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@ -59,81 +59,42 @@ bool emu_t::init() {
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return true;
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}
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vm::instrs::vinstr_t emu_t::step() {
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m_single_step.m_toggle = true;
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bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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uc_err err;
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std::uintptr_t rip = m_vm->m_vm_entry_rva + m_vm->m_module_base,
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std::uintptr_t rip = vmenter_rva + m_vm->m_module_base,
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rsp = STACK_BASE + STACK_SIZE - PAGE_4KB;
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if ((err = uc_reg_write(uc, UC_X86_REG_RSP, &rsp))) {
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std::printf("> uc_reg_write error, reason = %d\n", err);
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return;
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return false;
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}
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if ((err = uc_reg_write(uc, UC_X86_REG_RIP, &rip))) {
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std::printf("> uc_reg_write error, reason = %d\n", err);
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return;
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return false;
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}
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cc_trace.m_uc = uc;
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cc_trace.m_vip = vip;
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cc_trace.m_vsp = vsp;
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vrtn.m_rva = vmenter_rva;
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m_vm_enter = true;
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// -- if there is already exists a cpu context back up then restore from it...
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if (m_single_step.cpu_context) {
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uc_context_restore(uc, m_single_step.cpu_context);
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uc_mem_write(uc, STACK_BASE, m_single_step.stack, STACK_SIZE);
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}
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// -- single step emulate...
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std::printf("> beginning execution at = %p\n", rip);
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if ((err = uc_emu_start(uc, rip, 0ull, 0ull, 0ull))) {
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std::printf("> error starting emu... reason = %d\n", err);
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return;
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}
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// -- allocate new memory context...
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if (!m_single_step.cpu_context) {
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uc_context* ctx;
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uc_context_alloc(uc, &ctx);
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m_single_step.cpu_context = ctx;
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}
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// -- save cpu and stack...
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uc_context_save(uc, m_single_step.cpu_context);
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uc_mem_read(uc, STACK_BASE, m_single_step.stack, STACK_SIZE);
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m_single_step.m_toggle = false;
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return vinstrs.back();
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}
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void emu_t::emulate() {
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uc_err err;
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std::uintptr_t rip = m_vm->m_vm_entry_rva + m_vm->m_module_base,
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rsp = STACK_BASE + STACK_SIZE - PAGE_4KB;
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if ((err = uc_reg_write(uc, UC_X86_REG_RSP, &rsp))) {
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std::printf("> uc_reg_write error, reason = %d\n", err);
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return;
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}
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if ((err = uc_reg_write(uc, UC_X86_REG_RIP, &rip))) {
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std::printf("> uc_reg_write error, reason = %d\n", err);
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return;
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}
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cc_trace.m_uc = uc;
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cc_trace.m_vip = vip;
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cc_trace.m_vsp = vsp;
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vm::instrs::vblk_t blk;
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blk.m_vip = {0ull, 0ull};
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blk.m_cpu = {nullptr, nullptr};
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cc_blk = &blk;
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std::printf("> beginning execution at = %p\n", rip);
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if ((err = uc_emu_start(uc, rip, 0ull, 0ull, 0ull))) {
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std::printf("> error starting emu... reason = %d\n", err);
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return;
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return false;
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}
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const auto jcc_result = has_jcc(vinstrs);
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std::printf("> blk address = %p\n", blk.m_vip.img_base);
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const auto jcc_result = has_jcc(blk.m_vinstrs);
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std::printf("> jcc result = %d\n", jcc_result.has_value());
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return true;
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}
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void emu_t::int_callback(uc_engine* uc, std::uint32_t intno, emu_t* obj) {
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@ -194,7 +155,10 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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uc_context_alloc(obj->uc, &cpu_ctx);
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uc_context_save(obj->uc, cpu_ctx);
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vm::instrs::emu_instr_t emu_instr{instr, cpu_ctx};
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std::uint8_t* stack = reinterpret_cast<std::uint8_t*>(malloc(STACK_SIZE));
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uc_mem_read(uc, STACK_BASE, stack, STACK_SIZE);
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vm::instrs::emu_instr_t emu_instr{instr, cpu_ctx, stack};
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obj->cc_trace.m_instrs.push_back(emu_instr);
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// RET or JMP REG means the end of a vm handler...
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@ -221,15 +185,37 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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obj->cc_trace.m_instrs.erase((rva_fetch + 1).base(),
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obj->cc_trace.m_instrs.end());
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// extract vip address out of the vm enter trace...
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if (obj->m_vm_enter) {
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auto vip_addr_set = std::find_if(
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obj->cc_trace.m_instrs.rbegin(), obj->cc_trace.m_instrs.rend(),
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[&vip = obj->vip](vm::instrs::emu_instr_t& emu_instr) -> bool {
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const auto& i = emu_instr.m_instr;
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return i.operands[0].type == ZYDIS_OPERAND_TYPE_REGISTER &&
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i.operands[0].reg.value == vip;
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});
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// get the cpu context from the instruction after the instruction that
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// writes to vip...
