Re: Messenger Service security breach

From: Karl Levinson [x y] mvp (levinson_k@excite.com)
Date: 11/06/02


From: "Karl Levinson [x y] mvp" <levinson_k@excite.com>
Date: Wed, 6 Nov 2002 14:07:24 -0500


"Robert Mammel" <mssecurity@e-p-c-s.com> wrote in message
news:843d01c285ac$33877660$2ae2c90a@phx.gbl...
> The attached graphic is an example of a Windows security
> breach, which allows the Windows (2000 and XP in our
> office) system's Messenger Service to display a spam
> message.
>
> Microsoft (see http://support.microsoft.com/default.aspx?
> scid=KB;EN-US;Q330904&) claims the security hole can be
> plugged by disabeling NetBios over TCP/IP. This DOES NOT
> disable the breach. The attached spam was received on
> several computers on our LAN, all of which had disabled
> NetBios over TCP/IP.
>
> We've put off installation of a firewall appliance between
> the router and LAN on the mistaken assumption that we
> could plug the security holes on individual computers.
> This latest security breach has made it obvious that a
> firewall appliance is a necessity and there will be yet
> another box to maintain because of PC operating system
> security bugs.

You could switch to Linux, but you'd still need a firewall. This isn't a
Microsoft-specific problem.

There are free firewalls out there, try one of the linux firewalls mentioned
below, I think you'll find them to rival commercial products for stability,
performance and features, plus you can purchase support if you need it.
Even a Netgear $70 NAT router is probably better than nothing.

================

Which firewall should I choose? Which firewall is the best?

A: The answer to this question varies depending on your computer systems,
your security requirements and your personal preferences. Below are some
firewalls and other forms of firewall-like packet filtering:

NO MATTER WHICH FIREWALL YOU CHOOSE...
No matter which firewall you choose, you should seriously consider
downloading and installing MyNetWatchman or Dshield. These are free
programs that work with your firewall software or hardware to automatically
report hacking attempts to the hacker's ISP. You get to see information
about whether that IP address has been used to scan or hack other computers,
or whether it might be targeting just your computer. You also get to see
whether the ISP has responded or taken action against the offending user.
You can get this software at one of the links below:

www.mynetwatchman.com
www.dshield.org

Also, no matter which firewall you choose, the lists below of port numbers
for common software services may be helpful when configuring your firewall
or when trying to monitor the firewall logs for signs of intrusion:

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q289241 [common
ports on Windows 2000]
http://www.iana.org/assignments/port-numbers
http://www.iisfaq.com/default.asp?View=P106

Additionally, with some inexpensive hardware firewall devices such as
Linksys and Netgear, you may need to use a free syslog client such as
www.kiwisyslog.com in order to capture and preserve the firewall logs onto
your computer. Otherwise, your firewall logs may disappear after a few
minutes, and you may lose your only way of determining who hacked your
computer.

FIREWALL SOFTWARE:
www.sygate.com [free for non-commercial use, also works like a sniffer]
www.kerio.com [free for non-commercial use]
www.agnitum.com [free for non-commercial use]
www.zonealarm.com [free for non-commercial use, also blocks pop-ups]
www.iss.net [Black Ice]
www.symantec.com [Norton]
www.webattack.com
www.download.com
www.tucows.com
[Windows XP users can also consider using the ICF firewall that comes with
XP, more info below]

FIREWALL DEVICES [HOME / SOHO]:
www.linksys.com [starts around $70 US]
www.netgear.com [starts around $70 US]
http://search.ebay.com/search/search.dll?query=firewall [prices on new and
used firewalls]

FIREWALL DEVICES [PROFESSIONAL / ENTERPRISE]:
www.netscreen.com
www.netgear.com
www.intrusion.com
www.cisco.com
www.nortelnetworks.com/products/family/contivity.html
www.nokia.com/securitysolutions
www.microsoft.com/isa
http://search.ebay.com/search/search.dll?query=firewall [prices on new and
used firewalls]

