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Network Security Snort-Signatures
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Re: [Snort-sigs] Strange PCRE usage in standard snort rules

Subject: Re: [Snort-sigs] Strange PCRE usage in standard snort rules
Date: Mon, 9 May 2005 04:48:21 -0700
On Mon, May 09, 2005 at 04:03:04PM +1000, Erik de Castro Lopo wrote:
OK, in order to resolve this ambiguity, I looked at the code.

code == docs   ;)


Therefore, if there are 27 non-newline characters, the DE will
then look for the string "&|00|" at exactly 29 bytes from the end 
of the PCRE match.

This means that the PCRE could be replaced with "/^[^\n]{27}/R",
but cannot be dropped altogether.

how about: 
        content: !"|0a|"; within:27;
        byte_test: 2,=,9728,56,big,relative;


-- 
Erik Fichtner; Unix Ronin

"Mathematics is something best shared between consenting adults
in the privacy of their own office" - Adam O'Donnell

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