDIS_MNEMONIC_BSWAP }, { ZYDIS_MNEMONIC_SUB, ZYDIS_MNEMONIC_ADD },
{ ZYDIS_MNEMONIC_NEG, ZYDIS_MNEMONIC_NEG }, { ZYDIS_MNEMONIC_NOT, ZYDIS_MNEMONIC_NOT },
{ ZYDIS_MNEMONIC_ROR, ZYDIS_MNEMONIC_ROL }, { ZYDIS_MNEMONIC_ROL, ZYDIS_MNEMONIC_ROR },
{ ZYDIS_MNEMONIC_INC, ZYDIS_MNEMONIC_DEC }, { ZYDIS_MNEMONIC_DEC, ZYDIS_MNEMONIC_INC } };
inline bool valid( zydis_mnemonic_t op )
{
return transforms< std::uint8_t >.find( op ) != transforms< std::uint8_t >.end();
}
inline void inverse_transforms( transform::map_t &transforms, transform::map_t &inverse )
{
inverse[ transform::type::generic0 ] = transforms[ transform::type::generic0 ];

1
include/vmutils.h
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@ -12,6 +12,7 @@ using u128 = __m128;
using zydis_decoded_instr_t = ZydisDecodedInstruction;
using zydis_register_t = ZydisRegister;
using zydis_mnemonic_t = ZydisMnemonic;
struct zydis_instr_t
{

