Windows环境下的调试器探究

2022-04-27 10:29:56 浏览数 (2)

软件断点

当在调试器下一个断点,其实就是把这行汇编语句的硬编码改为CC,即int 3

被调试进程

1.CPU检测到INT 3指令 2.查IDT表找到对应的函数 3.CommonDispatchException 4.KiDispatchException 5.DbgkForwardException收集并发送调试事件

首先找到IDT表的3号中断

调用CommonDispatchException

通过KiDispatchException分发异常

首先用KeContextFromframes备份,若为用户调用则跳转

进入函数如果没有内核调试器则跳转,也就是说如果有内核调试器的存在,3环调试器是接收不到异常的

然后调用调试事件

DbgkForwardException主要是通过DbgkpSendApiMessage来发送调试事件,第二个参数决定线程是否挂起,首先通过cmp判断,如果为0则直接跳转,如果不为0则调用DbgkpSuspendProcess将被调试进程挂起

也就是说如果要想调试进程,就必须要调用DbgkpSuspendProcess将调试进程挂起

首先用调试模式创建进程,然后使用调试循环

如果是异常事件则调用ExceptionHandler

ExceptionHandler主要是通过判断ExcptionRecord结构里面的ExceptionCode来判断异常的类型,然后调用相应的函数,这里首先看软件断点,即int 3,调用Int3ExceptionProc

