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@ -92,38 +92,8 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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return false;
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}
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auto br_info = could_have_jcc(cc_blk->m_vinstrs);
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if (br_info.has_value()) {
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auto [br1, br2] = br_info.value();
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// convert to absolute addresses...
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br1 -= m_vm->m_image_base;
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br2 -= m_vm->m_image_base;
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br1 += m_vm->m_module_base;
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br2 += m_vm->m_module_base;
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auto br1_legit = legit_branch(*cc_blk, br1);
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auto br2_legit = legit_branch(*cc_blk, br2);
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std::printf("> br1 legit: %d, br2 legit: %d\n", br1_legit, br2_legit);
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if (br1_legit && br2_legit) {
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std::printf("> virtual jcc uncovered... br1 = %p, br2 = %p\n", br1, br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::jcc;
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cc_blk->branches.push_back(br1);
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cc_blk->branches.push_back(br2);
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} else if (br1_legit || br2_legit) {
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std::printf("> absolute virtual jmp uncovered... branch = %p\n",
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br1_legit ? br1 : br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::absolute;
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cc_blk->branches.push_back(br1_legit ? br1 : br2);
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} else {
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std::printf("> unknown branch type...\n");
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return false;
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}
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} else if (cc_blk->m_vinstrs.back().mnemonic ==
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vm::instrs::mnemonic_t::vmexit) {
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cc_blk->branch_type = vm::instrs::vbranch_type::none;
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}
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extract_branch_data();
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std::printf("> emulated blk_%p\n\n", cc_blk->m_vip.img_base);
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// keep track of the emulated blocks... by their addresses...
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std::vector<std::uintptr_t> blk_addrs;
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@ -134,11 +104,6 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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for (auto idx = 0u; idx < cc_vrtn->m_blks.size(); ++idx) {
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vm::instrs::vblk_t blk = cc_vrtn->m_blks[idx];
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if (blk.branch_type != vm::instrs::vbranch_type::none) {
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std::uintptr_t vsp = 0ull;
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uc_context_restore(uc, blk.m_jmp.ctx);
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uc_mem_write(uc, STACK_BASE, blk.m_jmp.stack, STACK_SIZE);
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uc_reg_read(uc, vm::instrs::reg_map[blk.m_vm.vsp], &vsp);
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// force the emulation of all branches...
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for (const auto br : blk.branches) {
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// only emulate blocks that havent been emulated before...
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@ -146,6 +111,11 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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blk_addrs.end())
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continue;
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std::uintptr_t vsp = 0ull;
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uc_context_restore(uc, blk.m_jmp.ctx);
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uc_mem_write(uc, STACK_BASE, blk.m_jmp.stack, STACK_SIZE);
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uc_reg_read(uc, vm::instrs::reg_map[blk.m_vm.vsp], &vsp);
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// setup new cc_blk...
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auto& new_blk = vrtn.m_blks.emplace_back();
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new_blk.m_vip = {0ull, 0ull};
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@ -154,41 +124,14 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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// emulate the branch...
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uc_mem_write(uc, vsp, &br, sizeof br);
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uc_emu_start(uc, blk.m_jmp.rip, 0ull, 0ull, 0ull);
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auto br_info = could_have_jcc(cc_blk->m_vinstrs);
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if (br_info.has_value()) {
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auto [br1, br2] = br_info.value();
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// convert to absolute addresses...
