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thread.cpp
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thread.cpp
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/*
*
* Copyright (C) 2010-2011 Amr Thabet <amr.thabet@student.alx.edu.eg>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to Amr Thabet
* amr.thabet@student.alx.edu.eg
*
*/
#include "x86emu.h"
#ifdef WIN32
#include "windows.h"
#endif
bool is_negative(DWORD num, DWORD ins_flags);
char PF_Flags[256] = {
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
0, 1, 1, 0, 1, 0, 0, 1,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
1, 0, 0, 1, 0, 1, 1, 0,
};
Thread::Thread() {
// this for the parser as we don't need anything from the thread just work in pointers
}
Process * Thread::GetProcess() {
return process;
}
Thread::Thread(DWORD neip, Process & s) {
// initialize the thread
process = &s;
// create the stack
// it's created from tests only and I didn't use the Heap Commit & Reserve
// I use Size = 0xA000
seh_enable = true;
#ifdef WIN32
DWORD x = (DWORD) VirtualAlloc(NULL, 0xA000, MEM_COMMIT, PAGE_READWRITE); // the virtual place
#else
DWORD x = (DWORD) malloc(0xA000); // the virtual place
#endif
memset((void *) x, 0, 0xA000);
stack = new Stack(*this);
mem = process->SharedMem;
DWORD StackAddr = mem->create_memory_address(VMEM_TYPE_STACK);
mem->add_pointer(x, StackAddr, 0xA000);
Exx[4] = StackAddr + 0x9F90; // esp
Exx[5] = StackAddr + 0x9F94; // ebp
// preparing the TIB,TEB
CreateTEB();
still_tls = false;
if (process->AppType != PROCESS_SHELLCODE)
{
DWORD image = (DWORD) s.SharedMem->read_virtual_mem(s.GetImagebase());
DWORD PEHeader_ptr = ((dos_header *) image)->e_lfanew + image;
image_header * PEHeader = (image_header *) PEHeader_ptr;
if (PEHeader->optional.data_directory[IMAGE_DIRECTORY_ENTRY_TLS].virtual_address != 0) {
_IMAGE_TLS_DIRECTORY * tlsheader = (_IMAGE_TLS_DIRECTORY *) ((DWORD) PEHeader->optional.data_directory[IMAGE_DIRECTORY_ENTRY_TLS].virtual_address + image);
if (tlsheader->AddressOfCallBacks != 0) {
DWORD * callbacks = s.SharedMem->read_virtual_mem((DWORD) tlsheader->AddressOfCallBacks);
if (callbacks[0] != 0) {
stack->push(0);
stack->push(1);
stack->push(0);
stack->push(TLS_MAGIC);
this->Eip = callbacks[0];
log = new Log(this->Eip);
still_tls = true;
tls_callback_index++;
}
}
}
}
entry_point = neip;
if (still_tls == false) {
this->Eip = neip;
log = new Log(neip);
if (process->IsDLL) {
stack->push(0);
stack->push(1);
stack->push(process->GetImagebase());
}
stack->push(mem->get_virtual_pointer(process->getsystem()->APITable[0].addr)); // pushes the pointer to ExitProcess (some viruses get the kernelbase from it
}
// preparing FPU
SelectedReg = 0;
for (int i = 0; i < 8; i++)
{
ST[i] = 0;
}
}
void Thread::updateflags(DWORD dest, DWORD src, DWORD result, int flags, DWORD ins_flags) {
bool CF = false; // reserve The CF
if ((EFlags & EFLG_CF) && (flags != UPDATEFLAGS_ADD) && (flags != UPDATEFLAGS_SUB)) {
CF = true; // save the CF before being deleted
}
this->EFlags = EFLG_SYS;
// --------------------------------------------------
// ZF & SF & OF
if (result == 0) {
EFlags |= EFLG_ZF; // zero
}
if (is_negative(result, ins_flags)) {
