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Old 05-03-2008, 11:36 PM   #1
abefroman
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How many alerts a day do you get on snort?


How many alerts a day do you get on snort?

I know I'm getting way too many and want to optimize, but I don't want to optimize too much.

How many alerts/day should I try to get it down to?
 
Old 05-04-2008, 07:24 AM   #2
unSpawn
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Quote:
Originally Posted by abefroman View Post
How many alerts a day do you get on snort?
Ranging from a few to a few hundred.


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Originally Posted by abefroman View Post
I know I'm getting way too many and want to optimize, but I don't want to optimize too much. How many alerts/day should I try to get it down to?
I think your aim should not be to bring the amount of alerts down (quantity) but what it trips on (quality).
First prune rulesets that you don't need (anything P2P, etc, etc). Log for a while. Then assess which services are exposed to world and should need watching, then gather statistics to see what it trips on. Correlate stats with services and prune rules further (MS-.*, Solaris, Websphere). Then add a BPF filter for services that need watching but are accessed from "trusted" ranges if it trips on that. Log for a while. Search logs for false positives and also see threshold.conf for alert/warn ratios.
 
Old 05-04-2008, 06:19 PM   #3
abefroman
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Quote:
Originally Posted by unSpawn View Post
Ranging from a few to a few hundred.



I think your aim should not be to bring the amount of alerts down (quantity) but what it trips on (quality).
First prune rulesets that you don't need (anything P2P, etc, etc). Log for a while. Then assess which services are exposed to world and should need watching, then gather statistics to see what it trips on. Correlate stats with services and prune rules further (MS-.*, Solaris, Websphere). Then add a BPF filter for services that need watching but are accessed from "trusted" ranges if it trips on that. Log for a while. Search logs for false positives and also see threshold.conf for alert/warn ratios.
Thanks! I did my first batch of pruning and am letting it run a while now.

Can you give an example of one of the rules I should be concerned about if I see?

Either from Emerging Threats or one of the Snort VRT rules.
 
Old 05-04-2008, 09:03 PM   #4
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Can you give an example of one of the rules I should be concerned about if I see?
Whatcha running Willis?
 
Old 05-04-2008, 10:27 PM   #5
abefroman
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Whatcha running Willis?
Apache, php, mysql, ssh, pop, exim
 
Old 05-05-2008, 07:35 AM   #6
unSpawn
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What runs on top of PHP? Are those services all exposed to world w/o access restrictions?
 
Old 05-05-2008, 10:52 AM   #7
abefroman
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What runs on top of PHP?
>>You name it, its running

Are those services all exposed to world w/o access restrictions?
>>Yes

Here are my top 10 alerts over about 12 hours, are these any to be concerned with?
http://abefroman.com/topten.html

Last edited by abefroman; 05-05-2008 at 11:26 AM.
 
Old 05-06-2008, 08:53 AM   #8
unSpawn
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Quote:
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Are those services all exposed to world w/o access restrictions?
>>Yes
Why does the whole world need access to MySQL, SSH, POP, MTA? Is this an ISP machine?


Quote:
Originally Posted by abefroman View Post
Here are my top 10 alerts over about 12 hours, are these any to be concerned with?
You can follow those "Snort" links to learn more about what that sig matches. If it matches a regular GET request for instance you know it's not.
 
  


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