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Re: Sourcefire VRT Certified Snort RulesUpdate2010-03-17

From: "evilghost () packetmail net" <evilghost () packetmail net>
Date: Tue, 23 Mar 2010 19:58:07 -0500
Judging from Joel's response evidently Mike is spot-on, which just 
caused my jaw to drop.  Are you serious?  You seriously didn't support 
gzip encoded data until 2.8.6?  I'm really trying to refrain from using 
profanity here.  The deeper and deeper the community digs the more and 
more Sourcefire gets exposed as the snake-oil salesmen they really are.

I'm sure that statement will ruffle your feathers but take a step back.  
How the heck can you claim to protect this, lead this, #1 this, look the 
security community in the eye and peddle your product, and not handle 
HTTP/1.1 gzip encoding?!? (look, you even caused me to use excessive 
punctuation)

That's fscking pathetic.  Modern HTTPDs don't seem to have issues 
managing gzip encoding.  "Processing power" being the excuse for not 
implementing this is equally as pathetic.  I really hope Joel is wrong here.

I'm sure some of you SF guys are gnashing your teeth and shaking your 
fists but take a step back and think about this.  Not supporting gzip 
encoding?  Seriously?  Since I've grown acustom to the dangling carrots 
which tend to rot how about a new feature in the upcoming "Wiki" titled 
"Glaring Limitations You Should Be Aware Of".  We'll add SMP support, 
gzip encoding (pre 2.8.6), and more.

Label me as a troll if you wish but when your bridge is made out of 
straw it's pretty easy to get eaten.  Be sure to tell me you're an Open 
Source/Community friendly solution too.  I'm not sure who I really need 
to protect my network from, Sourcefire or the attackers.

-evilghost

Joel Esler wrote:

This is a difficult thing to do, as it requires some good processing 
power to be able to do this. 

--
Joel Esler
Sent from my iPhone

On Mar 23, 2010, at 6:41 PM, Mike Cox <mike.cox52 () gmail com 
<mailto:mike.cox52 () gmail com>> wrote:


Wait ... the http_inspect preprocessor didn't decode gzip and match 
against the unzipped data until 2.8.6 (and/or 2.8.5)?  If so, this 
should have been put in 5+ years ago.  I could be making a false 
assumption here which I probably am because I can't imagine that 
snort didn't do this before now....

-Mike Cox

On Tue, Mar 23, 2010 at 5:27 PM, Joel Esler <joel.esler () me com 
<mailto:joel.esler () me com>> wrote:

    Will,

    I'm not saying that 2.8.6 will solve these problems, but it
    definitely will help.  For example the following is new
    functionality (and/or keywords) either in recent versions of
    2.8.5 or within Snort 2.8.6.

    (This information comes out of the Snort Manual)

    http_client_body -- The http client body keyword is a content
    modifier that restricts the search to the body of an HTTP client
    request.
    http_cookie -- The http cookie keyword is a content modifier that
    restricts the search to the extracted Cookie Header field of a
    HTTP client request or a HTTP server response
    http_raw_cookie -- The http raw cookie keyword is a content
    modifier that restricts the search to the extracted UNNORMALIZED
    Cookie Header field of a HTTP client request or a HTTP server
    response
    http_header -- The http header keyword is a content modifier that
    restricts the search to the extracted Header fields of a HTTP
    client request or a HTTP server response
    http_raw_header -- The http raw header keyword is a content
    modifier that restricts the search to the extracted UNNORMALIZED
    Header fields of a HTTP client request or a HTTP server response
    http_method -- The http method keyword is a content modifier that
    restricts the search to the extracted Method from a HTTP client
    request.
    http_uri -- The http uri keyword is a content modifier that
    restricts the search to the NORMALIZED request URI field . Using
    a content rule option followed by a http uri modifier is the same
    as using a uricontent by itself
    http_raw_uri -- The http raw uri keyword is a content modifier
    that restricts the search to the UNNORMALIZED request URI field
    http_stat_code -- The http stat code keyword is a content
    modifier that restricts the search to the extracted Status code
    field from a HTTP server response.
    http_stat_msg -- The http stat msg keyword is a content modifier
    that restricts the search to the extracted Status Message field
    from a HTTP server response.
    http_encode -- The http encode keyword will enable alerting based
    on encoding type present in a HTTP client request or a HTTP
    server response

    We also have the ability to uncompress the compressed data in
    gzip in http_inspect now:
    inspect_gzip: This option specifies the HTTP inspect module to
    uncompress the compressed data (gzip/deflate) in HTTP response.

