Apache uses a modified version of the isspace() macro. So it allows
\f,\n,\r,\t (\v is not allowed, as far as I can recall) as whitespace.
I know this affected lot of IPSes.

Thanks,
Pukhraj

On 6/3/06, M. Dodge Mumford <dodge (at) nfr (dot) net [email concealed]> wrote:
> [Sorry to reply to my own post, but...]
>
> M. Dodge Mumford said:
> > Sigint Consulting said:
> > > perl -e 'print "GET \x0d/index.php\x90\x90 HTTP/1.0\n\r\n"'|nc
> > > 192.168.1.3 80
> > >
> > > No alert is generated from the string above.
> >
> > [...]
> >
> > > We are not sure how much this may buy an attacker as the CR character
> > > may mess up any requests to the webserver, further research is needed
> > > on this.
> >
> > I performed this research while developing NFR's web signatures, and found
> > that all web servers I tested (several years ago) handled end-of-lines using
> > "\x0d\x0a" and "\x0a" interchangeably. If you find a web server that
> > interprets "index.php" in the example above as an actual filename, I for one
> > would be very interested in knowing about it.
>
> Apparently my memory is failing. If I performed this test, I remembered the
> results incorrectly. Mea culpa.
>
>
> --
>
> Dodge
>
>
>

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