Hardware Breakpoint 까지 소스

my_debugger.py

my_test_hw.py

이 이외의 소스는 변경되지 않았기에, 업로드 하지 않았다. (my_debugger_defines.py , printf_loop 등)

my_debugger.py

# -*- coding: cp949 -*-
from ctypes import *
from my_debugger_defines import *

kernel32 = windll.kernel32

class debugger():

    def __init__(self):
        self.h_process       =     None
        self.pid             =     None
        self.debugger_active =     False
        self.h_thread        =     None
        self.context         =     None
        self.exception       =     None
        self.exception_address  =   None
        self.breakpoints    = {} 
        self.first_breakpoint = True
        self.hardware_breakpoints = {}

        # Here let's determine and store 
        # the default page size for the system
        # determine the system page size.

        
              
                
    def load(self,path_to_exe):
        
        # dwCreation flag determines how to create the process
        # set creation_flags = CREATE_NEW_CONSOLE if you want
        # to see the calculator GUI
        creation_flags = DEBUG_PROCESS
    
        # instantiate the structs
        startupinfo         = STARTUPINFO()
        process_information = PROCESS_INFORMATION()
        
        # The following two options allow the started process
        # to be shown as a separate window. This also illustrates
        # how different settings in the STARTUPINFO struct can affect
        # the debuggee.
        startupinfo.dwFlags     = 0x1
        startupinfo.wShowWindow = 0x0
        
        # We then initialize the cb variable in the STARTUPINFO struct
        # which is just the size of the struct itself
        startupinfo.cb = sizeof(startupinfo)
        
        if kernel32.CreateProcessA(path_to_exe,
                                   None,
                                   None,
                                   None,
                                   None,
                                   creation_flags,
                                   None,
                                   None,
                                   byref(startupinfo),
                                   byref(process_information)):
            
            print "[*] We have successfully launched the process!"
            print "[*] PID : %d" % process_information.dwProcessId
            
            # 새로 생성한 프로세스의 핸들을 구한 후
            # 나중에 접근하기 위해 저장한다.
            self.h_process = self.open_process(process_information.dwProcessId)

        else:    
            print "[*] Error : 0x%08x." % kernel32.GetLastError()


    def open_process(self,pid):
        
        # PROCESS_ALL_ACCESS = 0x0x001F0FFF
        h_process = kernel32.OpenProcess(PROCESS_ALL_ACCESS,False,pid) 
        return h_process
    
    
    def open_thread(self, thread_id):   # thread_id를 인자로 전달해주면 해당 thread의 핸들을 리턴한다.
        h_thread = kernel32.OpenThread(THREAD_ALL_ACCESS, None, thread_id)
        
        if h_thread is not None:
            return h_thread
        else:
            print "[*] Could not obtain a valid thread handle."
            return False
        
        
    def enumerate_threads(self):
        thread_entry = THREADENTRY32()    # Thread32First 실행인자로 전달되는 구조체
        thread_list = []
        snapshot = kernel32.CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, self.pid)
            
        if snapshot is not None:
            # 먼저 구조체의 크기를 설정해야 한다.
            thread_entry.dwSize = sizeof(thread_entry)
            success = kernel32.Thread32First(snapshot, byref(thread_entry))
            
            while success:
                if thread_entry.th32OwnerProcessID == self.pid:
                    thread_list.append(thread_entry.th32ThreadID)
                    
                success = kernel32.Thread32Next(snapshot, byref(thread_entry))
                # Thread32First 함수 실행 후에는 Thread32Next 함수로 스레드 리스트를 끝까지 열거한다.
                
            kernel32.CloseHandle(snapshot)
            return thread_list
        else:
            return False
        
            
    def get_thread_context (self, thread_id=None, h_thread=None):
        context = CONTEXT()     # 디버그 레지스터에 대한 정보를 담고있는 CONTEXT 구조체이다.
        context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS
        
        # 스레드의 핸들을 구한다.
        if h_thread is None:
            self.h_thread = self.open_thread(thread_id)
        if kernel32.GetThreadContext(self.h_thread, byref(context)):
            # 레지스터 정보를 얻기 위해서 GetThreadContext 함수를 사용한다.
            # 첫 인자는 레지스터를 얻고자 하는 스레드의 핸들이며, 두번째는 정보가 저장되어야 하는 context의 포인터이다.
            return context
        else:
            return False
        
        
    def attach(self,pid):
        
        self.h_process = self.open_process(pid)
        