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--vip_addr_set;
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uc_context* backup;
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uc_context_alloc(uc, &backup);
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uc_context_save(uc, backup);
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uc_context_restore(uc, vip_addr_set->m_cpu);
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std::uintptr_t vip_addr = 0ull;
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uc_reg_read(uc, vm::instrs::reg_map[obj->vip], &vip_addr);
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obj->cc_blk->m_vip.rva = vip_addr -= obj->m_vm->m_module_base;
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obj->cc_blk->m_vip.img_base = vip_addr += obj->m_vm->m_image_base;
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uc_context_restore(uc, backup);
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uc_context_free(backup);
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obj->m_vm_enter = false;
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} else {
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const auto vinstr =
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vm::instrs::determine(obj->vip, obj->vsp, obj->cc_trace);
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zydis_rtn_t inst_stream;
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std::for_each(obj->cc_trace.m_instrs.begin(), obj->cc_trace.m_instrs.end(),
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[&](vm::instrs::emu_instr_t& instr) {
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inst_stream.push_back({instr.m_instr});
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});
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if (vinstr.mnemonic != vm::instrs::mnemonic_t::unknown) {
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if (vinstr.imm.has_imm)
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std::printf("> %s %p\n",
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@ -239,25 +225,52 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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std::printf("> %s\n",
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vm::instrs::get_profile(vinstr.mnemonic)->name.c_str());
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} else {
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zydis_rtn_t inst_stream;
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std::for_each(obj->cc_trace.m_instrs.begin(),
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obj->cc_trace.m_instrs.end(),
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[&](vm::instrs::emu_instr_t& instr) {
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inst_stream.push_back({instr.m_instr});
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});
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vm::utils::print(inst_stream);
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std::getchar();
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}
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obj->cc_trace.m_vip = obj->vip;
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obj->cc_trace.m_vsp = obj->vsp;
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obj->vinstrs.push_back(vinstr);
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obj->cc_blk->m_vinstrs.push_back(vinstr);
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if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp) {
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uc_context *b1, *b2;
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uc_context_alloc(uc, &b1);
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uc_context_alloc(uc, &b2);
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uc_context_save(uc, b1);
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uc_context_restore(uc, obj->cc_trace.m_instrs.begin()->m_cpu);
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uc_context_save(uc, b2);
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uc_context_restore(uc, b1);
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std::uint8_t* stack =
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reinterpret_cast<std::uint8_t*>(malloc(STACK_SIZE));
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std::memcpy(stack, obj->cc_trace.m_instrs.begin()->stack, STACK_SIZE);
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obj->cc_blk->m_cpu.ctx = b2;
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obj->cc_blk->m_cpu.stack = stack;
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}
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if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp ||
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vinstr.mnemonic == vm::instrs::mnemonic_t::vmexit)
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uc_emu_stop(obj->uc);
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}
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// -- free the trace since we will start a new one...
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std::for_each(obj->cc_trace.m_instrs.begin(), obj->cc_trace.m_instrs.end(),
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[&](const vm::instrs::emu_instr_t& instr) {
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uc_context_free(instr.m_cpu);
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free(instr.stack);
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});
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obj->cc_trace.m_instrs.clear();
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if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp ||
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vinstr.mnemonic == vm::instrs::mnemonic_t::vmexit ||
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obj->m_single_step.m_toggle)
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uc_emu_stop(obj->uc);
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}
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return true;
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}
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@ -315,7 +328,35 @@ std::optional<std::pair<std::uintptr_t, std::uintptr_t>> emu_t::has_jcc(
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: val;
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});
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std::printf("> number of LCONST = %d\n", lconst_num);
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if (lconst_num < 3)
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return {};
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const auto lconst1 = std::find_if(
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vinstrs.rbegin(), vinstrs.rend(), [&](vm::instrs::vinstr_t& v) -> bool {
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return v.mnemonic == vm::instrs::mnemonic_t::lconst && v.imm.size == 64;
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});
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const auto lconst2 = std::find_if(
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lconst1 + 1, vinstrs.rend(), [&](vm::instrs::vinstr_t& v) -> bool {
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return v.mnemonic == vm::instrs::mnemonic_t::lconst && v.imm.size == 64;
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});
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static const auto exec_callbk = [&](uc_engine* uc, uint64_t address,
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uint32_t size, emu_t* obj) {};
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uc_context *backup, *br1, *br2;
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uc_context_alloc(uc, &backup);
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uc_context_alloc(uc, &br1);
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uc_context_alloc(uc, &br2);
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uc_context_save(uc, backup);
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uc_context_restore(uc, cc_blk->m_cpu.ctx);
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uc_mem_write(uc, STACK_BASE, cc_blk->m_cpu.stack, STACK_SIZE);
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uc_context_restore(uc, backup);
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uc_context_free(backup);
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uc_context_free(br1);
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uc_context_free(br2);
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return {};
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}
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} // namespace vm
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