#include "std_include.hpp" #include "windows_emulator.hpp" #include "context_frame.hpp" #include constexpr auto MAX_INSTRUCTIONS_PER_TIME_SLICE = 10000; namespace { template emulator_object allocate_object_on_stack(x64_emulator& emu) { const auto old_sp = emu.reg(x64_register::rsp); const auto new_sp = align_down(old_sp - sizeof(CONTEXT), std::max(alignof(CONTEXT), alignof(x64_emulator::pointer_type))); emu.reg(x64_register::rsp, new_sp); return {emu, new_sp}; } void unalign_stack(x64_emulator& emu) { auto sp = emu.reg(x64_register::rsp); sp = align_down(sp - 0x10, 0x10) + 8; emu.reg(x64_register::rsp, sp); } void setup_stack(x64_emulator& emu, const uint64_t stack_base, const size_t stack_size) { const uint64_t stack_end = stack_base + stack_size; emu.reg(x64_register::rsp, stack_end); } void setup_gs_segment(x64_emulator& emu, const emulator_allocator& allocator) { struct msr_value { uint32_t id; uint64_t value; }; const msr_value value{ IA32_GS_BASE_MSR, allocator.get_base() }; emu.write_register(x64_register::msr, &value, sizeof(value)); } emulator_object setup_kusd(x64_emulator& emu) { emu.allocate_memory(KUSD_ADDRESS, page_align_up(sizeof(KUSER_SHARED_DATA)), memory_permission::read); const emulator_object kusd_object{emu, KUSD_ADDRESS}; kusd_object.access([](KUSER_SHARED_DATA& kusd) { const auto& real_kusd = *reinterpret_cast(KUSD_ADDRESS); memcpy(&kusd, &real_kusd, sizeof(kusd)); kusd.ImageNumberLow = IMAGE_FILE_MACHINE_I386; kusd.ImageNumberHigh = IMAGE_FILE_MACHINE_AMD64; memset(&kusd.ProcessorFeatures, 0, sizeof(kusd.ProcessorFeatures)); // ... }); return kusd_object; } uint64_t copy_string(x64_emulator& emu, emulator_allocator& allocator, const void* base_ptr, const uint64_t offset, const size_t length) { if (!length) { return 0; } const auto length_to_allocate = length + 2; const auto str_obj = allocator.reserve(length_to_allocate); emu.write_memory(str_obj, static_cast(base_ptr) + offset, length); return str_obj; } ULONG copy_string_as_relative(x64_emulator& emu, emulator_allocator& allocator, const uint64_t result_base, const void* base_ptr, const uint64_t offset, const size_t length) { const auto address = copy_string(emu, allocator, base_ptr, offset, length); if (!address) { return 0; } assert(address > result_base); return static_cast(address - result_base); } emulator_object clone_api_set_map(x64_emulator& emu, emulator_allocator& allocator, const API_SET_NAMESPACE& orig_api_set_map) { const auto api_set_map_obj = allocator.reserve(); const auto ns_entries_obj = allocator.reserve(orig_api_set_map.Count); const auto hash_entries_obj = allocator.reserve(orig_api_set_map.Count); api_set_map_obj.access([&](API_SET_NAMESPACE& api_set) { api_set = orig_api_set_map; api_set.EntryOffset = static_cast(ns_entries_obj.value() - api_set_map_obj.value()); api_set.HashOffset = static_cast(hash_entries_obj.value() - api_set_map_obj.value()); }); const auto orig_ns_entries = offset_pointer(&orig_api_set_map, orig_api_set_map.EntryOffset); const auto orig_hash_entries = offset_pointer(&orig_api_set_map, orig_api_set_map.HashOffset); for (ULONG i = 0; i < orig_api_set_map.Count; ++i) { auto ns_entry = orig_ns_entries[i]; const auto hash_entry = orig_hash_entries[i]; ns_entry.NameOffset = copy_string_as_relative(emu, allocator, api_set_map_obj.value(), &orig_api_set_map, ns_entry.NameOffset, ns_entry.NameLength); if (!ns_entry.ValueCount) { continue; } const auto values_obj = allocator.reserve(ns_entry.ValueCount); const auto orig_values = offset_pointer(&orig_api_set_map, ns_entry.ValueOffset); ns_entry.ValueOffset = static_cast(values_obj.value() - api_set_map_obj.value()); for (ULONG j = 0; j < ns_entry.ValueCount; ++j) { auto value = orig_values[j]; value.ValueOffset = copy_string_as_relative(emu, allocator, api_set_map_obj.value(), &orig_api_set_map, value.ValueOffset, value.ValueLength); if (value.NameLength) { value.NameOffset = copy_string_as_relative(emu, allocator, api_set_map_obj.value(), &orig_api_set_map, value.NameOffset, value.NameLength); } values_obj.write(value, j); } ns_entries_obj.write(ns_entry, i); hash_entries_obj.write(hash_entry, i); } return api_set_map_obj; } emulator_object build_api_set_map(x64_emulator& emu, emulator_allocator& allocator) { const auto& orig_api_set_map = *NtCurrentTeb()->ProcessEnvironmentBlock->ApiSetMap; return clone_api_set_map(emu, allocator, orig_api_set_map); } emulator_allocator create_allocator(emulator& emu, const size_t size) { const auto base = emu.find_free_allocation_base(size); emu.allocate_memory(base, size, memory_permission::read_write); return emulator_allocator{emu, base, size}; } void setup_gdt(x64_emulator& emu) { constexpr uint64_t gdtr[4] = {0, GDT_ADDR, GDT_LIMIT, 0}; emu.write_register(x64_register::gdtr, &gdtr, sizeof(gdtr)); emu.allocate_memory(GDT_ADDR, GDT_LIMIT, memory_permission::read); emu.write_memory(GDT_ADDR + 6 * (sizeof(uint64_t)), 0xEFFE000000FFFF); emu.reg(x64_register::cs, 0x33); emu.write_memory(GDT_ADDR + 5 * (sizeof(uint64_t)), 0xEFF6000000FFFF); emu.reg(x64_register::ss, 0x2B); } void setup_context(process_context& context, x64_emulator& emu, const std::filesystem::path& file, const std::vector& arguments) { setup_gdt(emu); context.kusd = setup_kusd(emu); context.base_allocator = create_allocator(emu, PEB_SEGMENT_SIZE); auto& allocator = context.base_allocator; context.peb = allocator.reserve(); /* Values of the following fields must be * allocated relative to the process_params themselves * and included in the length: * * CurrentDirectory * DllPath * ImagePathName * CommandLine * WindowTitle * DesktopInfo * ShellInfo * RuntimeData * RedirectionDllName */ context.process_params = allocator.reserve(); context.process_params.access([&](RTL_USER_PROCESS_PARAMETERS& proc_params) { proc_params.Flags = 0x6001; //| 0x80000000; // Prevent CsrClientConnectToServer proc_params.ConsoleHandle = CONSOLE_HANDLE.h; proc_params.StandardOutput = STDOUT_HANDLE.h; proc_params.StandardInput = STDIN_HANDLE.h; proc_params.StandardError = proc_params.StandardOutput; proc_params.Environment = allocator.copy_string(L"=::=::\\"); allocator.copy_string(L"EMULATOR=1"); allocator.copy_string(L"COMPUTERNAME=momo"); allocator.copy_string(L""); std::wstring command_line = L"\"" + file.wstring() + L"\""; for (const auto& arg : arguments) { command_line.push_back(L' '); command_line.append(arg); } const auto current_folder = canonical(absolute(file).parent_path()).make_preferred().wstring() + L"\\"; allocator.make_unicode_string(proc_params.CommandLine, command_line); allocator.make_unicode_string(proc_params.CurrentDirectory.DosPath, current_folder); allocator.make_unicode_string(proc_params.ImagePathName, file.wstring()); const auto total_length = allocator.get_next_address() - context.process_params.value(); proc_params.Length = static_cast(std::max(sizeof(proc_params), total_length)); proc_params.MaximumLength = proc_params.Length; }); context.peb.access([&](PEB& peb) { peb.ImageBaseAddress = nullptr; peb.ProcessParameters = context.process_params.ptr(); peb.ApiSetMap = build_api_set_map(emu, allocator).ptr(); peb.ProcessHeap = nullptr; peb.ProcessHeaps = nullptr; peb.HeapSegmentReserve = 0x0000000000100000; // TODO: Read from executable peb.HeapSegmentCommit = 0x0000000000002000; peb.HeapDeCommitTotalFreeThreshold = 0x0000000000010000; peb.HeapDeCommitFreeBlockThreshold = 0x0000000000001000; peb.NumberOfHeaps = 0x00000000; peb.MaximumNumberOfHeaps = 0x00000010; }); } using exception_record_map = std::unordered_map>; emulator_object save_exception_record(emulator_allocator& allocator, const EXCEPTION_RECORD& record, exception_record_map& record_mapping) { const auto record_obj = allocator.reserve(); record_obj.write(record); if (record.ExceptionRecord) { record_mapping[&record] = record_obj; emulator_object