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Re: New Snort Bypass - Patch - Bypass of Patch



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@xxxxxxx> 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