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

Will Metcalf william.metcalf at gmail.com
Fri May 21 14:40:41 UTC 2010


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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