[WEB SECURITY] Re: [Full-disclosure] noise about full-width encoding bypass?

Chris Weber chris at mail.casabasec.com
Mon May 21 15:24:51 EDT 2007


Hold up a second folks, you're telling this list now that ASP.NET will
decompose various character sets like those containing your full-width single
quote, into it's ASCII equivalent.  Brian I think you should've stuck to your
original story because I'm almost certain this is completely untrue.  

If it were true then we'd have some dire state of emergency on our hands no? 
Compatibility decomposition and canonical composition are a function of the
Unicode normalization forms in use (http://unicode.org/reports/tr15/).  

*In particular, forms KD and KC would do what you're saying, but those aren't
commonly in use afaik.  Developers should be very cautious when normalizing to
these forms.

If you've managed to find some specific ASP.NET classes which normalize to
problematic forms KD/KC then you should let us know, but just saying all of
ASP.NET does this would be a huge stretch.  The framework supports all four
normalization methods
(http://msdn2.microsoft.com/en-us/winfx/system.string.aspx) and it's up to
developers to implement the ones they need.






---------- Original Message -----------
From: ascii <ascii at katamail.com>
To: Brian Eaton <eaton.lists at gmail.com>
Cc: Web Security <websecurity at webappsec.org>, Full-Disclosure
<full-disclosure at lists.grok.org.uk>
Sent: Mon, 21 May 2007 23:01:26 +0200
Subject: [WEB SECURITY] Re: [Full-disclosure] noise about full-width encoding
bypass?

> Brian Eaton wrote:
> > To summarize what I've heard from various sources: I am missing
> > something important. =)  Both PHP and ASP.NET will decode these
> > characters into their ASCII equivalents.
> 
> (AFAIK)
> 
> Only ASP.NET/IIS decodes that automatically.
> 
> PHP *can* do that as like JSP and probably others but that has
> to happen explicitly in the application code or on an other layer.
> 
> Regards,
> Francesco `ascii` Ongaro
> http://www.ush.it/
> 
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------- End of Original Message -------



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