Snort mailing list archives

Re: Local rules with same sids and snort works!


From: fatema bannatwala <fatema.bannatwala () gmail com>
Date: Wed, 9 Nov 2016 13:40:40 -0500

Well, the rules have same rev numbers, and the order is like this:

alert tcp $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (msg:"HTTP Proxy
client detected"; flow: to_server,established; content:"X-Forwarded-";
http_header; reference:url,http:/           /
www.forensicswiki.org/wiki/Proxy_server; classtype:policy-violation;
sid:10001030; rev:1;)

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Custom Likely
Successful Generic Phish 2016-09-23"; flow:to_server,established;
content:"POST"; http_method; content:".php"; http_uri; content:"netid=";
depth:10; fast_pattern; http_client_body; content:"&pword="; distance:0;
classtype:trojan-activity; sid:10001030; rev:1;)

I only get alerts from the second one now, i.e phishing one, and haven't
gotten any alert triggered for the first rule.
Previously, when I had only the first rule, I used to get lot of alerts for
people using proxy, but ever since the second alert got added I realized
that the first rule stopped triggering anymore.

On Wed, Nov 9, 2016 at 1:28 PM, Joel Esler (jesler) <jesler () cisco com>
wrote:

You can have duplicate SIDS.  The rule with the highest rev will override
the lower rev rule, otherwise Snort will take the first rule it gets to,
and ignore the other one.

It’s been this way for several years.


*--*
*Joel Esler *| *Talos:* Manager | jesler () cisco com






On Nov 9, 2016, at 1:19 PM, fatema bannatwala <fatema.bannatwala () gmail com>
wrote:

Hi All,

Just realized that I have two rules in my local.rules file with same sid,
and snort works just fine!!
I always had in my head that sids should have to be unique, but today when
I was going through the local.rules file, I realized that someone from our
team had created a new rule and assigned it a same sid that a previous rule
had.
I couldn't catch it before because snort was running just fine without any
complains on duplicate sids.

Have I missed this change in the current (or 2.9 version) of snort or is
it something else?

Quick points: I have local.rules enabled in snort.conf and pulled pork is
not modifying anything regarding local rules so they should get loaded as
it is, and above all I am getting alerts for one of the rules having
duplicate sid, but no alerts for the other rule having same sid.

Snort version - 2.9.8.3
barnyard version - 2-1.9
pulledpork - 0.7.0

Thanks,
Fatema.
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Developer Access Program for Intel Xeon Phi Processors
Access to Intel Xeon Phi processor-based developer platforms.
With one year of Intel Parallel Studio XE.
Training and support from Colfax.
Order your platform today. http://sdm.link/xeonphi
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