Full Disclosure: Skype videomood XSS

[Miroslav Lučinskij <miroslav.lucinskij () critical lt>]

I want to share some of our thoughts on Skype security. I will try to be short: Skype has a feature, which allows user 
to insert a video into his mood - video selection is done through skype partners and is based on regular WEB 
functionality. So this feature practically inherits WEB's problems - in this particular case it's XSS attacks.

In fact, Skype security is now dependant on their partners website security as no additional measures are taken to 
filter possible malicious content, that may come from the partners - dailymotion and metacafe are treated like trusted 
resources. This is wrong and may cause trouble.

We were able to find some permanent XSS vectors in dailymotion.com: videos have a 'Title' field, which is not properly 
filtered and returned to user in certain conditions. So it becomes possible to execute malicious script content when 
user is searching for a video to add to his mood. You may also test it by entering word 'saugumas' in dailymotion.com 
video search field.

Screenshots are available here: http://www.critical.lt/?opinions/show/1470 

Best regards,

Miroslav Lučinskij,
Critical Security
Lithuania, Vilnius

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