下断点会把之前的指令修改为CC,如果不是系统断点,就把下断点的位置修改的指令写回去,然后获取int3断点的地址

然后获取上下文,所有调试寄存器都存储在ContextFlags里面

当我们下软件断点的时候,EIP并不会停留在断点的地方,而是会停留在断点 1的地方(这里不同的异常EIP停留的位置不同),所以这里需要进行EIP-1的操作

然后调用处理的函数

当被调试进程收集并发送调试事件之后就会处于阻塞状态,根据异常处理的结果决定下一步的执行

实现代码如下

// Debug4.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <stdio.h> #include <windows.h> #include <tlhelp32.h> #define DEBUGGEE "C:\ipmsg.exe" //被调试进程ID,进程句柄,OEP DWORD dwDebuggeePID = 0; //被调试线程句柄 HANDLE hDebuggeeThread = NULL; HANDLE hDebuggeeProcess = NULL; //系统断点 BOOL bIsSystemInt3 = TRUE; //被INT 3覆盖的数据 CHAR OriginalCode = 0; //线程上下文 CONTEXT Context; typedef HANDLE (__stdcall *FnOpenThread) (DWORD, BOOL, DWORD); VOID InitDebuggeeInfo(DWORD dwPID, HANDLE hProcess) { dwDebuggeePID = dwPID; hDebuggeeProcess = hProcess; } DWORD GetProcessId(LPTSTR lpProcessName) { HANDLE hProcessSnap = NULL; PROCESSENTRY32 pe32 = {0}; hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); if(hProcessSnap == (HANDLE)-1) { return 0; } pe32.dwSize = sizeof(PROCESSENTRY32); if(Process32First(hProcessSnap, &pe32)) { do { if(!strcmp(lpProcessName, pe32.szExeFile)) return (int)pe32.th32ProcessID; } while (Process32Next(hProcessSnap, &pe32)); } else { CloseHandle(hProcessSnap); } return 0; } BOOL WaitForUserCommand() { BOOL bRet = FALSE; CHAR command; printf("COMMAND > "); command = getchar(); switch(command) { // into case 't': bRet = TRUE; break; // pass case 'p': bRet = TRUE; break; // go case 'g': bRet = TRUE; break; } getchar(); return bRet; } BOOL Int3ExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; //1. 将INT 3修复为原来的数据(如果是系统断点,不用修复) if(bIsSystemInt3) { bIsSystemInt3 = FALSE; return TRUE; } else { WriteProcessMemory(hDebuggeeProcess, pExceptionInfo->ExceptionRecord.ExceptionAddress, &OriginalCode, 1, NULL); } //2. 显示断点位置 printf("Int 3断点 : 0x%p rn", pExceptionInfo->ExceptionRecord.ExceptionAddress); //3. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //4. 修正EIP //printf("Eip : %xn",Context.Eip); Context.Eip--; SetThreadContext(hDebuggeeThread, &Context); //5. 显示反汇编代码、寄存器等 //6. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL AccessExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = TRUE; return bRet; } BOOL SingleStepExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = TRUE; return bRet; } BOOL ExceptionHandler(DEBUG_EVENT *pDebugEvent) { BOOL bRet = TRUE; EXCEPTION_DEBUG_INFO *pExceptionInfo = NULL; pExceptionInfo = &pDebugEvent->u.Exception; //得到线程句柄,后面要用 FnOpenThread MyOpenThread = (FnOpenThread)GetProcAddress(LoadLibrary("kernel32.dll"), "OpenThread"); hDebuggeeThread = MyOpenThread(THREAD_ALL_ACCESS, FALSE, pDebugEvent->dwThreadId); switch(pExceptionInfo->ExceptionRecord.ExceptionCode) { //INT 3异常 case EXCEPTION_BREAKPOINT: bRet = Int3ExceptionProc(pExceptionInfo); break; //访问异常 case EXCEPTION_ACCESS_VIOLATION: bRet = AccessExceptionProc(pExceptionInfo); break; //单步执行 case EXCEPTION_SINGLE_STEP: bRet = SingleStepExceptionProc(pExceptionInfo); break; } return bRet; } void SetInt3BreakPoint(LPVOID addr) { ReadProcessMemory(hDebuggeeProcess, addr, &OriginalCode, 1, NULL); BYTE int3[1] = { 0xcc }; WriteProcessMemory(hDebuggeeProcess, addr, int3, 1, NULL); } BOOL ExceptionTest() { BOOL nIsContinue = TRUE; DEBUG_EVENT debugEvent = {0}; BOOL bRet = TRUE; DWORD dwContinue = DBG_CONTINUE; //1.创建调试进程 STARTUPINFO startupInfo = {0}; PROCESS_INFORMATION pInfo = {0}; GetStartupInfo(&startupInfo); bRet = CreateProcess(DEBUGGEE, NULL, NULL, NULL, TRUE, DEBUG_PROCESS || DEBUG_ONLY_THIS_PROCESS, NULL, NULL, &startupInfo, &pInfo); if(!bRet) { printf("CreateProcess error: %d n", GetLastError()); return 0; } hDebuggeeProcess = pInfo.hProcess; //2.调试循环 while(nIsContinue) { bRet = WaitForDebugEvent(&debugEvent, INFINITE); if(!bRet) { printf("WaitForDebugEvent error: %d n", GetLastError()); return 0; } switch(debugEvent.dwDebugEventCode) { //1.异常 case EXCEPTION_DEBUG_EVENT: bRet = ExceptionHandler(&debugEvent); if(!bRet) dwContinue = DBG_EXCEPTION_NOT_HANDLED; break; //2. case CREATE_THREAD_DEBUG_EVENT: break; //3.创建进程 case CREATE_PROCESS_DEBUG_EVENT: SetInt3BreakPoint((PCHAR)debugEvent.u.CreateProcessInfo.lpStartAddress); break; //4. case EXIT_THREAD_DEBUG_EVENT: break; //5. case EXIT_PROCESS_DEBUG_EVENT: break; //6. case LOAD_DLL_DEBUG_EVENT: break; //7. case UNLOAD_DLL_DEBUG_EVENT: break; //8. case OUTPUT_DEBUG_STRING_EVENT: break; } bRet = ContinueDebugEvent(debugEvent.dwProcessId, debugEvent.dwThreadId, DBG_CONTINUE); } return 0; } int main(int argc, char* argv[]) { ExceptionTest(); return 0; }

实现效果

内存断点

描述:当需要在某块内存被访问时产生中断,可以使用内存断点。

内存断点能够分为两种类型:

内存访问:内存被读写时产生中断 内存写入:内存被写入时产生中断

原理:VirtualProtectEx

BOOL VirtualProtectEx( HANDLE hProcess, // handle to process LPVOID lpAddress, // region of committed pages SIZE_T dwSize, // size of region DWORD flNewProtect, // desired access protection PDWORD lpflOldProtect // old protection );

flNewProtect

内存访问:将指定内存的属性修改为PAGE_NOACCESS(修改后,PTE的P位等于0) 内存写入:将指定内存的属性修改为PAGE_EXECUTE_READ(修改后,PTE的P位等于1,R/W位等于0)