nested_record_obj{}; const auto nested_record = record_mapping.find(record.ExceptionRecord); if (nested_record != record_mapping.end()) { nested_record_obj = nested_record->second; } else { nested_record_obj = save_exception_record(allocator, *record.ExceptionRecord, record_mapping); } record_obj.access([&](EXCEPTION_RECORD& r) { r.ExceptionRecord = nested_record_obj.ptr(); }); } return record_obj; } emulator_object save_exception_record(emulator_allocator& allocator, const EXCEPTION_RECORD& record) { exception_record_map record_mapping{}; return save_exception_record(allocator, record, record_mapping); } uint32_t map_violation_operation_to_parameter(const memory_operation operation) { switch (operation) { default: case memory_operation::read: return 0; case memory_operation::write: case memory_operation::exec: return 1; } } size_t calculate_exception_record_size(const EXCEPTION_RECORD& record) { std::unordered_set records{}; size_t total_size = 0; const EXCEPTION_RECORD* current_record = &record; while (current_record) { if (!records.insert(current_record).second) { break; } total_size += sizeof(*current_record); current_record = record.ExceptionRecord; } return total_size; } struct machine_frame { uint64_t rip; uint64_t cs; uint64_t eflags; uint64_t rsp; uint64_t ss; }; void dispatch_exception_pointers(x64_emulator& emu, const uint64_t dispatcher, const EXCEPTION_POINTERS pointers) { constexpr auto mach_frame_size = 0x40; constexpr auto context_record_size = 0x4F0; const auto exception_record_size = calculate_exception_record_size(*pointers.ExceptionRecord); const auto combined_size = align_up(exception_record_size + context_record_size, 0x10); assert(combined_size == 0x590); const auto allocation_size = combined_size + mach_frame_size; const auto initial_sp = emu.reg(x64_register::rsp); const auto new_sp = align_down(initial_sp - allocation_size, 0x100); const auto total_size = initial_sp - new_sp; assert(total_size >= allocation_size); std::vector zero_memory{}; zero_memory.resize(total_size, 0); emu.write_memory(new_sp, zero_memory.data(), zero_memory.size()); emu.reg(x64_register::rsp, new_sp); emu.reg(x64_register::rip, dispatcher); const emulator_object context_record_obj{emu, new_sp}; context_record_obj.write(*pointers.ContextRecord); emulator_allocator allocator{emu, new_sp + context_record_size, exception_record_size}; const auto exception_record_obj = save_exception_record(allocator, *pointers.ExceptionRecord); if (exception_record_obj.value() != allocator.get_base()) { throw std::runtime_error("Bad exception record position on stack"); } const emulator_object machine_frame_obj{emu, new_sp + combined_size}; machine_frame_obj.access([&](machine_frame& frame) { frame.rip = pointers.ContextRecord->Rip; frame.rsp = pointers.ContextRecord->Rsp; frame.ss = pointers.ContextRecord->SegSs; frame.cs = pointers.ContextRecord->SegCs; frame.eflags = pointers.ContextRecord->EFlags; }); } void dispatch_access_violation(x64_emulator& emu, const uint64_t dispatcher, const uint64_t address, const memory_operation operation) { CONTEXT ctx{}; ctx.ContextFlags = CONTEXT_ALL; context_frame::save(emu, ctx); EXCEPTION_RECORD record{}; memset(&record, 0, sizeof(record)); record.ExceptionCode = static_cast(STATUS_ACCESS_VIOLATION); record.ExceptionFlags = 0; record.ExceptionRecord = nullptr; record.ExceptionAddress = reinterpret_cast(emu.read_instruction_pointer()); record.NumberParameters = 2; record.ExceptionInformation[0] = map_violation_operation_to_parameter(operation); record.ExceptionInformation[1] = address; EXCEPTION_POINTERS pointers{}; pointers.ContextRecord = &ctx; pointers.ExceptionRecord = &record; dispatch_exception_pointers(emu, dispatcher, pointers); } bool switch_to_thread(const logger& logger, x64_emulator& emu, process_context& context, emulator_thread& thread) { if (!thread.is_thread_ready(context)) { return false; } auto* active_thread = context.active_thread; if (active_thread == &thread) { thread.setup_if_necessary(emu, context); return true; } logger.print(color::green, "Performing thread switch...