Re: Signature Lookup Confusion

[waldo kitty <wkitty42 () windstream net>]

On 5/7/2013 13:24, Josh Bitto wrote:
> I'm having a bit of a problem fully grasping how to search up rules that have
> been fired.....
>
> 2013-05-07T10:14:05-07:00 firewall snort[62223]: [120:8:1] (http_inspect)
> INVALID CONTENT-LENGTH OR CHUNK SIZE [Classification: Unknown Traffic]
> [Priority: 3] {TCP} 209.97.200.53:32459 ->  216.178.47.38:80
>
>
> Ok so what I understand from the log is that rule 120 fired. Either I need

no sir... rule identifiers are in GID:SID:rev format... only the GID:SID are 
really necessary...

the above says Generator 120 fired its rule with SID 8...

Generator 120 is http_inspect...

its rule SID 8 is "INVALID CONTENT-LENGTH OR CHUNCK SIZE"...

these are not "normal" rules like the *.rules files you download... these rules 
are built into the processor...

> some caffeine or it's a horrible Tuesday for me to comprehend this, but I'm
> just not getting it. The instructions on how to search for the group id and
> the sid for some reason are not sticking. Can someone dumb this down for
> me....I'm gonna run out and get a pop and hopefully come back to someone who
> has awesomely helped me out.

does the above help?

> Basically I want to be able to search for explanations on whatever event
> happens so I can determine if I need to take action or not.

this is where you might need to break out a pcap viewing tool like wireshark so 
you can look at the content of the network traffic that triggered the rule... 
snort should have saved a pcap for you and this particular entry will likely be 
inside a large pcap containing other saved traffic from other alerts... you use 
the timestamp to determine the proper packet to look at and then work it from 
there...


FWIW: i've someone who is a client on a large Canadian cable network and they 
are getting hit by tons of these... we haven't yet determined why, though...

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