From: xxradar (xxradar@radarhack.com)
Date: Wed Sep 26 2007 - 14:16:00 EDT
Hi,
I've seen some firewalls that support inspection of fragmented traffic, but
it does not mean they reassemble the traffic. This should be done at the
endpoint (host or server, or proxy).
I agree that it becomes more difficult to 'fool' firewalls or IPS/IDS with
fragmentation, but myself I had a lot of success with fragroute to bypass
IDS/IPS systems that were able to decrypt SSL traffic. Very few (not to say
none ...) were able to handle fragroute. If they already succeeded to
support IP fragmentation, they certainly messed up when using the TCP
segmentation features present in fragroute.
Regards,
----------------------------------------------------------------------------
---------------------------------
Philippe Bogaerts
mailto:xxradar@radarhack.com
http://www.radarhack.com
http://blog.securityprofessional.be/
http://www.linkedin.com/in/xxradar
NEW http://www.radarhack.com/dir/papers/Getting started with OWASP WebGoat
4.0 and SOAPUI.pdf
-----Original Message-----
From: listbounce@securityfocus.com [mailto:listbounce@securityfocus.com] On
Behalf Of Shenk, Jerry A
Sent: Wednesday, September 26, 2007 1:06 PM
To: seclt yuri; Harry Hoffman
Cc: pen-test@securityfocus.com
Subject: RE: Are Fragmentation Attacks Still Used for IDS/IPS Evasion?
Well, like almost any security vulnerability, attacks against it are
useless unless it works! There are all kinds of "old attacks" that end
up being valid attack vectors all the time. You have no idea if people
have designed the network you are testing correctly or not.
One other point here - fragmentation attacks and what can get as a
result is something that you might want to test in your lab. If you
test it in a controlled environment, you will be better able to know if
it's working and what you can expect to gain when you use it in the
field.
-----Original Message-----
From: listbounce@securityfocus.com [mailto:listbounce@securityfocus.com]
On Behalf Of seclt yuri
Sent: Tuesday, September 25, 2007 10:29 PM
To: Harry Hoffman
Cc: pen-test@securityfocus.com
Subject: Re: Are Fragmentation Attacks Still Used for IDS/IPS Evasion?
Yes but this effectively means that fragmentation
attacks are useless if launched across the 'Net and
when performing a penetration test without local
access.
Also, even internal host systems are usually
segregated from servers and server vlans by a
firewall, so even then, I can't see how fragmentation
attacks would be effective. The only scenario that I
can think of would be within the same subnet or vlan
where traffic doesn't pass through a firewall.
Please correct me if I am wrong. Thank you.
--- Harry Hoffman <hhoffman@ip-solutions.net> wrote:
> yep, unfortunately not enough people using host
> based firewalls and alot
> of attacks happen inside of where the firewall
> protects (i.e. local lan)
>
> seclt yuri wrote:
> > Hi,
> > I was just reading up on fragmentation attacks
> using
> > fragrouter and fragrouter as a mean of IDS/IPS
> > evasion. However, since almost all firewalls both
> > commercial and free (iptables for examples) now
> have
> > support for fragment reassembly, are fragmentation
> > attacks still effective? Thanks.
> >
> >
> >
> >
>
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