FINAL 2번

#include "../common/common.c"
#include "../common/malloc.c"

#define NAME "final2"
#define UID 0
#define GID 0
#define PORT 2993

#define REQSZ 128

void check_path(char *buf)
{
  char *start;
  char *p;
  int l;

  /*
  * Work out old software bug
  */

  p = rindex(buf, '/');
  l = strlen(p);
  if(p) {
      start = strstr(buf, "ROOT");
      if(start) {
          while(*start != '/') start--;
          memmove(start, p, l);
          printf("moving from %p to %p (exploit: %s / %d)\n", p, start, start < buf ?
          "yes" : "no", start - buf);
      }
  }
}

int get_requests(int fd)
{
  char *buf;
  char *destroylist[256];
  int dll;
  int i;

  dll = 0;
  while(1) {
      if(dll >= 255) break;

      buf = calloc(REQSZ, 1);
      if(read(fd, buf, REQSZ) != REQSZ) break;

      if(strncmp(buf, "FSRD", 4) != 0) break;

      check_path(buf + 4);     

      dll++;
  }

  for(i = 0; i < dll; i++) {
                write(fd, "Process OK\n", strlen("Process OK\n"));
      free(destroylist[i]);
  }
}

int main(int argc, char **argv, char **envp)
{
  int fd;
  char *username;

  /* Run the process as a daemon */
  background_process(NAME, UID, GID); 
  
  /* Wait for socket activity and return */
  fd = serve_forever(PORT);

  /* Set the client socket to STDIN, STDOUT, and STDERR */
  set_io(fd);

  get_requests(fd);
}

DFB를 이용하여 공격을 할 것이다.

저번에 했던 방법으로 pre_size와 chunk_size

0xfffffffc를 넣는다 그 후fd값에 got주소를 넣고 bk에 shell코드를 삽입 하기로 했다.