21 Feb 03:31
another homograph attach: BIDI char
Soobok Lee <lsb <at> lsb.org>
2005-02-21 02:31:24 GMT
2005-02-21 02:31:24 GMT
javascript:void(window.open(unescape("http://www.microsoft.com%u202e.uni.cc/%u1160%u1160%u1160"),"_self"))
If some IDNA implementation does not handle BIDI filtering/verifying
well, you can see similar results as "slash-space combination".
%u202e is a bidi directional formatter (RLO, right-to-left) and should
not be filtered char-by-char basis, because the char
plays a crucual role in arabic/hebrew writings. You can refer to
stringprep/nameprep document for details of BIDI checking part.
Good implementations of IDNA would not suffer from the above attack.
But, current MSIE does not support IDNA, while it
still allow arbitrary utf-8 chars. So, current MSIE is exploitable for
malicious phinshing attempts. I don't know whether this works
for filefox/mozilla.
The previous example,
javascript:void(window.open(unescape("http://www.microsoft.com%u2044%u1160%u1160%u1160.uni.cc/"),"_self"))
You can replace %u2044 with %u2205,%u3033 etc. I am now searching more
slash/space like chars. I will post them here.
Soobok
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