[Oisf-users] false alerts?

Wed Mar 27 14:44:11 UTC 2013

On Wed, Mar 27, 2013 at 3:30 PM, Jose Paulo <paulo at sistemasolar.com.br>wrote:

>  Thank you Peter Manev.
>
> 1) Yes, it's correct. It's a pcap file captured at this time.
>
:) , understood.

> 2) Sorry, I can't. But I received authorization to post the alert-debug,
> if it help.
>
it will be a bit tough pinpointing/troubleshooting "blindly" why do you
have a problem.
You could share the alert-debug and/or the pcap privatelly if you would
like.
Also:
3) Which Suricata version are you running / the output of :
suricata --build-info
4) how do you start/run suricata?

would be helpful as well
Thanks

>
> Thanks again.
>
> José Paulo
>
>
> Le 27/03/2013 09:34, Peter Manev a écrit :
>
>
>
> On Wed, Mar 27, 2013 at 1:03 PM, Jose Paulo <paulo at sistemasolar.com.br>wrote:
>
>> Hello all.
>>
>> I'm studying Suricata and I got this result:
>>
>> 11/16/2011-15:00:00.198278  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:00:00.198278  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:00:09.374228  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:00:09.374228  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:00:09.374228  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:31.769957  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:38.380502  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:38.380502  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:44.609767  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:44.609767  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:44.609767  [**] [1:9000002:0] HEX offset 514 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000002:0] HEX offset 514 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>>
>> against this rules set:
>>
>> alert tcp any any <> any 23 (msg:"HEX no offset "; content: "|F8 F8 F8
>> F8 40 C3 81 89 A7 81|"; sid:9000001;)
>> alert tcp any any <> any 23 (msg:"HEX offset 514"; content: "|F8 F8 F8
>> F8 40 C3 81 89 A7 81|"; offset:514; sid:9000002;)
>> alert tcp any any <> any 23 (msg:"HEX offset 516"; content: "|F8 F8 F8
>> F8 40 C3 81 89 A7 81|"; offset:516; sid:9000003;)
>> alert tcp any any <> any 23 (msg:"HEX offset 510"; content: "|F8 F8 F8
>> F8 40 C3 81 89 A7 81|"; offset:510; sid:9000004;)
>> alert tcp any any <> any 23 (msg:"HEX offset 503"; content: "|F8 F8 F8
>> F8 40 C3 81 89 A7 81|"; offset:503; sid:9000005;)
>>
>> My doubts are:
>>
>> 1) Why I'm getting alerts for sid's 9000004,5 for the same packet if the
>> offset is shifted?
>>
>> 11/16/2011-15:01:48.726883  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000002:0] HEX offset 514 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>>
>> 2) Why I'm not getting alerts for sid 9000001 if I got for the others?
>>
>> 11/16/2011-15:01:44.609767  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:44.609767  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:44.609767  [**] [1:9000002:0] HEX offset 514 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>>
>> The expected result is only this:
>> 11/16/2011-15:00:09.374228  [**] [1:9000004:0] HEX offset 510 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:00:09.374228  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:38.380502  [**] [1:9000005:0] HEX offset 503 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:38.380502  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000002:0] HEX offset 514 [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>> 11/16/2011-15:01:48.726883  [**] [1:9000001:0] HEX no offset  [**]
>> [Classification: (null)] [Priority: 3] {TCP} 10.31.15.32:23 ->
>> 10.85.185.2:43569
>>
>> I don't understand why the others occurs.
>> Any enlightenment will be welcome.
>>
>> Best regards!
>>
>> José Paulo
>>
>> _______________________________________________
>> Suricata IDS Users mailing list: oisf-users at openinfosecfoundation.org
>> Site: http://suricata-ids.org | Support: http://suricata-ids.org/support/
>> List: https://lists.openinfosecfoundation.org/mailman/listinfo/oisf-users
>> OISF: http://www.openinfosecfoundation.org/
>>
>
>
> Hi,
> A couple of questions:
> 1) 11/16/2011- is that really the time in the current packets?
> 2) Can you share a pcap , if that is ok?
>
> Thank you
>
>
>
> --
>  Regards,
> Peter Manev
>
>
>
> _______________________________________________
> Suricata IDS Users mailing list: oisf-users at openinfosecfoundation.org
> Site: http://suricata-ids.org | Support: http://suricata-ids.org/support/
> List: https://lists.openinfosecfoundation.org/mailman/listinfo/oisf-users
> OISF: http://www.openinfosecfoundation.org/
>

-- 
Regards,
Peter Manev
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