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@ -78,12 +78,12 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
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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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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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cc_vrtn = &vrtn;
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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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@ -91,9 +91,9 @@ 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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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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std::printf(
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"> blk_%p, number of virtual instructions = %d, could have a jcc = %d\n",
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blk.m_vip.img_base, blk.m_vinstrs.size(), could_have_jcc(blk.m_vinstrs));
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return true;
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}
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@ -148,18 +148,17 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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if (instr.mnemonic == ZYDIS_MNEMONIC_INVALID)
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return false;
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// save the current cpu's context (all register values and such)...
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// create a new emu_instr_t with this information... this info will be used by
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// profiles to grab decrypted values and such...
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uc_context* cpu_ctx;
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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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uc_context* ctx;
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uc_context_alloc(uc, &ctx);
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uc_context_save(uc, 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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// if this is the first instruction of this handler then save the stack...
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if (!obj->cc_trace.m_instrs.size()) {
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obj->cc_trace.m_stack = reinterpret_cast<std::uint8_t*>(malloc(STACK_SIZE));
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uc_mem_read(uc, STACK_BASE, obj->cc_trace.m_stack, STACK_SIZE);
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}
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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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obj->cc_trace.m_instrs.push_back({instr, ctx});
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// RET or JMP REG means the end of a vm handler...
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if (instr.mnemonic == ZYDIS_MNEMONIC_RET ||
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@ -185,33 +184,32 @@ 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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// set the virtual code block vip address information...
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if (!obj->cc_blk->m_vip.rva || !obj->cc_blk->m_vip.img_base) {
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auto vip_write = 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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[&vip = obj->vip](vm::instrs::emu_instr_t& instr) -> bool {
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const auto& i = 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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uc_context_restore(uc, (vip_write - 1)->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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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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uc_reg_read(uc, uc_reg, &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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@ -241,21 +239,25 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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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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uc_context *backup, *copy;
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std::uint8_t* stack =
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reinterpret_cast<std::uint8_t*>(malloc(STACK_SIZE));
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// backup current unicorn-engine context...
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uc_context_alloc(uc, &backup);
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uc_context_alloc(uc, ©);
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uc_context_save(uc, backup);
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std::memcpy(stack, obj->cc_trace.m_instrs.begin()->stack, STACK_SIZE);
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// make a copy of the first cpu context of the jmp handler...
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uc_context_restore(uc, obj->cc_trace.m_instrs.begin()->m_cpu);
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uc_context_save(uc, copy);
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// restore the unicorn-engine context... also free the backup...
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uc_context_restore(uc, backup);
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uc_context_free(backup);
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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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// set current code block virtual jmp instruction information...
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obj->cc_blk->m_jmp.ctx = copy;
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obj->cc_blk->m_jmp.stack = new std::uint8_t[STACK_SIZE];
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uc_mem_read(uc, STACK_BASE, obj->cc_blk->m_jmp.stack, STACK_SIZE);
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}
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if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp ||
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@ -267,9 +269,9 @@ bool emu_t::code_exec_callback(uc_engine* uc,
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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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free(obj->cc_trace.m_stack);
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obj->cc_trace.m_instrs.clear();
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}
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return true;
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@ -314,49 +316,51 @@ void emu_t::invalid_mem(uc_engine* uc,
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}
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}
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std::optional<std::pair<std::uintptr_t, std::uintptr_t>> emu_t::has_jcc(
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std::vector<vm::instrs::vinstr_t>& vinstrs) {
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if (vinstrs.back().mnemonic == vm::instrs::mnemonic_t::vmexit)
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return {};
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// number of LCONST virtual instructions which load 64bit imm's...
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const std::uint32_t lconst_num = std::accumulate(
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vinstrs.begin(), vinstrs.end(), 0,
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[&](std::uint32_t val, vm::instrs::vinstr_t& v) -> std::uint32_t {
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return v.mnemonic == vm::instrs::mnemonic_t::lconst && v.imm.size == 64
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? ++val
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: val;
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});
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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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bool emu_t::could_have_jcc(std::vector<vm::instrs::vinstr_t>& vinstrs) {
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// check to see if there is at least 3 LCONST %i64's
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if (std::accumulate(
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vinstrs.begin(), vinstrs.end(), 0u,
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[&](std::uint32_t val, vm::instrs::vinstr_t& v) -> std::uint32_t {
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return v.mnemonic == vm::instrs::mnemonic_t::lconst &&
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v.imm.size == 64
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? ++val
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: val;
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}) < 3)
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return false;
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// extract the lconst64's out of the virtual instruction stream...
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static const auto lconst64_chk = [&](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 lconst1 =
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std::find_if(vinstrs.rbegin(), vinstrs.rend(), lconst64_chk);
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if (lconst1 == vinstrs.rend())
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return false;
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const auto lconst2 = std::find_if(lconst1 + 1, vinstrs.rend(), lconst64_chk);
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if (lconst2 == vinstrs.rend())
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return false;
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// check to see if the imm val is inside of the image...
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if (lconst1->imm.val > m_vm->m_image_base + m_vm->m_image_size ||
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lconst1->imm.val < m_vm->m_image_base ||
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lconst2->imm.val > m_vm->m_image_base + m_vm->m_image_size ||
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lconst2->imm.val < m_vm->m_image_base)
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return false;
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// check to see if the imm's points to something inside of an executable
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// section...
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if (!vm::utils::scn::executable(
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m_vm->m_module_base,
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(lconst1->imm.val - m_vm->m_image_base) + m_vm->m_module_base) ||
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!vm::utils::scn::executable(
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m_vm->m_module_base,
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(lconst2->imm.val - m_vm->m_image_base) + m_vm->m_module_base))
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return false;
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return true;
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}
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} // namespace vm
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