LINUX / BSD FIREWALLS:
http://www.ipcop.org [install to hard drive, friendly GUI]
http://www.smoothwall.org [install to hard drive, friendly GUI]
http://www.devil-linux.org [boot CD firewall]
http://gibraltar.at [boot CD firewall]
http://www.sentryfirewall.com [boot CD firewall]
http://www.thinman.com/eLSD [boot CD firewall]
http://www.closedbsd.org [boot floppy firewall]
http://thewall.sf.net [boot floppy firewall]

INTRUSION DETECTION:
http://www.snort.org [free, has a version for Windows]
http://www.trinux.org [free, runs from a boot floppy disk or CD]
http://www.iss.net

Linux / BSD firewalls can be run on an old spare 486 PC to protect your
network, and the software is often free of charge. Some of the firewalls
above are supposedly intended to be easy enough for small offices and home
users with no previous Linux experience to use. Linux firewalls are one
inexpensive way to be able to add advanced firewall features that may be
very expensive to add to commercial firewalls. [Features such as bandwidth
usage reporting, QoS bandwidth limiting, intrusion detection, alerts in
real-time to your email or pager, a third network interface to create a DMZ,
identical spare backup firewalls for fault tolerance and scalability, etc.
are generally free.] Unlike some commercial firewalls, 24x7 on-site
technical support for Linux / BSD firewalls can be purchased from a number
of companies in most cities.

Intrusion detection is software or hardware that generally monitors the data
transmissions on your network in order to add better alerting, analysis and
detection of intrusions [without necessarily blocking those intrusions].
Note that with most IDS systems, you must tune the default rules and
settings, or else you will receive too many false alarms.

Linux firewalls and intrusion detection are not likely to be the best way to
protect just one home computer or laptop [unless you are an expert computer
user or computer hobbyist]. These tools are probably more useful to network
administrators.

ICF - WINDOWS XP INTERNET CONNECTION FIREWALL -
If you are using a Windows XP computer at home and do not log into a Windows
domain, you can enable the free ICF - Internet Connection Firewall - that
comes with Windows XP. The ICF firewall is generally well respected and
secure for home users.

You can enable or configure ICF either by clicking on Start, Settings,
Control Panel, double-click Networking and Internet Connections, click
Network Connections, right-click the connection on which you would like to
enable ICF, and then click Properties, Advanced and select "Protect my
computer or network."

See the articles below for more information:

How to enable or disable ICF -
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q283673
More information on ICF and how to configure ICF -
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q320855
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q298804
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q308127

=============

How can I harden my computer or server to secure it from hackers?

A: [Note that if you have already been hacked, this section will not help
you re-secure your computer. In this case, you should first read the
section in this FAQ entitled "How can I re-secure my computer or server
after being hacked?"]

Here is the short answer:

1) Do not put the computer onto the network or the Internet until after the
computer has been hardened using the instructions below [or at least not
before a firewall and antivirus have been installed].
2) Use firewall software and hardware and antivirus software that is
configured to download updates every day;
3) Follow the instructions for hardening Windows and IIS at
www.microsoft.com/technet/security ;
4) Install all service packs and security fixes from Microsoft and
otherwise for all Microsoft software on your computer [Windows, IIS, Office,
Internet Explorer, Windows Media Player, etc.] from
www.microsoft.com/technet/security ;
5) [Ongoing] Download MBSA from www.microsoft.com/download and run it now
and also at regular intervals to look for vulnerabilities in your settings,
new patches that are missing, etc. Also, check your antivirus to confirm
that the last successful update was less than 14 days ago.

