程序的自我修改

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本文目的在于向读者说明程序进行自我修改的基本方法，并希望可以起到抛砖引玉的作用。 如果读者有更好的方法或见解，欢迎来信交流E-mail: default_and_default@yahoo.cn /*////////////////////////////////////////////////////////////////////////////// This program will modify itself at the running time, These  methods will be very useful in some situations, Gook Luck! //////////////////////////////////////////////////////////////////////////////*/ #include<stdio.h> #include<windows.h> void main() {   TCHAR Info001[MAX_PATH]="Welcome to Big Apple!";   TCHAR Info002[MAX_PATH]="Welcome to Washington!";   char temp=(char)0x90;   WORD temp001=0x9090;   DWORD temp002=0x90909090;   PVOID BaseAddressOne=NULL;   PVOID BaseAddressTwo=NULL;   _asm   {     mov BaseAddressOne,offset LabelOne     mov BaseAddressTwo,offset LabelTwo   }   MessageBox(NULL,Info001,"Information",MB_OK|MB_ICONINFORMATION); //a kind of method to modify itself   WriteProcessMemory(GetCurrentProcess(),BaseAddressTwo,&temp001,2,NULL);   WriteProcessMemory(GetCurrentProcess(),BaseAddressOne,&temp001,2,NULL); /* //Another method to modify itself,this method needs to modify the code section's //characteristics in PE file.   _asm   {     mov ebx,BaseAddressOne     mov ecx,BaseAddressTwo     mov dx,temp001     mov [ebx],dx     mov [ecx],dx   } */ LabelTwo:   _asm   {     jmp LabelOne   }   _asm   {     nop     nop     nop   }   MessageBox(NULL,Info002,"Information",MB_OK|MB_ICONINFORMATION); LabelOne:   _asm   {     jmp Over   }   MessageBox(NULL,Info002,"Information",MB_OK|MB_ICONINFORMATION); Over:   return; } 编译这个程序，我们发现WriteProcessMemory() 成功修改了程序自身代码，程序运行正常。 然后我们屏蔽程序中的WriteProcessMemory()调用，用/*  */之中的代码完成自我修改， 运行后会发现系统抛出异常 Access Violation.这是因为PE 中 代码节的属性默认为 0x60000020， 20 表示代码 20000000表示可执行，40000000表示可读，如果我们在此基础上加上 0x80000000(可写） 操作系统的loader在装载可执行文件时，便会将存放代码节数据的内存标记为可读，可写，可执行。 这样就不会有异常了。 读者可使用下面的程序来修改节属性： /**************************************************************************************/ //The following code is used to modify characteristics of sections #include<windows.h> #include<stdio.h> BOOL ModifyCharacteristicsOfSections (LPCTSTR FileName) {   DWORD i=0;   HANDLE hDestinationFile=NULL;   TCHAR  DestinationPEFile[MAX_PATH];   DWORD NumberOfBytesRead=0;   //Number of bytes read   DWORD NumberOfBytesWritten=0; //Number of bytes written   DWORD ImageNtSignature=0;  //PE signature   DWORD OffsetOfNewHeader=0;   DWORD NumberOfSections=0;   DWORD SizeOfSectionTable=0;           //size of section table      HANDLE hGlobalAllocatedMemory=NULL;  //use GlobalAlloc();      PIMAGE_SECTION_HEADER pImageSectionHeader=NULL; //a pointer to IMAGE_SECTION_TABLE   IMAGE_DOS_HEADER ImageDosHeader;   IMAGE_NT_HEADERS ImageNTHeaders;   IMAGE_FILE_HEADER ImageFileHeader;      IMAGE_OPTIONAL_HEADER ImageOptionalHeader;   IMAGE_SECTION_HEADER ImageSectionHeader;   DWORD dwFileSize=0;   RtlZeroMemory(&ImageDosHeader,sizeof(IMAGE_DOS_HEADER));   RtlZeroMemory(&ImageNTHeaders,sizeof(IMAGE_NT_HEADERS));   RtlZeroMemory(&ImageFileHeader,sizeof(IMAGE_FILE_HEADER));      RtlZeroMemory(&ImageOptionalHeader,sizeof(IMAGE_OPTIONAL_HEADER));   RtlZeroMemory(&ImageSectionHeader,sizeof(IMAGE_SECTION_HEADER));      strcpy(DestinationPEFile,FileName);   hDestinationFile=CreateFile(DestinationPEFile,     FILE_WRITE_DATA|FILE_READ_DATA,     FILE_SHARE_WRITE,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_ARCHIVE,NULL);      if(hDestinationFile==INVALID_HANDLE_VALUE)   { //    printf("/nCreateFile() fails!Can't open file. Please try again!/n"); //    CloseHandle(hDestinationFile);     return TRUE;   }   else   {     dwFileSize=GetFileSize(hDestinationFile,NULL);   }   SetFilePointer(hDestinationFile,0,NULL,FILE_BEGIN); //Revert the file pointer,this is very important.      ReadFile(hDestinationFile,&ImageDosHeader,     sizeof(IMAGE_DOS_HEADER),&NumberOfBytesRead,NULL);   if(NumberOfBytesRead!=sizeof(IMAGE_DOS_HEADER))   { //    printf("/nReadFile() fails! Can't get IMAGE_DOS_HEADER./n");     CloseHandle(hDestinationFile);     return FALSE;   }      OffsetOfNewHeader=ImageDosHeader.e_lfanew; //File address of new exe header      SetFilePointer(hDestinationFile,(LONG)OffsetOfNewHeader,NULL,FILE_BEGIN);      ReadFile(hDestinationFile,&ImageNTHeaders,     sizeof(IMAGE_NT_HEADERS),&NumberOfBytesRead,NULL); //Retrieve IMAGE_NT_HEADERS   if(NumberOfBytesRead!=sizeof(IMAGE_NT_HEADERS))   {     CloseHandle(hDestinationFile);     return FALSE;   }   if(ImageNTHeaders.Signature!=0x00004550)   { //    printf("Error./nPE signature is invalid!/n");     CloseHandle(hDestinationFile);     return FALSE;   }         SetFilePointer(hDestinationFile,OffsetOfNewHeader+4,NULL,FILE_BEGIN);  //Set the file pointer to point to IMAGE_FILE_HEADER   ReadFile(hDestinationFile,&ImageFileHeader,     sizeof(IMAGE_FILE_HEADER),&NumberOfBytesRead,NULL); //Retrieve IMAGE_FILE_HEADER   if(NumberOfBytesRead!=sizeof(IMAGE_FILE_HEADER))   { //    printf("/nReadFile() fails! Can't get IMAGE_FILE_HEADER./n");     CloseHandle(hDestinationFile);     return FALSE;   }   if(ImageFileHeader.NumberOfSections<1)   {     CloseHandle(hDestinationFile);     return FALSE;   }      if(dwFileSize<(sizeof(IMAGE_DOS_HEADER)+sizeof(IMAGE_NT_HEADERS)+sizeof(IMAGE_SECTION_HEADER)*ImageFileHeader.NumberOfSections))   {     CloseHandle(hDestinationFile);     return FALSE;   }   ReadFile(hDestinationFile,&ImageOptionalHeader,     sizeof(IMAGE_OPTIONAL_HEADER),&NumberOfBytesRead,NULL); //Retrieve IMAGE_OPTIONAL_HEADER   if(NumberOfBytesRead!=sizeof(IMAGE_OPTIONAL_HEADER))   { //    printf("/nReadFile() fails! Can't get IMAGE_OPTIONAL_HEADER./n");     CloseHandle(hDestinationFile);     return FALSE;   }   if(ImageOptionalHeader.SectionAlignment<ImageOptionalHeader.FileAlignment)   {     CloseHandle(hDestinationFile);     return FALSE;   }   NumberOfSections=ImageFileHeader.NumberOfSections; //Number of sections   SizeOfSectionTable=sizeof(IMAGE_SECTION_HEADER)*NumberOfSections; //Get the size of Section Table      hGlobalAllocatedMemory=GlobalAlloc(GPTR,SizeOfSectionTable);      //Allocate memory and initialize with zero   if(hGlobalAllocatedMemory==NULL)   { //    printf("/nGlobalAlloc() failed! Please try again./n"); //if failed,return     CloseHandle(hDestinationFile);     return FALSE;   }           pImageSectionHeader=(PIMAGE_SECTION_HEADER)hGlobalAllocatedMemory; //Convert a handle to a pointer to IMAGE_SECTION_HEADER      for(i=0;i<NumberOfSections;i++)  //Retrieve the Section Table   {     ReadFile(hDestinationFile,pImageSectionHeader+i,       sizeof(IMAGE_SECTION_HEADER),&NumberOfBytesRead,NULL);     if(NumberOfBytesRead!