On 11/26/05, Stefano Di Paola <stefano.dipaola@wisec.it> wrote:
Hi Ivan,
Il giorno gio, 24-11-2005 alle 12:14 +0000, Ivan Ristic ha scritto:
Neither approach is good enough in real-life, when used on its own.
(Although there may be specific cases where they can work rather
well.)
yes no absolute rules can be implemented in real life...and i hope none
thinks this! And of course black list approach, which is the usual
approach on mod_sec, should not be considered as well...
Agreed. I will be adding explicit support for positive security to
ModSecurity in the next release. I have published my thoughts here
http://www.modsecurity.org/blog/archives/2005/11/positive_securi.html
so that we can discuss the issue.
I prefer a traffic based approach (for positive
security model generation) and a run with real users and real data.
This is usually not a problem since, due to frequent changes in
applications, you must work to continuously update the security model
anyway.
eh...this is the real problem for hand made things...but a semi
automatic approach would help.. no?
What about for a learning phase? I mean a semi automatic generation of
rules, based on real clients inputs from the web...
yes it is untrustable...
but there should be some way out there :)
To acquire reliable material for policy generation (and update) is the
most difficult part of the problem. I will be looking at the following
approaches: 1) designate an IP range as trusted, 2) require
administrators to manually review traffic before it is used in policy
generation, and 3) use negative security to assign threat score to
each request using only requests with low scores for policy
generation. A combination of all three is probably the way forward.
By the way , i wrote a mod_html_proxy based hmac signing for links on
the fly named Mod Anti Tamper:
Link: www.wisec.it/projects.php?id=3&lang=en
That's very interesting; it's one of the things missing in ModSecurity.
--
Ivan Ristic
Apache Security (O'Reilly) - http://www.apachesecurity.net
Open source web application firewall - http://www.modsecurity.org