These steps will make your computer fairly secure, but may still leave some
holes. Keep reading below for additional information you should be aware
of:

A successful hacker, virus or worm intrusion into one of your computers can
drain your free disk space, slow down your Internet connection, compromise
your credit card numbers, damage your personal documents, allow intruders to
access other machines on your network that DO contain important files,
and/or leave you legally liable for other government or business computers
on the Internet that are hacked by an intruder using your computer. This is
why you should consider securing ALL the computer systems in your home or
network, even if you think there is nothing important on the computer or it
is "just a test computer."

All Windows users should seriously consider all of the procedures below to
help prevent intrusions on their computers:

1) Do not put the computer onto the network or the Internet until after the
computer has been hardened using the instructions below. [Un-secured
computers can be hacked in just 15 minutes or less after being put onto the
Internet.] Depending on your environment, it may be acceptable to put your
computer on the Internet after installing a firewall and antivirus software
with the latest updates.

2) Seriously consider enabling or installing firewall software and/or
firewall hardware. There are a number of free firewalls available,
including the ICF feature that comes with Windows XP [unless XP is joined to
a Windows domain], and/or other third-party firewalls available on the
Internet.

For more information on how and where to locate free and not-free firewall
software and hardware, see the section in this FAQ entitled "Which firewall
should I choose? Which firewall is the best?"

3) Seriously consider installing an antivirus program and configure it to
automatically download updates daily.

For more information on where and how to locate and use free and not-free
antivirus software, see the section in this FAQ entitled "Which antivirus
should I choose? Which antivirus is the best?"

4) Follow the instructions for hardening Windows 2000 and also IIS [if IIS
is installed] at www.microsoft.com/technet/security

[Note that for Windows 2000 / NT, hardening IIS should include installing
IISlockdown including URLScan. For computers with FTP service installed, it
should include removing the Posix subsystem and removing write permission
from the anonymous user account, among other things. Information on
removing the Posix subsystem is available at:
www.microsoft.com/technet/security/tools/chklist/CheckList.htm#4
www.labmice.net/articles/securingwin2000.htm]

5) Download and install all the service packs and security patches from
www.microsoft.com/technet/security for all the Microsoft and non-Microsoft
software installed on your computer, especially Microsoft Windows, Office,
Internet Explorer, Outlook Express, Windows Media Player and IIS [if IIS is
installed].

Note that Windows 2000, XP, .NET and NT users should also download patches
for Indexing Services a.k.a. Index Server. Do not assume that Index Server
patches are included with any IIS comprehensive service pack rollup you may
already have installed, because they are not.

[If you want a shortcut to do this faster, you could try this:
* Download and install the latest Windows service pack from
www.microsoft.com/technet/security;
* Reboot and visit http://windowsupdate.microsoft.com to receive additional
patches;
* Reboot, download and run MBSA [Microsoft Baseline Security Analyzer] or
HFNETCHK from www.microsoft.com/download to discover other missing patches;
* Manually download from www.microsoft.com/technet/security and install any
patches that were found to be missing, as well as patches for any server
products that may not be included in Windows Update and MBSA/HFNETCHK, such
as possibly SQL Server, ISA Server, etc.
* NOTE however that Windows Update, MBSA and HFNETCHK do NOT necessarily
list all Microsoft patches or search all Microsoft products, so you could be
missing some patches if you rely just on these tools.]

6) [ONGOING] Re-run the MBSA tool from www.microsoft.com/download every 60
days or sooner to look for missing patches, and confirm that your antivirus
program received an update in the past 10 days or less.

If you want or need even more security [or are particularly paranoid or at
risk], you can consider some of the additional steps below. Some of the
tools below may be more security than you need, unless you are running a
server such as IIS web or FTP services.

* Download and install MyNetWatchman or Dshield. These are free programs
that work with your firewall software or hardware to automatically report
hacking attempts to the hacker's ISP. You get to see information about
whether that IP address has been used to scan or hack other computers, or
whether it might be targeting just your computer. You also get to see
whether the ISP has responded or taken action against the offending user.
This is highly recommended. You can get this software at one of the links
below:

www.mynetwatchman.com
www.dshield.org

* