beginning to look a lot like christmas...

main
John Doe 3 years ago
parent 1f527e400f
commit 1e6ae7b78c

2
deps/vmprofiler vendored

@ -1 +1 @@
Subproject commit 11650b6d8aa319940a298f707645334898f8de5d
Subproject commit 20ad0b595078ebf82d977ddfb5999332b2ce0e73

@ -16,10 +16,12 @@ class emu_t {
~emu_t();
bool init();
void emulate();
private:
uc_engine* uc_ctx;
const vm::vmctx_t* m_vm_ctx;
zydis_reg_t vip, vsp;
uc_hook code_exec_hook, invalid_mem_hook, int_hook;
static void int_callback(uc_engine* uc, std::uint32_t intno, emu_t* obj);

@ -134,5 +134,6 @@ int __cdecl main(int argc, const char* argv[]) {
"reason...\n");
return -1;
}
emu.emulate();
}
}

@ -1,7 +1,8 @@
#include <vmemu_t.hpp>
namespace vm {
emu_t::emu_t(vm::vmctx_t* vm_ctx) : m_vm_ctx(vm_ctx) {}
emu_t::emu_t(vm::vmctx_t* vm_ctx)
: m_vm_ctx(vm_ctx), vip(vm_ctx->get_vip()), vsp(vm_ctx->get_vsp()) {}
emu_t::~emu_t() {
if (uc_ctx)
@ -58,6 +59,28 @@ bool emu_t::init() {
return true;
}
void emu_t::emulate() {
uc_err err;
std::uintptr_t rip = m_vm_ctx->m_vm_entry_rva + m_vm_ctx->m_module_base,
rsp = STACK_BASE + STACK_SIZE - PAGE_4KB;
if ((err = uc_reg_write(uc_ctx, UC_X86_REG_RSP, &rsp))) {
std::printf("> uc_reg_write error, reason = %d\n", err);
return;
}
if ((err = uc_reg_write(uc_ctx, UC_X86_REG_RIP, &rip))) {
std::printf("> uc_reg_write error, reason = %d\n", err);
return;
}
std::printf("> beginning execution at = %p\n", rip);
if ((err = uc_emu_start(uc_ctx, rip, 0ull, 0ull, 0ull))) {
std::printf("> error starting emu... reason = %d\n", err);
return;
}
}
void emu_t::int_callback(uc_engine* uc, std::uint32_t intno, emu_t* obj) {
uc_err err;
std::uintptr_t rip = 0ull;
@ -93,6 +116,54 @@ bool emu_t::code_exec_callback(uc_engine* uc,
uint64_t address,
uint32_t size,
emu_t* obj) {
uc_err err;
static thread_local zydis_decoded_instr_t instr;
static thread_local zydis_rtn_t instr_stream;
if (!ZYAN_SUCCESS(ZydisDecoderDecodeBuffer(vm::utils::g_decoder.get(),
reinterpret_cast<void*>(address),
PAGE_4KB, &instr))) {
std::printf("> failed to decode instruction at = 0x%p\n", address);
if ((err = uc_emu_stop(uc))) {
std::printf("> failed to stop emulation, exiting... reason = %d\n", err);
exit(0);
}
return false;
}
if (instr.mnemonic == ZYDIS_MNEMONIC_INVALID)
return false;
instr_stream.push_back({instr});
if (instr.mnemonic == ZYDIS_MNEMONIC_RET ||
(instr.mnemonic == ZYDIS_MNEMONIC_JMP &&
instr.operands[0].type == ZYDIS_OPERAND_TYPE_REGISTER)) {
// find the last mov reg, [vip]
auto fetch_offset = std::find_if(
instr_stream.rbegin(), instr_stream.rend(),
[&](const zydis_instr_t& instr) -> bool {
return instr.instr.mnemonic == ZYDIS_MNEMONIC_MOV &&
instr.instr.operands[0].type == ZYDIS_OPERAND_TYPE_REGISTER &&
instr.instr.operands[1].type == ZYDIS_OPERAND_TYPE_MEMORY &&
instr.instr.operands[1].mem.base == obj->m_vm_ctx->get_vip();
});
// cut off the extra stuff...
if (fetch_offset != instr_stream.rend())
instr_stream.erase((fetch_offset + 1).base(), instr_stream.end());
vm::utils::deobfuscate(instr_stream);
vm::utils::print(instr_stream);
auto vinstr = vm::instrs::determine(obj->vip, obj->vsp, instr_stream);
if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp) {
std::printf("> found jmp...\n");
std::getchar();
}
instr_stream.clear();
std::printf("============\n");
}
return true;
}

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