流程

被调试进程:

1)CPU访问错误的内存地址,触发页异常 2)查IDT表找到对应的中断处理函数(nt!_KiTrap0E) 3)CommonDispatchException 4)KiDispatchException 5)DbgkForwardException收集并发送调试事件

最终调用DbgkpSendApiMessage(x, x),第一个参数:消息类型,共有7种类型,第二个参数:是否挂起其它线程

调试器进程:

1)循环判断 2)取出调试事件 3)列出消息(寄存器/内存) 4)用户处理

在创建进程的地方使用内存断点

通过修改PTE的P=0来设置页不可访问

我们首先看一下EXCEPTION_DEBUG_INFO结构

然后再看ExceptionRecord

定位到_EXCEPTION_RECORD

到msdn里面看一下EXCEPTION_RECORD,这里主要关注ExceptionInformation

如果这个值为0有线程试图读这块内存,如果这个值为1则有线程试图写这块内存

这里显示出异常的信息,打印异常类型和异常地址

内存断点的EIP就是原EIP,不需要进行减的操作

实现代码如下

// Debug4.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <stdio.h> #include <windows.h> #include <tlhelp32.h> #define DEBUGGEE "C:\ipmsg.exe" //被调试进程ID,进程句柄,OEP DWORD dwDebuggeePID = 0; //被调试线程句柄 HANDLE hDebuggeeThread = NULL; HANDLE hDebuggeeProcess = NULL; //系统断点 BOOL bIsSystemInt3 = TRUE; //被INT 3覆盖的数据 CHAR OriginalCode = 0; //原始内存属性 DWORD dwOriginalProtect; //线程上下文 CONTEXT Context; typedef HANDLE (__stdcall *FnOpenThread) (DWORD, BOOL, DWORD); VOID InitDebuggeeInfo(DWORD dwPID, HANDLE hProcess) { dwDebuggeePID = dwPID; hDebuggeeProcess = hProcess; } DWORD GetProcessId(LPTSTR lpProcessName) { HANDLE hProcessSnap = NULL; PROCESSENTRY32 pe32 = {0}; hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); if(hProcessSnap == (HANDLE)-1) { return 0; } pe32.dwSize = sizeof(PROCESSENTRY32); if(Process32First(hProcessSnap, &pe32)) { do { if(!strcmp(lpProcessName, pe32.szExeFile)) return (int)pe32.th32ProcessID; } while (Process32Next(hProcessSnap, &pe32)); } else { CloseHandle(hProcessSnap); } return 0; } BOOL WaitForUserCommand() { BOOL bRet = FALSE; CHAR command; printf("COMMAND>"); command = getchar(); switch(command) { case 't': bRet = TRUE; break; case 'p': bRet = TRUE; break; case 'g': bRet = TRUE; break; } getchar(); return bRet; } BOOL Int3ExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; //1. 将INT 3修复为原来的数据(如果是系统断点,不用修复) if(bIsSystemInt3) { bIsSystemInt3 = FALSE; return TRUE; } else { WriteProcessMemory(hDebuggeeProcess, pExceptionInfo->ExceptionRecord.ExceptionAddress, &OriginalCode, 1, NULL); } //2. 显示断点位置 printf("Int 3断点 : 0x%p rn", pExceptionInfo->ExceptionRecord.ExceptionAddress); //3. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //4. 修正EIP Context.Eip--; SetThreadContext(hDebuggeeThread, &Context); //5. 显示反汇编代码、寄存器等 //6. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL AccessExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; DWORD dwAccessFlag; //访问类型 0为读 1为写 DWORD dwAccessAddr; //访问地址 DWORD dwProtect; //内存属性 //1. 获取异常信息,修改内存属性 dwAccessFlag = pExceptionInfo->ExceptionRecord.ExceptionInformation[0]; dwAccessAddr = pExceptionInfo->ExceptionRecord.ExceptionInformation[1]; printf("内存断点 : dwAccessFlag - %x dwAccessAddr - %x n", dwAccessFlag, dwAccessAddr); VirtualProtectEx(hDebuggeeProcess, (VOID*)dwAccessAddr, 1, dwOriginalProtect, &dwProtect); //2. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //3. 修正EIP(内存访问异常,不需要修正EIP) printf("Eip: 0x%p n", Context.Eip); //4. 显示汇编/寄存器等信息 //5. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL SingleStepExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = TRUE; return bRet; } BOOL ExceptionHandler(DEBUG_EVENT *pDebugEvent) { BOOL bRet = TRUE; EXCEPTION_DEBUG_INFO *pExceptionInfo = NULL; pExceptionInfo = &pDebugEvent->u.Exception; //得到线程句柄,后面要用 FnOpenThread MyOpenThread = (FnOpenThread)GetProcAddress(LoadLibrary("kernel32.dll"), "OpenThread"); hDebuggeeThread = MyOpenThread(THREAD_ALL_ACCESS, FALSE, pDebugEvent->dwThreadId); switch(pExceptionInfo->ExceptionRecord.ExceptionCode) { //INT 3异常 case EXCEPTION_BREAKPOINT: { bRet = Int3ExceptionProc(pExceptionInfo); break; } //访问异常 case EXCEPTION_ACCESS_VIOLATION: bRet = AccessExceptionProc(pExceptionInfo); break; //单步执行 case EXCEPTION_SINGLE_STEP: bRet = SingleStepExceptionProc(pExceptionInfo); break; } return bRet; } VOID SetInt3BreakPoint(LPVOID addr) { CHAR int3 = 0xCC; //1. 备份 ReadProcessMemory(hDebuggeeProcess, addr, &OriginalCode, 1, NULL); //2. 修改 WriteProcessMemory(hDebuggeeProcess, addr, &int3, 1, NULL); } VOID SetMemBreakPoint(PCHAR pAddress) { //1. 访问断点 VirtualProtectEx(hDebuggeeProcess, pAddress, 1, PAGE_NOACCESS, &dwOriginalProtect); //PTE P=0 //2. 写入断点 //VirtualProtectEx(hDebuggeeProcess, pAddress, 1, PAGE_EXECUTE_READ, &dwOriginalProtect); //PTE R/W=0 } int main(int argc, char* argv[]) { BOOL nIsContinue = TRUE; DEBUG_EVENT debugEvent = {0}; BOOL bRet = TRUE; DWORD dwContinue = DBG_CONTINUE; //1.创建调试进程 STARTUPINFO startupInfo = {0}; PROCESS_INFORMATION pInfo = {0}; GetStartupInfo(&startupInfo); bRet = CreateProcess(DEBUGGEE, NULL, NULL, NULL, TRUE, DEBUG_PROCESS || DEBUG_ONLY_THIS_PROCESS, NULL, NULL, &startupInfo, &pInfo); if(!bRet) { printf("CreateProcess error: %d n", GetLastError()); return 0; } hDebuggeeProcess = pInfo.hProcess; //2.调试循环 while(nIsContinue) { bRet = WaitForDebugEvent(&debugEvent, INFINITE); if(!bRet) { printf("WaitForDebugEvent error: %d n", GetLastError()); return 0; } switch(debugEvent.dwDebugEventCode) { //1.异常 case EXCEPTION_DEBUG_EVENT: bRet = ExceptionHandler(&debugEvent); if(!bRet) dwContinue = DBG_EXCEPTION_NOT_HANDLED; break; //2. case CREATE_THREAD_DEBUG_EVENT: break; //3.创建进程 case CREATE_PROCESS_DEBUG_EVENT: //int3 断点 //SetInt3BreakPoint((PCHAR)debugEvent.u.CreateProcessInfo.lpStartAddress); //内存断点 SetMemBreakPoint((PCHAR)debugEvent.u.CreateProcessInfo.lpStartAddress); break; //4. case EXIT_THREAD_DEBUG_EVENT: break; //5. case EXIT_PROCESS_DEBUG_EVENT: break; //6. case LOAD_DLL_DEBUG_EVENT: break; //7. case UNLOAD_DLL_DEBUG_EVENT: break; //8. case OUTPUT_DEBUG_STRING_EVENT: break; } bRet = ContinueDebugEvent(debugEvent.dwProcessId, debugEvent.dwThreadId, DBG_CONTINUE); } return 0; }

实现效果如下

硬件断点

1.与软件断点与内存断点不同,硬件断点不依赖被调试程序,而是依赖于CPU中的调试寄存器

2.调试寄存器有7个,分别为Dr0~Dr7

3.用户最多能够设置4个硬件断点,这是由于只有Dr0~Dr3用于存储线性地址。

4.其中,Dr4和Dr5是保留的。

假如在Dr0寄存器中写入线性地址,是否所有线程都会受影响?其实不会,每个线程都拥有一份独立的寄存器,切换线程时,寄存器的值也会被切换。

设置硬件断点

Dr0~Dr3用于设置硬件断点,由于只有4个断点寄存器,所以最多只能设置4个硬件调试断点。在7个寄存器里面,Dr7是最重要的寄存器

L0/G0 ~ L3/G3:控制Dr0~Dr3是否有效,局部还是全局;每次异常后,Lx都被清零,Gx不清零。

若Dr0有效,L0=1则为局部,G0=1则为全局,以此类推

断点长度(LENx):00(1字节)、01(2字节)、11(4字节)

通过DR7的LEN控制

断点类型(R/Wx):00(执行断点)、01(写入断点)、11(访问断点)

流程

被调试进程:

1)CPU执行时检测当前线性地址与调试寄存器(Dr0~Dr3)中的线性地址相等。 2)查IDT表找到对应的中断处理函数(nt!_KiTrap01) 3)CommonDispatchException 4)KiDispatchException 5)DbgkForwardException收集并发送调试事件

最终调用DbgkpSendApiMessage(x, x),第一个参数:消息类型,第二个参数:是否挂起其它线程

调试器进程:

1)循环判断 2)取出调试事件 3)列出信息:寄存器、内存 4)用户处理

处理硬件断点

1)硬件调试断点产生的异常是 STATUS_SINGLE_STEP(单步异常) 2)检测Dr6寄存器的B0~B3:哪个寄存器触发的异常

这里硬件断点有两种情况,一种情况是dr0-dr3寄存器引发的异常,另外一种情况就是TF=1引发的异常

这里如果是DR0寄存器引发的异常,那么B0=1,以此类推,如果是TF=1引发的异常,那么DR6的低4位为全0

首先看一下异常处理函数

BOOL SingleStepExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; //1. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //2. 判断是否是硬件断点导致的异常 if(Context.Dr6 & 0xF) //B0~B3不为空 硬件断点 { //2.1 显示断点信息 printf("硬件断点:%x 0x%p n", Context.Dr7&0x00030000, Context.Dr0); //2.2 将断点去除 Context.Dr0 = 0; Context.Dr7 &= 0xfffffffe; } else //单步异常 { //2.1 显示断点信息 printf("单步:0x%p n", Context.Eip); //2.2 将断点去除 Context.Dr7 &= 0xfffffeff; } SetThreadContext(hDebuggeeThread, &Context); // 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; }

之前我们是在创建进程的时候进行断点,但是因为硬件断点需要在线程创建完成之后,设置在被调试程序的上下文中

因此当被调试程序触发调试器设置的INT 3断点时,此时设置硬件断点较为合理

再就是硬件断点的代码,这里把Dr0寄存器置1,然后把16、17为置0为执行断点,异常长度为1字节(18、19位置0),地址的话就是int3断点的地址 1

VOID SetHardBreakPoint(PVOID pAddress) { //1. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //2. 设置断点位置 Context.Dr0 = (DWORD)pAddress; Context.Dr7 |= 1; //3. 设置断点长度和类型 Context.Dr7 &= 0xfff0ffff; //执行断点(16、17位 置0) 1字节(18、19位 置0) //5. 设置线程上下文 SetThreadContext(hDebuggeeThread, &Context); }

