[Oisf-devel] small pb (FN) on suricata with content and offset+depth

rmkml rmkml at free.fr
Fri May 21 14:19:01 UTC 2010


Thx again for reply Will,
I have opened ticket #164.
Regards
Rmkml


On Fri, 21 May 2010, Will Metcalf wrote:

> Confirmed.  This is a bug. The first sig should fire given the attached pcap.
>
> Regards,
>
> Will
>
> On Fri, May 21, 2010 at 5:27 AM, rmkml <rmkml at free.fr> wrote:
>> and if anyone confirm, Im open a ticket...
>> Rmkml
>>
>>
>> On Fri, 21 May 2010, rmkml wrote:
>>
>>> Hi,
>>> I have a small pb with this sig and joigned (dns/udp) pcap file without alert
>>> firing:
>>> alert udp any 53 -> any any (msg:"suricata test dns reply"; content:"|00 00
>>> 00|"; offset:3; depth:4; classtype:bad-unknown; sid:9199437; rev:1;)
>>> simplified tcpdump hex output (on joigned pcap file):
>>> 0x0000:  4500 0028 0000 4000 3411 5152 c202 2809
>>> 0x0010:  0a32 0136 0035 e6e6 0014 1a16 6098 a888
>>> 0x0020:  0000 0000 0000 0000 0000 0000 0000
>>> ok udp payload start at 0x1c, on my sig, offset:3 start at 0x1f, but depth:4
>>> allow me 0x1f:88 + 0x20:00 + 0x21: 00 + 0x22:00.
>>> Anyone confirm this small pb please?
>>> Tested on suricata v0.9.0 and git on date 20 may 2010
>>> (b629b7c5c1e2ad6c91b97b6708ad9ddc6a674502).
>>>
>>> and of course, this sig work:
>>> alert udp any 53 -> any any (msg:"suricata test dns reply"; content:"|00 00
>>> 00|"; offset:4; depth:3; classtype:bad-unknown; sid:9199437; rev:1;)
>>> Regards
>>> Rmkml
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>


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