114
src/vmhandler.cpp
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@ -152,16 +152,14 @@ namespace vm
auto imm_fetch =
std::find_if( vm_handler.begin(), vm_handler.end(), []( const zydis_instr_t &instr_data ) -> bool {
// mov/movsx/movzx rax/eax/ax/al, [rsi]
if ( instr_data.instr.operand_count > 1 &&
( instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOV ||
instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOVSX ||
instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOVZX ) &&
instr_data.instr.operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
util::reg::to64( instr_data.instr.operands[ 0 ].reg.value ) == ZYDIS_REGISTER_RAX &&
instr_data.instr.operands[ 1 ].type == ZYDIS_OPERAND_TYPE_MEMORY &&
instr_data.instr.operands[ 1 ].mem.base == ZYDIS_REGISTER_RSI )
return true;
return false;
return ( instr_data.instr.operand_count > 1 &&
( instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOV ||
instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOVSX ||
instr_data.instr.mnemonic == ZYDIS_MNEMONIC_MOVZX ) &&
instr_data.instr.operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
util::reg::to64( instr_data.instr.operands[ 0 ].reg.value ) == ZYDIS_REGISTER_RAX &&
instr_data.instr.operands[ 1 ].type == ZYDIS_OPERAND_TYPE_MEMORY &&
instr_data.instr.operands[ 1 ].mem.base == ZYDIS_REGISTER_RSI );
} );
if ( imm_fetch == vm_handler.end() )
@ -169,52 +167,51 @@ namespace vm
// this finds the first transformation which looks like:
// transform rax, rbx <--- note these registers can be smaller so we to64 them...
auto key_transform =
auto transform_instr =
std::find_if( imm_fetch, vm_handler.end(), []( const zydis_instr_t &instr_data ) -> bool {
if ( util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX ) &&
util::reg::compare( instr_data.instr.operands[ 1 ].reg.value, ZYDIS_REGISTER_RBX ) )
return true;
return false;
return vm::transform::valid( instr_data.instr.mnemonic ) &&
instr_data.instr.operands[ 0 ].actions & ZYDIS_OPERAND_ACTION_WRITE &&
util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX ) &&
util::reg::compare( instr_data.instr.operands[ 1 ].reg.value, ZYDIS_REGISTER_RBX );
} );
if ( key_transform == vm_handler.end() )
if ( transform_instr == vm_handler.end() )
return false;
// look for a primer/instruction that alters RAX prior to the 5 transformations...
auto generic0 = std::find_if( imm_fetch + 1, key_transform, []( const zydis_instr_t &instr_data ) -> bool {
return util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX ) &&
auto generic0 = std::find_if( imm_fetch, transform_instr, []( const zydis_instr_t &instr_data ) -> bool {
return vm::transform::valid( instr_data.instr.mnemonic ) &&
instr_data.instr.operands[ 0 ].actions & ZYDIS_OPERAND_ACTION_WRITE &&
util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX ) &&
!util::reg::compare( instr_data.instr.operands[ 1 ].reg.value, ZYDIS_REGISTER_RBX );
} );
zydis_decoded_instr_t nogeneric0;
nogeneric0.mnemonic = ZYDIS_MNEMONIC_INVALID;
transforms[ transform::type::generic0 ] = generic0 != key_transform ? generic0->instr : nogeneric0;
transforms[ transform::type::generic0 ] = generic0 != transform_instr ? generic0->instr : nogeneric0;
// last transformation is the same as the first except src and dest are swwapped...
transforms[ transform::type::rolling_key ] = key_transform->instr;
auto instr_copy = key_transform->instr;
instr_copy.operands[ 0 ].reg.value = key_transform->instr.operands[ 1 ].reg.value;
instr_copy.operands[ 1 ].reg.value = key_transform->instr.operands[ 0 ].reg.value;
transforms[ transform::type::rolling_key ] = transform_instr->instr;
auto instr_copy = transform_instr->instr;
instr_copy.operands[ 0 ].reg.value = transform_instr->instr.operands[ 1 ].reg.value;
instr_copy.operands[ 1 ].reg.value = transform_instr->instr.operands[ 0 ].reg.value;
transforms[ transform::type::update_key ] = instr_copy;
// three generic transformations...
auto generic_transform = key_transform;
for ( auto idx = 2u; idx < 5; ++idx )
for ( auto idx = static_cast< unsigned >( vm::transform::type::generic1 );
idx < static_cast< unsigned >( vm::transform::type::update_key ); ++idx )
{
generic_transform =
std::find_if( ++generic_transform, vm_handler.end(), []( const zydis_instr_t &instr_data ) -> bool {
if ( util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX ) )
return true;
return false;
transform_instr =
std::find_if( ++transform_instr, vm_handler.end(), []( const zydis_instr_t &instr_data ) -> bool {
return vm::transform::valid( instr_data.instr.mnemonic ) &&
instr_data.instr.operands[0].actions & ZYDIS_OPERAND_ACTION_WRITE &&
util::reg::compare( instr_data.instr.operands[ 0 ].reg.value, ZYDIS_REGISTER_RAX );
} );
if ( generic_transform == vm_handler.end() )
if ( transform_instr == vm_handler.end() )
return false;
transforms[ ( transform::type )( idx ) ] = generic_transform->instr;
transforms[ static_cast< vm::transform::type >( idx ) ] = transform_instr->instr;
}
return true;
@ -255,13 +252,10 @@ namespace vm
std::find_if( vm_entry.begin(), vm_entry.end(), []( const zydis_instr_t &instr_data ) -> bool {
const auto instr = &instr_data.instr;
// lea r12, vm_handlers... (always r12)...
if ( instr->mnemonic == ZYDIS_MNEMONIC_LEA &&
instr->operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_R12 &&
!instr->raw.sib.base ) // no register used for the sib base...
return true;
return false;
return instr->mnemonic == ZYDIS_MNEMONIC_LEA &&
instr->operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_R12 &&
!instr->raw.sib.base; // no register used for the sib base...
} );
if ( result == vm_entry.end() )
@ -275,42 +269,34 @@ namespace vm
bool get_transform( const zydis_routine_t &vm_entry, zydis_decoded_instr_t *transform_instr )
{
zydis_register_t rcx_or_rdx = ZYDIS_REGISTER_NONE;
auto handler_fetch =
std::find_if( vm_entry.begin(), vm_entry.end(), [ & ]( const zydis_instr_t &instr_data ) -> bool {
const auto instr = &instr_data.instr;
if ( instr->mnemonic == ZYDIS_MNEMONIC_MOV && instr->operand_count == 2 &&
instr->operands[ 1 ].type == ZYDIS_OPERAND_TYPE_MEMORY &&
instr->operands[ 1 ].mem.base == ZYDIS_REGISTER_R12 &&
instr->operands[ 1 ].mem.index == ZYDIS_REGISTER_RAX &&
instr->operands[ 1 ].mem.scale == 8 &&
instr->operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
( instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_RDX ||
instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_RCX ) )
{
rcx_or_rdx = instr->operands[ 0 ].reg.value;
return true;
}
return false;
return instr->mnemonic == ZYDIS_MNEMONIC_MOV && instr->operand_count == 2 &&
instr->operands[ 1 ].type == ZYDIS_OPERAND_TYPE_MEMORY &&
instr->operands[ 1 ].mem.base == ZYDIS_REGISTER_R12 &&
instr->operands[ 1 ].mem.index == ZYDIS_REGISTER_RAX &&
instr->operands[ 1 ].mem.scale == 8 &&
instr->operands[ 0 ].type == ZYDIS_OPERAND_TYPE_REGISTER &&
( instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_RDX ||
instr->operands[ 0 ].reg.value == ZYDIS_REGISTER_RCX );
} );
// check to see if we found the fetch instruction and if the next instruction
// is not the end of the vector...
if ( handler_fetch == vm_entry.end() || ++handler_fetch == vm_entry.end() ||
if ( handler_fetch == vm_entry.end() ||
// must be RCX or RDX... else something went wrong...
( rcx_or_rdx != ZYDIS_REGISTER_RCX && rcx_or_rdx != ZYDIS_REGISTER_RDX ) )
( handler_fetch->instr.operands[ 0 ].reg.value != ZYDIS_REGISTER_RCX &&
handler_fetch->instr.operands[ 0 ].reg.value != ZYDIS_REGISTER_RDX ) )
return false;
// find the next instruction that writes to RCX or RDX...
// the register is determined by the vm handler fetch above...
auto handler_transform =
std::find_if( handler_fetch, vm_entry.end(), [ & ]( const zydis_instr_t &instr_data ) -> bool {
if ( instr_data.instr.operands[ 0 ].reg.value == rcx_or_rdx &&
instr_data.instr.operands[ 0 ].actions & ZYDIS_OPERAND_ACTION_WRITE )
return true;
return false;
return instr_data.instr.operands[ 0 ].reg.value ==
handler_fetch->instr.operands[ 0 ].reg.value &&
instr_data.instr.operands[ 0 ].actions & ZYDIS_OPERAND_ACTION_WRITE;
} );
if ( handler_transform == vm_entry.end() )

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