Hello list!

I want to warn you about Cross-Site Scripting vulnerability in plugin
MT-Cumulus for Movable Type.

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Affected products:
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At first the developer made widget Flash Tag Cloud For MT 4, and later made 
full-fledged plugin MT-Cumulus for Movable Type. And in both applications 
there is this XSS vulnerability.

Vulnerable are widget Flash Tag Cloud For MT 4 and plugin MT-Cumulus v1.02 
and previous versions.

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Details:
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This XSS is similar to XSS vulnerability in WP-Cumulus, because it's using
tagcloud.swf made by author of WP-Cumulus. About such vulnerabilities I
wrote in 2009-2011, particularly about millions of flash files tagcloud.swf
which are vulnerable to XSS attacks I mentioned in my article XSS
vulnerabilities in 34 millions flash files
(http://lists.webappsec.org/pipermail/websecurity_lists.webappsec.org/2010-January/006033.html).

XSS (WASC-08):

For Flash Tag Cloud For MT 4:

http://site/scripts/tagcloud.swf?mode=tags&tagcloud=%3Ctags%3E%3Ca+href='javascript:alert(document.cookie)'+style='font-size:+40pt'%3EClick%20me%3C/a%3E%3C/tags%3E

For MT-Cumulus:

http://site/mt/mt-static/plugins/Cumulus/tagcloud.swf?mode=tags&tagcloud=%3Ctags%3E%3Ca+href='javascript:alert(document.cookie)'+style='font-size:+40pt'%3EClick%20me%3C/a%3E%3C/tags%3E

Code will execute after click. It's strictly social XSS. Also it's possible
to conduct (like in WP-Cumulus) HTML Injection attack.

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Timeline:
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2011.05.11 - disclosed at my site.
2011.05.12 - informed developer of these widget and plugin.

I mentioned about this vulnerability at my site
(http://websecurity.com.ua/5139/).

Best wishes & regards,
MustLive
Administrator of Websecurity web site
http://websecurity.com.ua