完整代码如下

// Debug4.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <stdio.h> #include <windows.h> #include <tlhelp32.h> #define DEBUGGEE "C:\ipmsg.exe" //被调试进程ID,进程句柄,OEP DWORD dwDebuggeePID = 0; //被调试线程句柄 HANDLE hDebuggeeThread = NULL; HANDLE hDebuggeeProcess = NULL; //系统断点 BOOL bIsSystemInt3 = TRUE; //被INT 3覆盖的数据 CHAR OriginalCode = 0; //原始内存属性 DWORD dwOriginalProtect; //线程上下文 CONTEXT Context; typedef HANDLE (__stdcall *FnOpenThread) (DWORD, BOOL, DWORD); VOID InitDebuggeeInfo(DWORD dwPID, HANDLE hProcess) { dwDebuggeePID = dwPID; hDebuggeeProcess = hProcess; } DWORD GetProcessId(LPTSTR lpProcessName) { HANDLE hProcessSnap = NULL; PROCESSENTRY32 pe32 = {0}; hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); if(hProcessSnap == (HANDLE)-1) { return 0; } pe32.dwSize = sizeof(PROCESSENTRY32); if(Process32First(hProcessSnap, &pe32)) { do { if(!strcmp(lpProcessName, pe32.szExeFile)) return (int)pe32.th32ProcessID; } while (Process32Next(hProcessSnap, &pe32)); } else { CloseHandle(hProcessSnap); } return 0; } BOOL WaitForUserCommand() { BOOL bRet = FALSE; CHAR command; printf("COMMAND>"); command = getchar(); switch(command) { case 't': bRet = TRUE; break; case 'p': bRet = TRUE; break; case 'g': bRet = TRUE; break; } getchar(); return bRet; } VOID SetHardBreakPoint(PVOID pAddress) { //1. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //2. 设置断点位置 Context.Dr0 = (DWORD)pAddress; Context.Dr7 |= 1; //3. 设置断点长度和类型 Context.Dr7 &= 0xfff0ffff; //执行断点(16、17位 置0) 1字节(18、19位 置0) //5. 设置线程上下文 SetThreadContext(hDebuggeeThread, &Context); } BOOL Int3ExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; //1. 将INT 3修复为原来的数据(如果是系统断点,不用修复) if(bIsSystemInt3) { bIsSystemInt3 = FALSE; return TRUE; } else { WriteProcessMemory(hDebuggeeProcess, pExceptionInfo->ExceptionRecord.ExceptionAddress, &OriginalCode, 1, NULL); } //2. 显示断点位置 printf("Int 3断点:0x%p rn", pExceptionInfo->ExceptionRecord.ExceptionAddress); //3. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //4. 修正EIP Context.Eip--; SetThreadContext(hDebuggeeThread, &Context); //5. 显示反汇编代码、寄存器等 /* 硬件断点需要设置在被调试进程的的线程上下文中。 因此当被调试程序触发调试器设置的INT 3断点时,此时设置硬件断点较为合理。 */ SetHardBreakPoint((PVOID)((DWORD)pExceptionInfo->ExceptionRecord.ExceptionAddress 1)); //6. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL AccessExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; DWORD dwAccessFlag; //访问类型 0为读 1为写 DWORD dwAccessAddr; //访问地址 DWORD dwProtect; //内存属性 //1. 获取异常信息,修改内存属性 dwAccessFlag = pExceptionInfo->ExceptionRecord.ExceptionInformation[0]; dwAccessAddr = pExceptionInfo->ExceptionRecord.ExceptionInformation[1]; printf("内存断点 : dwAccessFlag - %x dwAccessAddr - %x n", dwAccessFlag, dwAccessAddr); VirtualProtectEx(hDebuggeeProcess, (VOID*)dwAccessAddr, 1, dwOriginalProtect, &dwProtect); //2. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //3. 修正EIP(内存访问异常,不需要修正EIP) printf("Eip: 0x%p n", Context.Eip); //4. 显示汇编/寄存器等信息 //5. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL SingleStepExceptionProc(EXCEPTION_DEBUG_INFO *pExceptionInfo) { BOOL bRet = FALSE; //1. 