Re: FP shows snort-2.9.0.3 confused over packets and sessions

[rmkml <rmkml () yahoo fr>]

Hi Jason,
I suggest replace `depth:4;` to `http_method;`.
Replace it's work on my test.
I have another suggest, replace `isdataat:200,relative;` to `isdataat:200,relative; content:!"|0A|"; within:200;`.
I have another another suggest, on pcre, replace `(?!\n)` to `(?!\r?\n)`.
Please upgrade to snort v2.9.0.5.
Regards
Rmkml


On Tue, 10 May 2011, Jason Haar wrote:

> Hi there
> This rule just FP'ed here on a user POSTing something. The rule says
> alert tcp $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"WEB-MISC
> Sun Java Web Server Webdav Stack Buffer Overflow attempt";
> flow:to_server,established; content:"COPY"; depth:4; nocase;
> isdataat:200,relative; pcre:"/^COPY(?!\n)\s[^\n]{200}/smi";
> metadata:policy balanced-ips drop, policy security-ips drop, service
> http; reference:bugtraq,37874; reference:cve,2010-0361;
> classtype:attempted-admin; sid:17609; rev:1;)
> ..but somehow it triggered on a packet (going through a proxy if it
> matters) that the snort PCAP states begins with
>  copy to blah-blah-blah.....
> It seems to me this has matched on the beginning of  a *packet* instead
> of the beginning of a TCP *session*? What should I be looking at to fix
> this? I assume I've got something amiss in stream5 or something? As I
> said, I've checked the proxy logs and that was a POST command of 2178
> bytes. No HTTP headers/etc shows up in this captured packet - so I'd say
> it was the 2nd data packet in the  TCP session
> Thanks
> -- 
> Cheers
>
> Jason Haar
> Information Security Manager, Trimble Navigation Ltd.
> Phone: +64 3 9635 377 Fax: +64 3 9635 417
> PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1

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