Bart De Smet's on-line blog (0x2B | ~0x2B, that's the question)
Read more on http://support.microsoft.com/kb/886903 and http://www.microsoft.com/technet/security/Bulletin/ms05-004.mspx. It's currently under review at http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0847.
The Microsoft .NET forms authentication capability allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash).
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