Snort mailing list archives

Re: [SUSPECTED SPAM] snort3.0 doesn't log the triggering packet of an alert


From: Russ <rucombs () cisco com>
Date: Mon, 9 Jan 2017 09:03:01 -0500



On 1/9/17 2:53 AM, Maxim wrote:
Hi Albert,
In seciont 1.3.2 of snort3.0 manual,  there is a saying:
"-A u2 is the same as -A unified2 and will log events and triggering packets in a binary file that you can feed to other tools for post processing. Note that Snort 3 does not provide the raw packets for alerts on PDUs; you will get the actual buffer that alerted. "
I think it does something to do with this. Am I right?
Correct. We can try to provide more information. Please describe the info you need and how you use it. In general, raw packets aren't terribly helpful, but we could log other buffers as well.

Hittlle




At 2017-01-09 11:46:42, "Maxim" <hittlle () 163 com> wrote:

    Hi Albert,
    It is the HTTP request packet that fires the alert, so this packet
    should be recorded, right? And all packets in the same session
    after this offensive request packet should be logged, right? Many
    thanks.





    At 2017-01-07 06:37:19, "Al Lewis (allewi)" <allewi () cisco com
    <mailto:allewi () cisco com>> wrote:

        You can capture the session traffic with just the tagging.

        I don’t think your problem is with the session/tagging
        functionality. You need to create a rule that alerts THEN
        starts recording.

        Snort will not be able to go back and capture packets BEFORE
        the rule alerted. So if you have a rule that alerts on a
        response packet Snort will not be able to go back and
        “recapture” the request or packets that happened BEFORE the alert.

        See attached. It uses a telnet session to alert on the SYN
        flag, then logs traffic for the next second.

        I ran snort like this

        "snort -c etc/snort/maxim.lua -r etc/snort/maxim.pcap -k none
        -l . “

         which produced the pcap, alert, codec and unified log files.


        Hope this helps.

        *Albert Lewis*

        ENGINEER.SOFTWARE ENGINEERING

        SOURCE*fire*, Inc. now part of *Cisco*

        Email: allewi () cisco com <mailto:allewi () cisco com>


        From: Maxim <hittlle () 163 com <mailto:hittlle () 163 com>>
        Date: Thursday, January 5, 2017 at 9:41 PM
        To: allewi <allewi () cisco com <mailto:allewi () cisco com>>
        Cc: 'snort-users' <snort-users () lists sourceforge net
        <mailto:snort-users () lists sourceforge net>>
        Subject: Re:Re: [SUSPECTED SPAM] [Snort-users] snort3.0
        doesn't log the triggering packet of an alert

        Hi Albert,
        Thanks for your help. Attached please kindly find my
        snort.lua. My question is not that snort doesn't record any
        packets to unified2 file, but the first packet that triggeres
        the alert. What I am doing is this: if a packet fire a rule,
        tell snort to record the bidirectional packets (packets
        belonging to the same session) of that session. So, I write
        the following rule:

                     alert tcp any any -> any 80 (
        msg:"test-http-req-body"; content:"abc";http_client_body;
        flowbits:isnotset,105;flowbits:set,105;tag:session;sid:
        105;rev:1;)

        As you can see, I used flowbits and tag:session to accomplish
        this. And ran snort this way:
                    /opt/snort3.0/bin/snort -c
        /var/log/snort/snort.lua -i eth0 -D -l /var/log/snort/

        As you can see from the attached unified2 log file, I can see
        the alert, and the HTTP response packet. But I cannot find the
        request packet payload information there. Am I missing
        something here? Thanks.





        At 2017-01-05 19:17:23, "Al Lewis (allewi)" <allewi () cisco com
        <mailto:allewi () cisco com>> wrote:

            Hello Maxim,

            Please see the section under the snort3 manual for loggers:

            
https://s3.amazonaws.com/snort-org-site/production/release_files/files/000/004/860/original/snort_manual.html?AWSAccessKeyId=AKIAIXACIED2SPMSC7GA&Expires=1483618124&Signature=4RZ4GTblHk9jmFlDhjHddxo%2BA28%3D#_logger_modules


            Its impossible to say what the issue is without a copy of
            your configuration.

            Attached is a basic config that should log any tcp packet.

            All I did was run it with this below:

            ./bin/snort -c etc/snort/maxim.lua -r
            /home/alewis/Downloads/CURL.pcap -l .


            And it produced log files as these (unified log is there):


            alewis@box3:/var/tmp/snort++$ ls
            alert_full.txt  bin  core  etc  include  lib
             log_codecs.txt  share  unified2.log
            alewis@box3:/var/tmp/snort++$


            *Albert Lewis*

            ENGINEER.SOFTWARE ENGINEERING

            SOURCE*fire*, Inc. now part of *Cisco*

            Email: allewi () cisco com <mailto:allewi () cisco com>


            From: Maxim <hittlle () 163 com <mailto:hittlle () 163 com>>
            Date: Thursday, January 5, 2017 at 3:19 AM
            To: 'snort-users' <snort-users () lists sourceforge net
            <mailto:snort-users () lists sourceforge net>>
            Subject: [SUSPECTED SPAM] [Snort-users] snort3.0 doesn't
            log the triggering packet of an alert

            Hi snort experts,
                I just tried snort 3.0, and found that it doesn't log
            the triggering packet of an alert if I use unified2
            logger. Is it a bug or am I missing any required
            configurations? It's very different from snort 2.9.8.0.
            Many thanks.








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