[Snort-sigs] Snort Rule Creation

John G drterdnugget at ...2420...
Tue Jan 31 20:27:54 EST 2017


Alright, so this is basically what I did.

Alert ip !SOURCEIP any [8, Destination, IP's] any (msg:”Unauthorized TCP
traffic initiated”;)

I figured out that you can negate with ! in front of the IP's.  To test it,
I have been sending ping packets to the destination IP's from a source ip
address that is NOT what i entered in the Source IP part of the rule.
However, I am not receiving any alerts.  Do i need to add arguments to look
for tcp traffic?

On Tue, Jan 31, 2017 at 5:58 PM, John G <drterdnugget at ...2420...> wrote:

> Forgot to attach the screenshot.
>
> On Tue, Jan 31, 2017 at 5:09 PM, Joel Esler (jesler) <jesler at ...3865...>
> wrote:
>
>> Maybe something like:
>>
>> alert tcp $SOURCEIP any -> ![destip1, destip2, destip3] any
>> (msg:”Unauthorized TCP traffic initiated”; flags:S; sid:1000000; rev:1;)
>>
>>
>> ?
>>
>>
>> *--*
>> *Joel Esler *| *Talos:* Manager | jesler at ...3865...
>>
>>
>>
>>
>>
>>
>> On Jan 31, 2017, at 5:33 PM, John G <drterdnugget at ...2420...> wrote:
>>
>> Good Afternoon everyone,
>>
>> My name is John and I am starting out with creating Snort rules.  I have
>> experience using Snort with IDS's such as Sourcefire and Security Onion for
>> incident response.  However, i don't have much experience creating custom
>> rules.  Although i once created a rule during one of my security classes
>> during my undergrad program lol  Anyway, i have been reading documentation
>> for how to understand/create rules from a variety of sources.  But I wanted
>> to reach out to you guys and see what information you can provide.
>>
>> I have a device that is communicating with about 8 other devices.  I
>> would like to write a rule that alerts if it detects any communication
>> outside of those devices.
>>
>> Is it possible to list multiple ip addresses within a rule and maybe use
>> an is not "!=" attribute.
>>
>> So something like: alert tcp != sourceip1  80 -> destip1, destip2,
>> destip3, etc (msg:"Alert Message";)
>>
>> I would appreciate any assistance and will continue to do my own research
>> and see if i can figure it out on my own :)
>>
>> Regards,
>> John
>> ------------------------------------------------------------
>> ------------------
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>>
>>
>
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