=sizeof(IMAGE_SECTION_HEADER))     { //      printf("Error.Can't get IMAGE_SECTION_HEADER./n");       CloseHandle(hDestinationFile);       return FALSE;     }   }   for(i=0;i<NumberOfSections;i++)   {     DWORD dwTempCharacteristics=0;     if((*(pImageSectionHeader+i)).PointerToRawData+(*(pImageSectionHeader+i)).SizeOfRawData>dwFileSize)     {       CloseHandle(hDestinationFile);       return FALSE;     }     if((*(pImageSectionHeader+i)).PointerToRawData % ImageOptionalHeader.FileAlignment!=0)     {       CloseHandle(hDestinationFile);       return FALSE;     }     printf("/nThe name of the section%d: ",i);     printf("%s/n",(*(pImageSectionHeader+i)).Name);          printf("Characteristics: %#x/n",(*(pImageSectionHeader+i)).Characteristics);     printf("/nPlease input the new characteristics of the section./n");     printf("If you enter 0,the characteristics of the section will not be modified./n");     scanf("%x",&dwTempCharacteristics);     if(dwTempCharacteristics!=0)       (*(pImageSectionHeader+i)).Characteristics=dwTempCharacteristics;       printf("------------------------------------------------------");   }   SetFilePointer(hDestinationFile,-((long)SizeOfSectionTable),NULL,FILE_CURRENT); //Set the file poiner   WriteFile(hDestinationFile,pImageSectionHeader,SizeOfSectionTable,&NumberOfBytesWritten,NULL);   if(NumberOfBytesWritten==SizeOfSectionTable)   {     printf("/nComplete successfully!/n");   }   else   {        printf("/nWriteFile() failed!/n");   }   GlobalFree(hGlobalAllocatedMemory); //Free memory   CloseHandle(hDestinationFile);   return TRUE;     } void main(int argc,char *argv[]) {   if(argc!=2)   {     printf("Error/nUsage:ModifyCharacteristicsOfSections CompleteDestinationFileName/n");     return;   }   if(!ModifyCharacteristicsOfSections(argv[1]))   {     printf("/nError.This usually means that this file is not a valid PE file or/n");     printf("that this PE file has been modified by another program,for example,shell programm./n");   } } /**********************************************************************************************/ 以下是上面程序的输出信息： The name of the section0: .text Characteristics: 0x60000020 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. e0000020 ------------------------------------------------------ The name of the section1: .rdata Characteristics: 0x40000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section2: .data Characteristics: 0xc0000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section3: .idata Characteristics: 0xc0000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section4: .reloc Characteristics: 0x42000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ Complete successfully! //////////////////////////////////////////////////////////////////////////// The name of the section0: .text Characteristics: 0xe0000020 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section1: .rdata Characteristics: 0x40000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section2: .data Characteristics: 0xc0000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section3: .idata Characteristics: 0xc0000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ The name of the section4: .reloc Characteristics: 0x42000040 Please input the new characteristics of the section. If you enter 0,the characteristics of the section will not be modified. 0 ------------------------------------------------------ Complete successfully!