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br1 -= m_vm->m_image_base;
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br2 -= m_vm->m_image_base;
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br1 += m_vm->m_module_base;
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br2 += m_vm->m_module_base;
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auto br1_legit = legit_branch(*cc_blk, br1);
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auto br2_legit = legit_branch(*cc_blk, br2);
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std::printf("> br1 legit: %d, br2 legit: %d\n", br1_legit, br2_legit);
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if (br1_legit && br2_legit) {
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std::printf("> virtual jcc uncovered... br1 = %p, br2 = %p\n", br1,
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br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::jcc;
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cc_blk->branches.push_back(br1);
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cc_blk->branches.push_back(br2);
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} else if (br1_legit || br2_legit) {
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std::printf("> absolute virtual jmp uncovered... branch = %p\n",
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br1_legit ? br1 : br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::absolute;
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cc_blk->branches.push_back(br1_legit ? br1 : br2);
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} else {
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std::printf("> unknown branch type...\n");
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return false;
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}
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} else if (cc_blk->m_vinstrs.back().mnemonic ==
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vm::instrs::mnemonic_t::vmexit) {
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cc_blk->branch_type = vm::instrs::vbranch_type::none;
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std::printf("> beginning execution at = %p\n", blk.m_jmp.rip);
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if ((err = uc_emu_start(uc, blk.m_jmp.rip, 0ull, 0ull, 0ull))) {
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std::printf("> error starting emu... reason = %d\n", err);
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return false;
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}
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extract_branch_data();
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std::printf("> emulated blk_%p\n", cc_blk->m_vip.img_base);
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}
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}
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}
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@ -206,6 +149,65 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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return true;
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}
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void emu_t::extract_branch_data() {
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auto br_info = could_have_jcc(cc_blk->m_vinstrs);
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if (br_info.has_value()) {
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auto [br1, br2] = br_info.value();
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// convert to absolute addresses...
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br1 -= m_vm->m_image_base;
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br2 -= m_vm->m_image_base;
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br1 += m_vm->m_module_base;
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br2 += m_vm->m_module_base;
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auto br1_legit = legit_branch(*cc_blk, br1);
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auto br2_legit = legit_branch(*cc_blk, br2);
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std::printf("> br1 legit: %d, br2 legit: %d\n", br1_legit, br2_legit);
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if (br1_legit && br2_legit) {
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std::printf("> virtual jcc uncovered... br1 = %p, br2 = %p\n", br1, br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::jcc;
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cc_blk->branches.push_back(br1);
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cc_blk->branches.push_back(br2);
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} else if (br1_legit || br2_legit) {
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std::printf("> absolute virtual jmp uncovered... branch = %p\n",
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br1_legit ? br1 : br2);
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cc_blk->branch_type = vm::instrs::vbranch_type::absolute;
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cc_blk->branches.push_back(br1_legit ? br1 : br2);
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} else {
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std::printf("> unknown branch type...\n");
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}
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} else if (cc_blk->m_vinstrs.back().mnemonic ==
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vm::instrs::mnemonic_t::vmexit) {
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cc_blk->branch_type = vm::instrs::vbranch_type::none;
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} else if (cc_blk->m_vinstrs.back().mnemonic == vm::instrs::mnemonic_t::jmp) {
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// see if there is 1 lconst...
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if (auto last_lconst = std::find_if(
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cc_blk->m_vinstrs.rbegin(), cc_blk->m_vinstrs.rend(),
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[&](vm::instrs::vinstr_t& vinstr) -> bool {
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return vinstr.mnemonic == vm::instrs::mnemonic_t::lconst &&
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vinstr.imm.size == 64;
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});
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last_lconst != cc_blk->m_vinstrs.rend()) {
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const auto imm_img_based = last_lconst->imm.val;
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const auto imm_mod_based =
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(imm_img_based - m_vm->m_image_base) + m_vm->m_module_base;
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// check to see if the imm is inside of the module... and if the ptr lands
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// inside of an executable section... then lastly check to see if its a
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// legit branch or not...
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if (imm_img_based >= m_vm->m_image_base &&
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imm_img_based < m_vm->m_image_base + m_vm->m_image_size &&
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vm::utils::scn::executable(m_vm->m_module_base, imm_mod_based)) {
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cc_blk->branches.push_back(imm_mod_based);
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cc_blk->branch_type = vm::instrs::vbranch_type::absolute;
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}
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} else {
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std::printf("> jump table detected... review instruction stream...\n");
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uc_emu_stop(uc);
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}
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}
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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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uc_err err;
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std::uintptr_t rip = 0ull;
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@ -395,13 +397,10 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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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_write->m_cpu);
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auto uc_reg =
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vm::instrs::reg_map[vip_write->m_instr.operands[0].reg.value];
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uc_context_restore(uc, (--vip_write)->m_cpu);
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std::uintptr_t vip_addr = 0ull;
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uc_reg_read(uc, uc_reg, &vip_addr);
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uc_reg_read(uc, vm::instrs::reg_map[obj->cc_trace.m_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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