Mambo SiteServer exploit gains administrative privileges

From: Simen Bergo (sbergo@thesource.no)
Date: 02/24/03

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    Date: 24 Feb 2003 17:08:16 -0000
    From: Simen Bergo <sbergo@thesource.no>
    To: bugtraq@securityfocus.com
    
    
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    MAMBO SITESERVER EXPLOIT GAINS ADMINISTRATIVE PRIVILEGES
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
    Ż
    PROGRAM: Mambo SiteServer
    HOMEPAGE: http://www.mamboserver.com/
    TESTED: Mambo 4.0.12 RC2
    LOGIN REQUIRED: No

    PROOF OF CONCEPT
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
    Ż
    I have created an exploit that will gain access to the host you specify.
    It can be found at the URL below, but must only be used on your own website
    for testing purposes.

    http://www.voidnull.com/exploit/mamboexp.phps

    DESCRIPTION
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
    Ż
    "Mambo SiteServer is the finest open source Web Content Management System
    available today." (direct quote from the Mambo SiteServer website)

    A vulnerability in /administrator/index2.php allows any user to gain
    administrator access as long as they know any sessionid in the session
    table the script uses. (The code that is vulnerable is too big to include
    here)

    Actually, you would think just logging in as a normal user would create
    this sessionid, however a bug in the PHP sourcecode of the project make
    sure this does not happen.

    Anyone with a slight knowledge of PHP knows that when you set a cookie,
    it is not updated until you refresh the webpage. Anyone but the coders
    of Mambo SiteServer, that is:

    setcookie("sessioncookie", "$sessionID");
    if ($HTTP_COOKIE_VARS["sessioncookie"]!="") {
      $query="INSERT into ".$dbprefix."session set
    session_id='$cryptSessionID', guest='', userid='$uid',
    usertype='$usertype', gid='$gid', username='$username'";
      $database->openConnectionNoReturn($query);
    }

    As we can see, Mambo SiteServer checks if the cookie has been set before
    it inserts the sessionid into the table. As it has not yet been set, no
    sessionid is inserted and therefore we cannot "login" to the
    administrator directory either.

    Moving on in the sourcecode, to SessionCookie.php (which is called when
    you logout), we can see that a sessionid is inserted whenever you logout.
    Why? I have no idea.

    $current_time = time();
    if ($HTTP_COOKIE_VARS["sessioncookie"]==""){
      $randnum=getSessionID1();
      ...
      $cryptrandnum=md5($randnum);
      ...
      setcookie("sessioncookie", "$randnum");
      $guest=1;
      $query="INSERT into ".$dbprefix."session SET username='',
    time=$current_time, session_id='$cryptrandnum', guest=$guest";
      $database->openConnectionNoReturn($query);
    }

    A cookie, looking something like the following will now be sent to the
    browser:

    sessioncookie=nh54OQIZb8ybaA2CNNdU1046102063

    All we have to do is MD5-encrypt it, since that is what was done to the
    session that was inserted to the MySQL-table. In this example the encrypted
    version is:

    0ebda5bbba49dc226b4ed8fc801f1d98

    By accessing /administrator/index2.php with this session, Mambo SiteServer
    will think that we are the administrator logged in:

    /administrator/index2.php?session_id=0ebda5bbba49dc226b4ed8fc801f1d98

    SUMMARY
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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    Gaining administrative privileges gives you access to all MySQL-databases,
    user passwords, news, polls and everything else the server has. Many
    websites run Mambo SiteServer in addition to other scripts that requires
    MySQL, and this is therefore a huge threat to many webmasters.

    SOLUTIONS
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
    Ż
    Until Mambo release a patch for this vulnerability I suggest password-
    protecting your /administrator directory with .htaccess.

    VENDOR STATUS
    ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
    Ż
    The vendor has reportedly been notified. They are currently developing
    a patch for this vulnerability.