Security Basics mailing list archives

Re: web browsing in production environment - a journey through comfort and security


From: Robin Wood <dninja () gmail com>
Date: Mon, 6 Jul 2009 16:15:52 +0100

2009/7/6  <info () hitcon de>:



today we have a environment which is arranged as follows:

- a windows 2003 domain
- a citrix terminal server farm ( 6 servers, 120 employees )
- a astaro firewall appliance ( with web security - it uses its own proxy
service (astaro engineered) and anti virus modules - clam & avira )
- a squid proxy server (3.x) (it does authentication against domino ldap)
with trend micro web security suite and squidguard for some url filtering
(mainly pron) - the blacklists are updated once a day

* web browsing is only possible via the citrix sessions of the users ( no
local access from desktop or from somewhere else). unfortunately we need to
use internet explorer (7) because most of the sites, which users reach work
only with IE :-(
( i already tried to migrate firefox without success )

* we limit the active content of websites via microsoft group policies.
only websites which are registered as trusted sites in group policies can
show its active content ( java, active x, javascript etc)

* we have a chain of proxy servers. (see list of environment).

so if a user start its internet explorer in it's citrix session, the IE
passes its way through the proxy servers:

1. checks if the website is a trusted site in group policy or not and
starts active content or not

2. squid proxy server (located in demilitarised zone) -> authentication
against LDAP (and logs all requests with username, ip, etc.)

3. Checks SquidGuard if website is on  blacklist

4. passes traffic to trend micro web security suite ( anti virus engine for
http(s) and ftp )

5. passes the traffic to the astaro (which is the parent proxy) which uses
its own scanners (clam and avira)


I don't know an answer to your question but I would suggest that
putting out this much information about your corporate network is not
a good idea.

Robin

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