        # 프로세스에 대한 어태치를 시도한다.
        # 실패하면 호출을 종료한다.
        if kernel32.DebugActiveProcess(pid):
            self.debugger_active = True
            self.pid             = int(pid)
                                  
        else:
            print "[*] Unable to attach to the process."
            
            
    def run(self):
        
        # 이제 디버기에 대한 디버그 이벤트를 처리해야 한다. 
        # debugging events           
        while self.debugger_active == True:
            self.get_debug_event() 
            
    
    def get_debug_event(self):
        resultMap = {
            1:"EXCEPTION_DEBUG_EVENT",
            2:"CREATE_THREAD_DEBUG_EVENT",
            3:"CREATE_PROCESS_DEBUG_EVENT",
            4:"EXIT_THREAD_DEBUG_EVENT",
            5:"EXIT_PROCESS_DEBUG_EVENT",
            6:"LOAD_DLL_DEBUG_EVENT",
            7:"UNLOAD_DLL_DEBUG_EVENT",
            8:"OUTPUT_DEBUG_STRING_EVENT",
            9:"RIP_EVENT"
        }
        
        debug_event     = DEBUG_EVENT()
        continue_status = DBG_CONTINUE
        
        if kernel32.WaitForDebugEvent(byref(debug_event), 100):
            
            # 스레드의 컨텍스터 정보를 구한다.
            self.h_thread = self.open_thread(debug_event.dwThreadId)
            self.context = self.get_thread_context(h_thread = self.h_thread)
            self.debug_event = debug_event
            print "Event Code: %d : %s / Thread Id: %d" % (debug_event.dwDebugEventCode,resultMap.get(debug_event.dwDebugEventCode), debug_event.dwThreadId)
            
            if debug_event.dwDebugEventCode == EXCEPTION_DEBUG_EVENT:
                self.exception = debug_event.u.Exception.ExceptionRecord.ExceptionCode
                self.exception_address = debug_event.u.Exception.ExceptionRecord.ExceptionAddress

                if self.exception == EXCEPTION_ACCESS_VIOLATION:
                    print "Access Violation Detected."

                elif self.exception == EXCEPTION_BREAKPOINT:
                    continue_status = self.exception_handler_breakpoint()
                
                elif self.exception == EXCEPTION_GUARD_PAGE:
                    print "Guard Page Access Detected."
                
                elif self.exception == EXCEPTION_SINGLE_STEP:
                    print "Single Stepping."
                    self.exception_handler_single_step()
                

            kernel32.ContinueDebugEvent(
                    debug_event.dwProcessId,
                    debug_event.dwThreadId,
                    continue_status)
            
            
    def detach(self):
        
        if kernel32.DebugActiveProcessStop(self.pid):
            print "[*] Finished debugging. Exiting..."
            return True
        else:
            print "There was an error"
            return False

    def exception_handler_breakpoint(self):
        #print "[+] Inside the breakpoint handler."
        print "Exception Address: 0x%08x" % self.exception_address
        if not self.breakpoints.has_key(self.exception_address):
            if self.first_breakpoint == True:
                self.first_breakpoint = False
                print "[+] Hit the first breakpoint."
                return DBG_CONTINUE
        else:
            print "[+] Hit user defined breakpoint."
            self.write_process_memory(self.exception_address,self.breakpoints[self.exception_address])
            self.context = self.get_thread_context(h_thread=self.h_thread)
            self.context.Eip -= 0x01 # Error!
            kernel32.SetThreadContext(self.h_thread,byref(self.context))
            continue_status = DBG_CONTINUE

        return continue_status

    def read_process_memory(self,address,length):
        data    = ""
        read_buf    = create_string_buffer(length)
        count   = c_ulong(0)

        if not kernel32.ReadProcessMemory(self.h_process,address,read_buf,length,byref(count)):
            return False

        else:
            data = data + read_buf.raw
            return data
    def write_process_memory(self,address,data):
        count = c_ulong(0)
        length = len(data)

        c_data = c_char_p(data[count.value:])

        if not kernel32.WriteProcessMemory(self.h_process,address,c_data,length,byref(count)):
            return False

        else:
            return True
    def bp_set(self,address):
        if not self.breakpoints.has_key(address):
            try:
                #원래의 바이트 값을 저장
                original_byte = self.read_process_memory(address,1)
            
                # cc opcode write
                self.write_process_memory(address,"\xCC")

                # 리스트에 bp 추가
                self.breakpoints[address] = (original_byte)
                print self.breakpoints[address]
            except:
                return False
            return True
    

    def resolve_func(self,dll,function):
        handle = kernel32.GetModuleHandleA(dll)
        address = kernel32.GetProcAddress(handle,function)

        kernel32.CloseHandle(handle)

        return address

    def bp_set_hw(self,address,length,condition):
        # check length value
        if length not in (1,2,4):
            return False
        else:
            length -= 1

        # check condition value
        if condition not in (HW_ACCESS,HW_EXECUTE,HW_WRITE):
            return False

        # check Debug register 
        if not self.hardware_breakpoints.has_key(0):
            available = 0
        elif not self.hardware_breakpoints.has_key(1):
            available = 1
        elif not self.hardware_breakpoints.has_key(2):
            available = 2
        elif not self.hardware_breakpoints.has_key(3):
            available = 3
        else:
            return False

        # configure Debug Register at whole thread
        for thread_id in self.enumerate_threads():
            context = self.get_thread_context(thread_id = thread_id)

            # 어느 디버그 레지스터를 이용해 브레이크포인트를 설정할 것인지
            # DR7 레지스터의 플래그 값을 설정함.
            context.Dr7 |= 1 << (available * 2) 

            # 브레이크 포인트를 설정할 주소를 유효한 디버그 레지스터에 저장한다.
            if available == 0:
                context.Dr0 = address
            elif available == 1:
                context.Dr1 = address
            elif available == 2:
                context.Dr2 = address
            elif available == 3:
                context.Dr3 = address

            # 브레이크 포인트 조건 플래그 설정.
            context.Dr7 |= condition << ((available * 4) + 16)

            # set length
            context.Dr7 |= length << ((available * 4) + 18)

            # 브레이크 포인트가 설정된 쓰레드 컨텍스트를 설정
            h_thread = self.open_thread(thread_id)
            kernel32.SetThreadContext(h_thread,byref(context))

            # 내부적으로 관리하는 하드웨어 브레이크포인트 배열을 갱신한다.
            self.hardware_breakpoints[available] = (address,length,condition)
        return True


    def exception_handler_single_step(self):
        if self.context.Dr6 & 0x1 and self.hardware_breakpoints.has_key(0):
            slot = 0
        elif self.context.Dr6 & 0x2 and self.hardware_breakpoints.has_key(1):
            slot = 1
        elif self.context.Dr6 & 0x4 and self.hardware_breakpoints.has_key(2):
            slot = 2
        elif self.context.Dr6 & 0x8 and self.hardware_breakpoints.has_key(3):
            slot = 3
        else:
            # 하드웨어 브레이크 포인트에 의해 발생한 INT 1 
            continue_status = DBG_EXCEPTION_NOT_HANDLED
        
        # 이제는 리스트에서 브레이크 포인트를 제거하자
        if self.bp_del_hw(slot):
            continue_status = DBG_CONTINUE

        print "[+] Hardware breakpoint removed."
        return continue_status

    def bp_del_hw(self,slot):
        # 동작 중인 모든 쓰레드의 하드웨어 브레이크 포인트를 제거한다.
        for thread_id in self.enumerate_threads():
            context = self.get_thread_context(thread_id = thread_id)

            # 하드웨어 브레이크 포인트를 제거하기 위해 Dr7 레지스터 플래그 초기화
            context.Dr7 &= ~(1 << (slot * 2))

            # 브레이크 포인트 주소를 제거
            if slot == 0:
                context.Dr0 = 0x00000000
            elif slot == 1:
                context.Dr1 = 0x00000000
            elif slot == 2:
                context.Dr2 = 0x00000000
            elif slot == 3:
                context.Dr3 = 0x00000000

            # 브레이크 포인트 조건 플래그 리셋
            context.Dr7 &= ~(3 << ((slot * 4) + 16))
            
            # 길이 플래그 리셋
            context.Dr7 &= ~(3 << ((slot * 4) + 18))

            # 브레이크 포인트가 제거된 쓰레드 컨텍스트로 설정
            h_thread = self.open_thread(thread_id)
            kernel32.SetThreadContext(h_thread,byref(context))


        # 내부 리스트에서 해당 브레이크 포인트를 제거
        del self.hardware_breakpoints[slot]
        return True

my_test_hw.py

# -*- coding: cp949 -*-
import my_debugger
from my_debugger_defines import *


f=open("pid.txt",'r')
pid=f.readline()

debugger = my_debugger.debugger()

printf_address = debugger.resolve_func("msvcrt.dll","printf")
debugger.attach(int(pid))

print "pid : %s" % pid
print "[+] Address of printf : 0x%08x" % printf_address

#change
debugger.bp_set_hw(printf_address,1,HW_EXECUTE)


debugger.run()
debugger.detach()