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Re: Snort 2.9.0.1 Now Available
From: L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com>
Date: Mon, 8 Nov 2010 11:11:48 -0600

Hello.  Unfortunately I cannot provide pcap but I hoped to provide
enough info so that it could be reproduced.

Eoin:  I saw your email and read your blog post when it came out ... I
was just hoping that snort version 2.9.0.1 fixed the issues with the
HTTP pre-processor and reassembly since Steve Sturges indicated it did
but maybe he is referring to other fixes???

-L0rd C.

On Mon, Nov 8, 2010 at 10:54 AM, Russ Combs <rcombs () sourcefire com> wrote:
Can you send us a pcap?

On Mon, Nov 8, 2010 at 11:45 AM, L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com>
wrote:

Hello.

I am still experiencing HTTP stream reassembly issues when trying to
match across multiple fragmented packets with snort 2.9.0.1.

Specifically, this happens on a HTTP POST where the headers are in a
different packet than the POST data. Consider the following rule you
can use along with scapy to reproduce if you want:

alert tcp any any -> $HOME_NET $HTTP_PORTS (msg:"Incoming German POST
to Batman"; flow:established,to_server; content:"POST"; http_method;
uricontent:"/batcave/"; uricontent:"unicorns4sourcefire"; content:"|0d
0a|Accept-Language: de"; nocase; http_header; content:!"|0d 0a 0d
0a|not4batman=true&"; content:!"\; batsecret=sesstoken4robin";
http_cookie; classtype:trojan-activity; sid:8008135; rev:17;)

It alerts (b/c all the URI and HTTP header stuffs match in the initial
packet) but it shouldn't alert b/c the HTTP POST data starts with
'not4batman=true&' (but the POST data is in a subsequent packet than
the one containing the headers).

Anyone else still having issues or have done more in-depth testing
with 2.9.0.1 and the HTTP pre-processor?

-L0rd C.

On Tue, Nov 2, 2010 at 5:34 PM, Steven Sturges
<steve.sturges () sourcefire com> wrote:
There was an issue in that HTTP inspect wasn't correctly handling
raw vs. stream reassembled packets when looking at HTTP response
data.  This fix is included in 2901 -- refer to ChangeLog (changes
to hi_client.c/hi_server.c).

As to the support of 2.8.6, with the release of 2.9.0, 2.8.6.x
is no longer supported.  When there is a new "3 digit" release no
further patches are made to the previous version of Snort.

On 11/1/2010 1:05 PM, L0rd Ch0de1m0rt wrote:
Hello. Does this release fix the issue where the HTTP pre-processor
wasn't properly examining reassembled data across fragmented packets?
(I don't know the exact cause of the bug - maybe it was the other way
around and Stream5 wasn't properly doing the reassebly.)  It was
announced that there would be a patch for that issue, just want to see
if this is it.  If so, when can we expect the 2.8.6.1 patch be
released?  2.8.6.1 is still supported, right?

Thanks!

-L0rd C.


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