EFlags |= EFLG_SF; // negative
}
if ((flags == UPDATEFLAGS_ADD) && (is_negative(dest, ins_flags) == false) && (is_negative(result, ins_flags) == true)) {
EFlags |= EFLG_OF; // From Positive to Negative
}
if ((flags == UPDATEFLAGS_SUB) && (is_negative(dest, ins_flags) == false) && (is_negative(src, ins_flags) == true) && (is_negative(result, ins_flags) == true)) {
EFlags |= EFLG_OF; // from positive to negative
}
// --------------------------------------------------
// CF & AF
if ((flags == UPDATEFLAGS_ADD) && (dest > result)) {
EFlags |= EFLG_CF | EFLG_AF; // overflow of positive
}
if ((flags == UPDATEFLAGS_SUB) && (result > dest)) {
EFlags |= EFLG_CF | EFLG_AF; // overflow of negative
}
// -------------------------------------------------
// PF
char PFindex = result & 0xFF;
if (PF_Flags[PFindex] == 1) {
EFlags |= EFLG_PF;
}
if (CF) {
EFlags |= EFLG_CF; // restore CF
}
}
// This function determines if this number is positive or negative based on the operand size
bool is_negative(DWORD num, DWORD ins_flags) {
if (ins_flags & DEST_BITS8) {
if (num & 0x80) {
return true;
} else {
return false;
}
} else if (ins_flags & DEST_BITS16) {
if (num & 0x8000) {
return true;
} else {
return false;
}
} else {
if (num & 0x80000000) {
return true;
} else {
return false;
}
}
return false;
}
void Thread::FpuUpdateFlags( DISASM_INSTRUCTION * s)
{
FpuEnv.LastInstructionPointer = Eip - s->hde.len;
FpuEnv.LastOpcode = (s->hde.opcode - 0xD8) << 8 + s->hde.modrm;
}
void Thread::CreateTEB() {
#ifdef WIN32
tib = (TIB *) VirtualAlloc(NULL, sizeof(TEB) + sizeof(TIB), MEM_COMMIT, PAGE_READWRITE); // the virtual place
#else
tib = (TIB *) malloc(sizeof(TEB) + sizeof(TIB)); // the virtual place
#endif
memset(tib, 0, sizeof(TEB) + sizeof(TIB));
teb = (TEB *) ((DWORD) tib + (DWORD) sizeof(TIB));
tib->ExceptionList = (_PEXCEPTION_REGISTRATION_RECORD *) 0x0012FFC4;
int n = 0xFFFFFFFF; // End of SEH Chain
mem->write_virtual_mem((DWORD) tib->ExceptionList, (DWORD) 4, (unsigned char *) &n);
mem->write_virtual_mem((DWORD) (tib->ExceptionList + 4), (DWORD) 4, (unsigned char *) &n);
tib->TIBOffset = 0x7FFDF000; // pointer to SEH Chain
teb->Peb = (PEB *) 0x7FFD5000;
this->fs = 0x7FFDF000; // set the fs segment to this place
mem->add_pointer((DWORD) tib, 0x7FFDF000, sizeof(TEB) + sizeof(TIB));
DWORD ptr = *mem->read_virtual_mem(GetFS());
}
DWORD Thread::GetFS() {
return fs;
}
void Thread::TLSContinue() {
if (still_tls) {
DWORD image = (DWORD) mem->read_virtual_mem(process->GetImagebase());
DWORD PEHeader_ptr = ((dos_header *) image)->e_lfanew + image;
image_header * PEHeader = (image_header *) PEHeader_ptr;
_IMAGE_TLS_DIRECTORY * tlsheader = (_IMAGE_TLS_DIRECTORY *) ((DWORD) PEHeader->optional.data_directory[IMAGE_DIRECTORY_ENTRY_TLS].virtual_address + image);
DWORD * callbacks = mem->read_virtual_mem((DWORD) tlsheader->AddressOfCallBacks);
if (callbacks[tls_callback_index] != 0) {
stack->push(0);
stack->push(1);
stack->push(0);
stack->push(TLS_MAGIC);
this->Eip = callbacks[tls_callback_index];
log = new Log(this->Eip);
still_tls = true;
tls_callback_index++;
} else {
still_tls = false;
this->Eip = entry_point;
log = new Log(entry_point);
}
}
}