Dailydave mailing list archives
RE: Testing the quickness of signature writers
From: "Dave Korn" <dave.korn () artimi com>
Date: Tue, 2 May 2006 15:44:36 +0100
On 02 May 2006 15:39, Dave Aitel wrote:
Brian Caswell wrote:
alert tcp $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"WEB- PHP horde help module arbitrary command execution attempt"; flow:established,to_server; uricontent:"/services/help/"; pcre:"/[\? \x3b\x26]module=[a-zA-Z0-9]*[^\x3b\x26]/U"; classtype:web-application- attack;)
Does your script break if I shove a space in between the \x3b and the \x26? I try to understand snort signatures, but they're essentially optimized to be exactly the opposite of what my brain can handle. PCRE is here
http://www.snort.org/docs/snort_manual/node21.html#SECTION00451000000000000000 0
but maybe I'm not seeing it right.
pcre:"/[\? \x3b\x26]module=[a-zA-Z0-9]*[^\x3b\x26]/U";
A forward slash, followed by any one char from the set ('?', ';', '&') followed by the literal text "module=" followed by any number (zero or more) alphanumerics followed by any char that is neither ';' nor '&'. All matched against the decoded URI buffer. I.e. it's looking at the url-encoded cgi parameters (which always follow a ? ; or &) for one that matches 'module=.....something...' and making sure that the bit after the equals sign has only alphanums until it meets the delimiter which identifies the next field. cheers, DaveK -- Can't think of a witty .sigline today....
Current thread:
- Testing the quickness of signature writers Dave Aitel (May 01)
- Re: Testing the quickness of signature writers Brian Caswell (May 01)
- Re: Testing the quickness of signature writers Dave Aitel (May 02)
- RE: Testing the quickness of signature writers Dave Korn (May 02)
- RE: Testing the quickness of signature writers M. Shirk (May 02)
- Re: Testing the quickness of signature writers Dave Aitel (May 02)
- Re: Testing the quickness of signature writers Brian Caswell (May 02)
- RE: Testing the quickness of signature writers Dave Korn (May 02)
- Re: Testing the quickness of signature writers Dave Aitel (May 02)
- Re: Testing the quickness of signature writers Brian Caswell (May 01)
- Re: Testing the quickness of signature writers Brian Caswell (May 02)