to make an std::map<zydis_reg_t, unicorn_register>...main
John Doe
3 years ago
parent
79c3695828
commit
eb91191526
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#include <vminstrs.hpp>
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namespace vm::instrs {
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void deobfuscate(hndlr_trace_t& trace) {
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static const auto _uses_reg = [](zydis_decoded_operand_t& op,
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zydis_reg_t reg) -> bool {
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switch (op.type) {
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case ZYDIS_OPERAND_TYPE_MEMORY: {
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return vm::utils::reg::compare(op.mem.base, reg) ||
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vm::utils::reg::compare(op.mem.index, reg);
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}
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case ZYDIS_OPERAND_TYPE_REGISTER: {
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return vm::utils::reg::compare(op.reg.value, reg);
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}
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default:
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break;
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}
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return false;
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};
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static const auto _reads = [](zydis_decoded_instr_t& instr,
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zydis_reg_t reg) -> bool {
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if (instr.operands[0].type == ZYDIS_OPERAND_TYPE_MEMORY &&
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vm::utils::reg::compare(instr.operands[0].mem.base, reg))
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return true;
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for (auto op_idx = 0u; op_idx < instr.operand_count; ++op_idx)
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if (instr.operands[op_idx].actions & ZYDIS_OPERAND_ACTION_READ &&
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_uses_reg(instr.operands[op_idx], reg))
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return true;
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return false;
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};
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static const auto _writes = [](zydis_decoded_instr_t& instr,
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zydis_reg_t reg) -> bool {
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for (auto op_idx = 0u; op_idx < instr.operand_count; ++op_idx)
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// if instruction writes to the specific register...
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if (instr.operands[op_idx].type == ZYDIS_OPERAND_TYPE_REGISTER &&
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instr.operands[op_idx].actions & ZYDIS_OPERAND_ACTION_WRITE &&
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!(instr.operands[op_idx].actions & ZYDIS_OPERAND_ACTION_READ) &&
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vm::utils::reg::compare(instr.operands[op_idx].reg.value, reg))
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return true;
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return false;
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};
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std::uint32_t last_size = 0u;
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static const std::vector<ZydisMnemonic> blacklist = {
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ZYDIS_MNEMONIC_CLC, ZYDIS_MNEMONIC_BT, ZYDIS_MNEMONIC_TEST,
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ZYDIS_MNEMONIC_CMP, ZYDIS_MNEMONIC_CMC, ZYDIS_MNEMONIC_STC};
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static const std::vector<ZydisMnemonic> whitelist = {
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ZYDIS_MNEMONIC_PUSH, ZYDIS_MNEMONIC_POP, ZYDIS_MNEMONIC_CALL,
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ZYDIS_MNEMONIC_DIV};
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do {
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last_size = trace.m_instrs.size();
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for (auto itr = trace.m_instrs.begin(); itr != trace.m_instrs.end();
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++itr) {
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if (std::find(whitelist.begin(), whitelist.end(),
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itr->m_instr.mnemonic) != whitelist.end())
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continue;
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if (std::find(blacklist.begin(), blacklist.end(),
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itr->m_instr.mnemonic) != blacklist.end()) {
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trace.m_instrs.erase(itr);
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break;
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}
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if (vm::utils::is_jmp(itr->m_instr)) {
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trace.m_instrs.erase(itr);
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break;
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}
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zydis_reg_t reg = ZYDIS_REGISTER_NONE;
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// look for operands with writes to a register...
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for (auto op_idx = 0u; op_idx < itr->m_instr.operand_count; ++op_idx)
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if (itr->m_instr.operands[op_idx].type == ZYDIS_OPERAND_TYPE_REGISTER &&
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itr->m_instr.operands[op_idx].actions & ZYDIS_OPERAND_ACTION_WRITE)
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reg = vm::utils::reg::to64(itr->m_instr.operands[0].reg.value);
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// if this current instruction writes to a register, look ahead in the
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// instruction stream to see if it gets written too before it gets read...
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if (reg != ZYDIS_REGISTER_NONE) {
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// find the next place that this register is written too...
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auto write_result = std::find_if(itr + 1, trace.m_instrs.end(),
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[&](emu_instr_t& instr) -> bool {
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return _writes(instr.m_instr, reg);
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});
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auto read_result = std::find_if(itr + 1, write_result,
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[&](emu_instr_t& instr) -> bool {
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return _reads(instr.m_instr, reg);
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});
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// if there is neither a read or a write to this register in the
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// instruction stream then we are going to be safe and leave the
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// instruction in the stream...
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if (read_result == trace.m_instrs.end() &&
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write_result == trace.m_instrs.end())
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continue;
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// if there is no read of the register before the next write... and
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// there is a known next write, then remove the instruction from the
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// stream...
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if (read_result == write_result &&
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write_result != trace.m_instrs.end()) {
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// if the instruction reads and writes the same register than skip...
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if (_reads(read_result->m_instr, reg) &&
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_writes(read_result->m_instr, reg))
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continue;
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trace.m_instrs.erase(itr);
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break;
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}
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}
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}
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} while (last_size != trace.m_instrs.size());
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}
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void init() {
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if (static std::atomic_bool once = true; once.exchange(false))
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std::sort(profiles.begin(), profiles.end(),
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[&](profiler_t* a, profiler_t* b) -> bool {
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return a->matchers.size() > b->matchers.size();
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});
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}
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vinstr_t determine(zydis_reg_t& vip, zydis_reg_t& vsp, hndlr_trace_t& hndlr) {
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const auto& instrs = hndlr.m_instrs;
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const auto profile = std::find_if(
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profiles.begin(), profiles.end(), [&](profiler_t* profile) -> bool {
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for (auto& matcher : profile->matchers) {
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const auto matched =
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std::find_if(instrs.begin(), instrs.end(),
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[&](const emu_instr_t& instr) -> bool {
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const auto& i = instr.m_instr;
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return matcher(vip, vsp, i);
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});
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if (matched == instrs.end())
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return false;
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}
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return true;
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});
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if (profile == profiles.end())
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return vinstr_t{mnemonic_t::unknown};
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auto result = (*profile)->generate(vip, vsp, hndlr);
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return result.has_value() ? result.value() : vinstr_t{mnemonic_t::unknown};
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}
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profiler_t* get_profile(mnemonic_t mnemonic) {
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if (mnemonic == mnemonic_t::unknown)
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return nullptr;
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const auto res = std::find_if(profiles.begin(), profiles.end(),
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[&](profiler_t* profile) -> bool {
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return profile->mnemonic == mnemonic;
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});
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return res == profiles.end() ? nullptr : *res;
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}
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} // namespace vm::instrs
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