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vmemu
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this code sucks so fucking bad, i need to recode everything, its dog

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shit:
master
_xeroxz 3 years ago
parent e086bf0377
commit 32b90cdccc
2 changed files with 95 additions and 29 deletions
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6
include/vmemu_t.hpp
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@ -125,5 +125,11 @@ class emu_t {
/// <param name="branch_addr"></param>
/// <returns></returns>
bool legit_branch(vm::instrs::vblk_t& vblk, std::uintptr_t branch_addr);
void emulate_branch(uc_context* ctx,
std::uint8_t* stack,
std::uintptr_t branch_addr,
zydis_reg_t vsp,
vm::instrs::vblk_t& vblk);
};
} // namespace vm

118
src/vmemu_t.cpp
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@ -112,13 +112,58 @@ bool emu_t::emulate(std::uint32_t vmenter_rva, vm::instrs::vrtn_t& vrtn) {
blk.branch_type = vm::instrs::vbranch_type::jcc;
std::printf("> code block has jcc, b1 = %p, b2 = %p\n", b1, b2);
} else {
uc_context* backup;
std::uint8_t* stack = new std::uint8_t[STACK_SIZE];
uc_mem_read(uc, STACK_BASE, stack, STACK_SIZE);
uc_context_alloc(uc, &backup);
uc_context_save(uc, backup);
uc_context_restore(uc, blk.m_jmp.ctx);
std::uintptr_t vsp_ptr = 0ull, branch_addr = 0ull;
uc_reg_read(uc, vm::instrs::reg_map[blk.m_vm.vsp], &vsp_ptr);
uc_mem_read(uc, vsp_ptr, &branch_addr, sizeof branch_addr);
uc_context_restore(uc, backup);
uc_context_free(backup);
uc_mem_write(uc, STACK_BASE, stack, STACK_SIZE);
delete stack;
blk.branches.push_back(branch_addr);
blk.branch_type = vm::instrs::vbranch_type::absolute;
std::printf("> code block has absolute jmp...\n");
std::printf("> code block has absolute jmp, b1 = %p\n", branch_addr);
}
}
return true;
}
void emu_t::emulate_branch(uc_context* ctx,
std::uint8_t* stack,
std::uintptr_t branch_addr,
zydis_reg_t vsp,
vm::instrs::vblk_t& vblk) {
uc_context* backup;
std::uint8_t* stack_backup = new std::uint8_t[STACK_SIZE];
std::uintptr_t vsp_addr = 0ull, rip = 0ull;
uc_context_alloc(uc, &backup);
uc_context_save(uc, backup);
uc_mem_read(uc, STACK_BASE, stack_backup, STACK_SIZE);
uc_context_restore(uc, ctx);
uc_mem_write(uc, STACK_BASE, stack, STACK_SIZE);
uc_reg_read(uc, vm::instrs::reg_map[vsp], &vsp_addr);
uc_reg_read(uc, UC_X86_REG_RIP, &rip);
uc_mem_write(uc, vsp_addr, &branch_addr, sizeof branch_addr);
cc_blk = &vblk;
uc_emu_start(uc, rip, 0u, 0u, 0u);
uc_mem_write(uc, STACK_BASE, stack_backup, STACK_SIZE);
uc_context_restore(uc, backup);
uc_context_free(backup);
delete stack_backup;
}
void emu_t::int_callback(uc_engine* uc, std::uint32_t intno, emu_t* obj) {
uc_err err;
std::uintptr_t rip = 0ull;
@ -342,36 +387,38 @@ bool emu_t::code_exec_callback(uc_engine* uc,
std::getchar();
}
if (obj->cc_blk->m_vinstrs.size()) {
if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp) {
uc_context *backup, *copy;
// backup current unicorn-engine context...
uc_context_alloc(uc, &backup);
uc_context_alloc(uc, &copy);
uc_context_save(uc, backup);
// make a copy of the first cpu context of the jmp handler...
uc_context_restore(uc, obj->cc_trace.m_instrs.begin()->m_cpu);
uc_context_save(uc, copy);
// restore the unicorn-engine context... also free the backup...
uc_context_restore(uc, backup);
uc_context_free(backup);
// set current code block virtual jmp instruction information...
obj->cc_blk->m_jmp.ctx = copy;
obj->cc_blk->m_jmp.stack = new std::uint8_t[STACK_SIZE];
std::memcpy(obj->cc_blk->m_jmp.stack, obj->cc_trace.m_stack,
STACK_SIZE);
}
if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp ||
vinstr.mnemonic == vm::instrs::mnemonic_t::vmexit)
uc_emu_stop(obj->uc);
}
obj->cc_trace.m_vip = obj->vip;
obj->cc_trace.m_vsp = obj->vsp;
obj->cc_blk->m_vinstrs.push_back(vinstr);
if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp) {
uc_context *backup, *copy;
// backup current unicorn-engine context...
uc_context_alloc(uc, &backup);
uc_context_alloc(uc, &copy);
uc_context_save(uc, backup);
// make a copy of the first cpu context of the jmp handler...
uc_context_restore(uc, obj->cc_trace.m_instrs.begin()->m_cpu);
uc_context_save(uc, copy);
// restore the unicorn-engine context... also free the backup...
uc_context_restore(uc, backup);
uc_context_free(backup);
// set current code block virtual jmp instruction information...
obj->cc_blk->m_jmp.ctx = copy;
obj->cc_blk->m_jmp.stack = new std::uint8_t[STACK_SIZE];
std::memcpy(obj->cc_blk->m_jmp.stack, obj->cc_trace.m_stack,
STACK_SIZE);
}
if (vinstr.mnemonic == vm::instrs::mnemonic_t::jmp ||
vinstr.mnemonic == vm::instrs::mnemonic_t::vmexit)
uc_emu_stop(obj->uc);
}
// -- free the trace since we will start a new one...
@ -434,7 +481,14 @@ bool emu_t::legit_branch(vm::instrs::vblk_t& vblk, std::uintptr_t branch_addr) {
(void*)&vm::emu_t::branch_pred_spec_exec, this,
m_vm->m_module_base, m_vm->m_module_base + m_vm->m_image_size);
// restore cpu and stack...
// -- make a backup of the current emulation state...
uc_context* backup;
uc_context_alloc(uc, &backup);
uc_context_save(uc, backup);
std::uint8_t* stack = new std::uint8_t[STACK_SIZE];
uc_mem_read(uc, STACK_BASE, stack, STACK_SIZE);
// restore cpu and stack back to the virtual jump handler...
uc_context_restore(uc, vblk.m_jmp.ctx);
uc_mem_write(uc, STACK_BASE, vblk.m_jmp.stack, STACK_SIZE);
@ -446,6 +500,12 @@ bool emu_t::legit_branch(vm::instrs::vblk_t& vblk, std::uintptr_t branch_addr) {
m_sreg_cnt = 0u;
uc_emu_start(uc, rip, 0ull, 0ull, 0ull);
// -- restore original cpu and stack...
uc_mem_write(uc, STACK_BASE, stack, STACK_SIZE);
uc_context_restore(uc, backup);
uc_context_free(backup);
delete stack;
// add normal execution callback back...
uc_hook_add(uc, &code_exec_hook, UC_HOOK_CODE,
(void*)&vm::emu_t::code_exec_callback, this, m_vm->m_module_base,

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