获取线程上下文 Context.ContextFlags = CONTEXT_FULL | CONTEXT_DEBUG_REGISTERS; GetThreadContext(hDebuggeeThread, &Context); //2. 判断是否是硬件断点导致的异常 if(Context.Dr6 & 0xF) //B0~B3不为空 硬件断点 { //2.1 显示断点信息 printf("硬件断点:%x 0x%p n", Context.Dr7&0x00030000, Context.Dr0); //2.2 将断点去除 Context.Dr0 = 0; Context.Dr7 &= 0xfffffffe; } else //单步异常 { //2.1 显示断点信息 printf("单步:0x%p n", Context.Eip); //2.2 将断点去除 Context.Dr7 &= 0xfffffeff; } SetThreadContext(hDebuggeeThread, &Context); //6. 等待用户命令 while(bRet == FALSE) { bRet = WaitForUserCommand(); } return bRet; } BOOL ExceptionHandler(DEBUG_EVENT *pDebugEvent) { BOOL bRet = TRUE; EXCEPTION_DEBUG_INFO *pExceptionInfo = NULL; pExceptionInfo = &pDebugEvent->u.Exception; //得到线程句柄,后面要用 FnOpenThread MyOpenThread = (FnOpenThread)GetProcAddress(LoadLibrary("kernel32.dll"), "OpenThread"); hDebuggeeThread = MyOpenThread(THREAD_ALL_ACCESS, FALSE, pDebugEvent->dwThreadId); switch(pExceptionInfo->ExceptionRecord.ExceptionCode) { //INT 3异常 case EXCEPTION_BREAKPOINT: bRet = Int3ExceptionProc(pExceptionInfo); break; //访问异常 case EXCEPTION_ACCESS_VIOLATION: bRet = AccessExceptionProc(pExceptionInfo); break; //单步执行 case EXCEPTION_SINGLE_STEP: bRet = SingleStepExceptionProc(pExceptionInfo); break; } return bRet; } VOID SetInt3BreakPoint(LPVOID addr) { CHAR int3 = 0xCC; //1. 备份 ReadProcessMemory(hDebuggeeProcess, addr, &OriginalCode, 1, NULL); //2. 修改 WriteProcessMemory(hDebuggeeProcess, addr, &int3, 1, NULL); } VOID SetMemBreakPoint(PCHAR pAddress) { //1. 访问断点 VirtualProtectEx(hDebuggeeProcess, pAddress, 1, PAGE_NOACCESS, &dwOriginalProtect); //PTE P=0 //2. 写入断点 //VirtualProtectEx(hDebuggeeProcess, pAddress, 1, PAGE_EXECUTE_READ, &dwOriginalProtect); //PTE R/W=0 } int main(int argc, char* argv[]) { BOOL nIsContinue = TRUE; DEBUG_EVENT debugEvent = {0}; BOOL bRet = TRUE; DWORD dwContinue = DBG_CONTINUE; //1.创建调试进程 STARTUPINFO startupInfo = {0}; PROCESS_INFORMATION pInfo = {0}; GetStartupInfo(&startupInfo); bRet = CreateProcess(DEBUGGEE, NULL, NULL, NULL, TRUE, DEBUG_PROCESS || DEBUG_ONLY_THIS_PROCESS, NULL, NULL, &startupInfo, &pInfo); if(!bRet) { printf("CreateProcess error: %d n", GetLastError()); return 0; } hDebuggeeProcess = pInfo.hProcess; //2.调试循环 while(nIsContinue) { bRet = WaitForDebugEvent(&debugEvent, INFINITE); if(!bRet) { printf("WaitForDebugEvent error: %d n", GetLastError()); return 0; } switch(debugEvent.dwDebugEventCode) { //1.异常 case EXCEPTION_DEBUG_EVENT: bRet = ExceptionHandler(&debugEvent); if(!bRet) dwContinue = DBG_EXCEPTION_NOT_HANDLED; break; //2. case CREATE_THREAD_DEBUG_EVENT: break; //3.创建进程 case CREATE_PROCESS_DEBUG_EVENT: //int3 断点 SetInt3BreakPoint((PCHAR)debugEvent.u.CreateProcessInfo.lpStartAddress); //内存断点 //SetMemBreakPoint((PCHAR)debugEvent.u.CreateProcessInfo.lpStartAddress); break; //4. case EXIT_THREAD_DEBUG_EVENT: break; //5. case EXIT_PROCESS_DEBUG_EVENT: break; //6. case LOAD_DLL_DEBUG_EVENT: break; //7. case UNLOAD_DLL_DEBUG_EVENT: break; //8. case OUTPUT_DEBUG_STRING_EVENT: break; } bRet = ContinueDebugEvent(debugEvent.dwProcessId, debugEvent.dwThreadId, DBG_CONTINUE); } return 0; }

实现效果如下

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