\n"); if (active_thread) { active_thread->save(emu); } context.active_thread = &thread; thread.restore(emu); thread.setup_if_necessary(emu, context); return true; } bool switch_to_thread(const logger& logger, x64_emulator& emu, process_context& context, const handle thread_handle) { auto* thread = context.threads.get(thread_handle); if (!thread) { throw std::runtime_error("Bad thread handle"); } return switch_to_thread(logger, emu, context, *thread); } bool switch_to_next_thread(const logger& logger, x64_emulator& emu, process_context& context) { bool next_thread = false; for (auto& thread : context.threads) { if (next_thread) { if (switch_to_thread(logger, emu, context, thread.second)) { return true; } continue; } if (&thread.second == context.active_thread) { next_thread = true; } } for (auto& thread : context.threads) { if (switch_to_thread(logger, emu, context, thread.second)) { return true; } } return false; } bool is_object_signaled(process_context& c, const handle h) { const auto type = h.value.type; switch (type) { default: break; case handle_types::event: { const auto* e = c.events.get(h); if (e) { return e->signaled; } break; } case handle_types::thread: { const auto* t = c.threads.get(h); if (t) { return t->exit_status.has_value(); } break; } } throw std::runtime_error("Bad object"); } } emulator_thread::emulator_thread(x64_emulator& emu, const process_context& context, const uint64_t start_address, const uint64_t argument, const uint64_t stack_size, const uint32_t id) : emu_ptr(&emu) , stack_size(page_align_up(std::max(stack_size, STACK_SIZE))) , start_address(start_address) , argument(argument) , id(id) , last_registers(context.default_register_set) { this->stack_base = emu.allocate_memory(this->stack_size, memory_permission::read_write); this->gs_segment = emulator_allocator{ emu, emu.allocate_memory(GS_SEGMENT_SIZE, memory_permission::read_write), GS_SEGMENT_SIZE, }; this->teb = this->gs_segment->reserve(); this->teb->access([&](TEB& teb_obj) { teb_obj.ClientId.UniqueProcess = reinterpret_cast(1); teb_obj.ClientId.UniqueThread = reinterpret_cast(static_cast(this->id)); teb_obj.NtTib.StackLimit = reinterpret_cast(this->stack_base); teb_obj.NtTib.StackBase = reinterpret_cast(this->stack_base + this->stack_size); teb_obj.NtTib.Self = &this->teb->ptr()->NtTib; teb_obj.ProcessEnvironmentBlock = context.peb.ptr(); }); } void emulator_thread::mark_as_ready(const NTSTATUS status) { this->pending_status = status; this->await_time = {}; this->await_object = {}; // TODO: Find out if this is correct if (this->waiting_for_alert) { this->alerted = false; } this->waiting_for_alert = false; } bool emulator_thread::is_thread_ready(process_context& context) { if(this->exit_status.has_value()) { return false; } if (this->waiting_for_alert) { if (this->alerted) { this->mark_as_ready(STATUS_ALERTED); return true; } if (this->is_await_time_over()) { this->mark_as_ready(STATUS_TIMEOUT); return true; } return false; } if (this->await_object.has_value()) { if (is_object_signaled(context, *this->await_object)) { this->mark_as_ready(STATUS_WAIT_0); return true; } if (this->is_await_time_over()) { this->mark_as_ready(STATUS_TIMEOUT); return true; } return false; } if (this->await_time.has_value()) { if (this->is_await_time_over()) { this->mark_as_ready(STATUS_SUCCESS); return true; } return false; } return true; } void emulator_thread::setup_registers(x64_emulator& emu, const process_context& context) const { setup_stack(emu, this->stack_base, this->stack_size); setup_gs_segment(emu, *this->gs_segment); CONTEXT ctx{}; ctx.ContextFlags = CONTEXT_ALL; unalign_stack(emu); context_frame::save(emu, ctx); ctx.Rip = context.rtl_user_thread_start; ctx.Rcx = this->start_address; ctx.Rdx = this->argument; const auto ctx_obj = allocate_object_on_stack(emu); ctx_obj.write(ctx); unalign_stack(emu); emu.reg(x64_register::rcx, ctx_obj.value()); emu.reg(x64_register::rdx, context.ntdll->image_base); emu.reg(x64_register::rip, context.ldr_initialize_thunk); } std::unique_ptr create_default_x64_emulator() { return unicorn::create_x64_emulator(); } windows_emulator::windows_emulator(const std::filesystem::path& application, const std::vector& arguments, std::unique_ptr emu) : windows_emulator(std::move(emu)) { this->setup_process(application, arguments); } windows_emulator::windows_emulator(std::unique_ptr emu) : emu_(std::move(emu)) , process_(*emu_) { this->setup_hooks(); } void windows_emulator::setup_process(const std::filesystem::path& application, const std::vector& arguments) { auto& emu = this->emu(); auto& context = this->process(); context.module_manager = module_manager(emu); // TODO: Cleanup module manager setup_context(context, emu, application, arguments); context.executable = context.module_manager.map_module(application, this->logger); context.peb.access([&](PEB& peb) { peb.ImageBaseAddress = reinterpret_cast(context.executable->image_base); }); context.ntdll = context.module_manager.map_module(R"(C:\Windows\System32\ntdll.dll)", this->logger); context.win32u = context.module_manager.map_module(R"(C:\Windows\System32\win32u.dll)", this->logger); this->dispatcher_.setup(context.ntdll->exports, context.win32u->exports); context.ldr_initialize_thunk = context.ntdll->find_export("LdrInitializeThunk"); context.rtl_user_thread_start = context.ntdll->find_export("RtlUserThreadStart"); context.ki_user_exception_dispatcher = context.ntdll->find_export("KiUserExceptionDispatcher"); context.default_register_set = emu.save_registers(); const auto main_thread_id = context.create_thread(emu, context.executable->entry_point, 0, 0); switch_to_thread(this->logger, emu, context, main_thread_id); } void windows_emulator::perform_thread_switch() { this->switch_thread = false; while (!switch_to_next_thread(this->logger, this->emu(), this->process())) { // TODO: Optimize that std::this_thread::sleep_for(1ms); } } void windows_emulator::setup_hooks() { this->emu().hook_instruction(x64_hookable_instructions::syscall, [&] { for (const auto& hook : this->syscall_hooks_) { if (hook() == instruction_hook_continuation::skip_instruction) { return instruction_hook_continuation::skip_instruction; } } this->dispatcher_.dispatch(*this); return instruction_hook_continuation::skip_instruction; }); this->emu().hook_instruction(x64_hookable_instructions::invalid, [&] { const auto ip = this->emu().read_instruction_pointer(); printf("Invalid instruction at: 0x%llX\n", ip); return instruction_hook_continuation::skip_instruction; }); this->emu().hook_interrupt([&](const int interrupt) { const auto rip = this->emu().read_instruction_pointer(); printf("Interrupt: %i 0x%llX\n", interrupt, rip); if (this->fuzzing) { this->process().exception_rip = rip; this->emu().stop(); } }); this->emu().hook_memory_violation([&](const uint64_t address, const size_t size, const memory_operation operation, const memory_violation_type type) { const auto permission = get_permission_string(operation); const auto ip = this->emu().read_instruction_pointer(); const char* name = this->process().module_manager.find_name(ip); if (type == memory_violation_type::protection) { printf("Protection violation: 0x%llX (%zX) - %s at 0x%llX (%s)\n", address, size, permission.c_str(), ip, name); } else if (type == memory_violation_type::unmapped) { printf("Mapping violation: 0x%llX (%zX) - %s at 0x%llX (%s)\n", address, size, permission.c_str(), ip, name); } if (this->fuzzing) { this->process().exception_rip = ip; this->emu().stop(); return memory_violation_continuation::stop; } dispatch_access_violation(this->emu(), this->process().ki_user_exception_dispatcher, address, operation); return