[unisog] Developing "Security Guidelines" email

Nguyen, Minh Nguyen at lsdo.ucdavis.edu
Fri Feb 25 22:09:46 GMT 2005


Josh,

1.  You might want to make a note that when setting up a machine, it
should be done behind a firewall (DSL Router box).  Only after all
patches have been applied and security setting have been applied,  is it
"safe" to directly connect to the internet.

2.  Make sure that unnecessary services are disabled or not installed.

Minh 

____________________________________________
Minh Nguyen
Assistant Dean of Technology
College of Letters & Science Deans' Office
mailto:mtnguyen at ucdavis.edu (530)752-7647


-----Original Message-----
From: unisog-bounces at lists.sans.org
[mailto:unisog-bounces at lists.sans.org] On Behalf Of Joshua Beeman
Sent: Friday, February 25, 2005 12:15 PM
To: unisog at lists.sans.org
Subject: [unisog] Developing "Security Guidelines" email

On occasion we have receive an email from an IT group on campus that
says:

"Help!  We have a machine that we've wiped & built from scratch 3 times,
and it keeps getting hacked.  What should we do?"

The problem from our perspective in issuing general guidelines to this
type of request is that every school or center tends to be set up
slightly different from the next.  That said however, we still hope to
be able to provide a list of things to consider that will be helpful,
stimulate new thought, etc.

Towards this end we came up with the list below.  Many of the items are 
biased towards the MS Windows OS.   If you maintain a similar list
and/or 
have any feedback or comments, they would be greatly appreciated.

Thanks very much,

joshb

********************

1. P2P - If possible, remove any installed P2P software.  Emphasizing to
the user that this is a common vector for spyware and unintended
disclosure of information hopefully makes them think twice before
reinstalling it right after you leave.

2. Strong Passwords / Common passwords - Make the user change their
password and enforce strong passwords.  If the user is using the same
username/password combination they were the first time the machine was
compromised, or if the user has a weak password, it may not matter
whether the box was effectively rebuilt or patched.  Additionally,
consider if you are using the same username/password combination (e.g. -
local administrator password, generic accounts) on multiple machines.  A
compromise on one machine may effect the integrity of multiple machines
in your domain or on your network.  Another reason to enforce strong
passwords, or longer passphrases, and change them periodically.

3. Software firewall - Enable the integrated firewall or install a
software firewall to block incoming connections.  If it is a server, or
simply a critical host, consider a hardware firewall of the appropriate
scale.

4. Anti-Virus - Make sure that the latest version of the anti-virus
client is installed and that the definitions are up to date.  If you are
not already, consider running a managed solution that allows you to push
AV definitions and upgrades from a central location
(http://www.upenn.edu/computing/virus/manage-sw.html).

5. OS Patches/SUS service - Make sure that the operating system is up to
date at all times.  If you are not already, consider running a SUS or
SMS server, or participating in the University's SUS program 
(http://www.upenn.edu/computing/sus/).   Additionally, for Windows 
machines, consider using the Microsoft Baseline Security Analyzer to
identify vulnerabilities in the OS as well as certain applications
(http://www.microsoft.com/technet/security/tools/mbsahome.mspx).

6. IPSEC filtering - Consider deploying Microsoft's IPSEC as a Group
Policy on your domain, or at the very least, on individual hosts.  IPSEC
has two
functions:
         a) to protect the contents of IP packets (data integrity) and
         b) to provide a defense against network attacks through packet
filtering and the enforcement of trusted communication (availability)

With IPSEC filtering in place, you can restrict incoming & outgoing
traffic with a granularity not typically associated with integrated
software firewalls.  You can significantly limit, in real-time, the
potential for internal & external (Penn & non-Penn source) exploits with
custom rule-sets that are specific to your environment, to a particular
host, or even to a particular exploit that happens to be circulating.

A quick search of the Microsoft website will turn up a number of
documents relating to this topic.  I this is one of the clearer MS IPSEC
overviews (sorry for the long URL):
http://www.microsoft.com/windowsxp/home/using/productdoc/en/default.asp?
url=/windowsxp/home/using/productdoc/en/sag_IPSECconcept.asp

7. Create & Apply security templates -  Using the Microsoft Management
Console with the "Security Configuration and Analysis" and the "Security
Templates" snap-ins, you can load default policy templates with varying
degrees of strictness, such as "SECUREWS" (secure workstation) and
"HISECUREWS" (highly secure workstation), and then compare your current
configuration to these templates.  After reviewing the differences, you
can save your own template based on the default recommendations and your
organizations needs and apply this template to computers that you
support individually or through a Group Policy.  Here is some sample
documentation from MS:
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs
/en-us/sag_scedefaultpols.mspx

9. Imaging - If you are using disk imaging (e.g. - Ghost) to repair
infected machines and you see compromises quickly *after* re-imaging a
host, you may need to consider checking the base image for
vulnerabilities 
such as the ones listed above and possibly rebuild it.   If you are
unsure 
about the image and want to set up a test host for Security to do a
full-blown vulnerability scan, just contact our office at 
security at isc.upenn.edu.   Make sure if you request this that it is a
test 
or unused system, as a full-scan of this nature can be destructive.

10. Restrict end-user privileges - If you are not already doing it, you
may wish to restrict standard end-users with policies and profiles from
having the ability to install applications or modify the PC
configuration in any way.  Obviously, this may not work for all
environments.



--
Joshua Beeman
Sr. Information Security Specialist
University of Pennsylvania
jbeeman at isc.upenn.edu
(215) 573-6798
http://www.upenn.edu/computing/security

What is the single most valuable piece of data on your computer?  Is it
backed up? 


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