    Just some of the new options.

    Joel

    On Mar 23, 2010, at 6:16 PM, Will Metcalf wrote:

    > Joel,
    >
    > What of these potential evasions are addressed specifically by
    2.8.6?
    > Unless snort has made fundamental changes to the way it operates I
    > think these issues will be very difficult to overcome but as I
    said,
    > these are not snort specific issues. There is a reason why most
    NIDS's
    > commercial or otherwise are blind to this stuff, it's because
    > client-side is a really freaking hard problem to solve.  This is
    > especially true at multi-gigabit speeds, even if you are sporting
    > latest 32 core xeon 55xx server or something.
    >
    > Regards,
    >
    > Will
    > On Tue, Mar 23, 2010 at 4:51 PM, Joel Esler <joel.esler () me com
    <mailto:joel.esler () me com>> wrote:
    >> I would encourage a look at the new http_inspect in 2.8.6.
    >>
    >> --
    >> Joel Esler
    >> Sent from my iPhone
    >>
    >> On Mar 23, 2010, at 5:11 PM, Will Metcalf
    <william.metcalf () gmail com <mailto:william.metcalf () gmail com>> wrote:
    >>
    >>>> 1) sid:15013 will only set the flowbit if I download the PDF
    from a
    >>>> webserver (alert tcp $HOME_NET any -> $EXTERNAL_NET
    $HTTP_PORTS).
    >>>> What if the malicious pdf is sent via email -- or another
    method?
    >>>> 16490 will never even run because the flowbit is not set.  
    Right?
    >>>>
    >>>> 2) From sid:16490, I gather that it will only trigger if the
    malicious
    >>>> PDF communicates with an external webserver on an HTTP_PORT
    and the
    >>>> exploit is then sent from that server (alert tcp $EXTERNAL_NET
    >>>> $HTTP_PORTS -> $HOME_NET any -- flow to server).  Is that
    correct?
    >>>> What if the malicious PDF is configured to communicate on a non
    >>>> HTTP_PORT with the malicious webserver.
    >>>
    >>> Or if encryption is used, or if the client side exploit isn't
    >>> contained within the first x bytes of the payload you have
    configured
    >>> for flow_depth, or if the client side exploit can be encoded in
    >>> javascript, etc. etc. etc.  This isn't a snort specific
    problem all
    >>> network based IDS's suck at detecting client-side exploits.
     They just
    >>> aren't the right tool for the job, despite what your vendor
    my share
    >>> with you via their marketing slides ;-).
    >>>
    >>>> This brings me to a question.   What are most of you doing for
    >>>> 443/tcp.  Do you include it in your HTTP_PORTS variable or
    not?   By
    >>>> default I believe it is NOT included.   Wouldn't this mean that
    >>>> another really easy way to avoid detection of this particular
    >>>> vulnerability being exploited would be to have your
    malicious pdf
    >>>> connect to port 443 instead of 80 outbound?  (In metasploit,
    setting
    >>>> LPORT to anything aside from 80?)
    >>>
    >>> But you are filtering egress traffic right?  And using a proxy to
    >>> enforce protocol behavior right?  Also you have sort of
    ASLR/buffer
    >>> overflow type protection on your clients right? Via some Host IPS
    >>> product or something like EMET?
    >>>
    >>>
    >>>
    http://www.microsoft.com/downloads/details.aspx?FamilyID=4a2346ac-b772-4d40-a750-9046542f343d&displaylang=en
    <http://www.microsoft.com/downloads/details.aspx?FamilyID=4a2346ac-b772-4d40-a750-9046542f343d&displaylang=en>
    >>>
    >>> Regards,
    >>>
    >>> Will
    >>>
    >>>
    >>>
    ------------------------------------------------------------------------------
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    --
    Joel Esler
    http://blog.joelesler.net



    ------------------------------------------------------------------------------
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    See why Intel Parallel Studio got high marks during beta.
    http://p.sf.net/sfu/intel-sw-dev
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------------------------------------------------------------------------

------------------------------------------------------------------------------
Download Intel&#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev
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------------------------------------------------------------------------------
Download Intel&#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev
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