memory_violation_continuation::resume; }); this->emu().hook_memory_execution(0, std::numeric_limits::max(), [&](const uint64_t address, const size_t, const uint64_t) { auto& process = this->process(); auto& thread = this->current_thread(); ++process.executed_instructions; const auto thread_insts = ++thread.executed_instructions; if (thread_insts % MAX_INSTRUCTIONS_PER_TIME_SLICE == 0) { this->switch_thread = true; this->emu().stop(); } process.previous_ip = process.current_ip; process.current_ip = this->emu().read_instruction_pointer(); const auto is_interesting_call = process.executable->is_within( process.previous_ip) || process.executable->is_within(address); /*if (address == 0x180038B65) { puts("!!! DLL init failed"); } if (address == 0x180038A20) { const auto* name = this->process().module_manager.find_name( this->emu().reg(x64_register::rcx)); printf("!!! DLL init: %s\n", name); }*/ if (!this->verbose && !this->verbose_calls && !is_interesting_call) { return; } const auto* binary = this->process().module_manager.find_by_address(address); if (binary) { const auto export_entry = binary->address_names.find(address); if (export_entry != binary->address_names.end()) { logger.print(is_interesting_call ? color::yellow : color::dark_gray, "Executing function: %s - %s (0x%llX)\n", binary->name.c_str(), export_entry->second.c_str(), address); } else if (address == binary->entry_point) { logger.print(is_interesting_call ? color::yellow : color::gray, "Executing entry point: %s (0x%llX)\n", binary->name.c_str(), address); } } if (!this->verbose) { return; } auto& emu = this->emu(); printf( "Inst: %16llX - RAX: %16llX - RBX: %16llX - RCX: %16llX - RDX: %16llX - R8: %16llX - R9: %16llX - RDI: %16llX - RSI: %16llX - %s\n", address, emu.reg(x64_register::rax), emu.reg(x64_register::rbx), emu.reg(x64_register::rcx), emu.reg(x64_register::rdx), emu.reg(x64_register::r8), emu.reg(x64_register::r9), emu.reg(x64_register::rdi), emu.reg(x64_register::rsi), binary ? binary->name.c_str() : ""); }); } void windows_emulator::start(std::chrono::nanoseconds timeout, size_t count) { const auto use_count = count > 0; const auto use_timeout = timeout != std::chrono::nanoseconds{}; auto start_time = std::chrono::high_resolution_clock::now(); auto start_instructions = this->process().executed_instructions; while (true) { if (this->switch_thread) { this->perform_thread_switch(); } this->emu().start_from_ip(timeout, count); if (!this->switch_thread) { break; } if (use_timeout) { const auto now = std::chrono::high_resolution_clock::now(); const auto diff = now - start_time; if (diff >= timeout) { break; } timeout = timeout - diff; start_time = now; } if (use_count) { const auto current_instructions = this->process().executed_instructions; const auto diff = current_instructions - start_instructions; if(diff >= count) { break; } count = diff; start_instructions = current_instructions; } } } void windows_emulator::serialize(utils::buffer_serializer& buffer) const { this->emu().serialize(buffer); this->process_.serialize(buffer); this->dispatcher_.serialize(buffer); } void windows_emulator::deserialize(utils::buffer_deserializer& buffer) { this->emu().deserialize(buffer); this->process_.deserialize(buffer); this->dispatcher_.deserialize(buffer); } void windows_emulator::save_snapshot() { this->emu().save_snapshot(); utils::buffer_serializer serializer{}; this->process_.serialize(serializer); this->process_snapshot_ = serializer.move_buffer(); // TODO: Make process copyable //this->process_snapshot_ = this->process(); } void windows_emulator::restore_snapshot() { if (this->process_snapshot_.empty()) { assert(false); return; } this->emu().restore_snapshot(); utils::buffer_deserializer deserializer{this->process_snapshot_}; this->process_.deserialize(deserializer); //this->process_ = *this->process_snapshot_; }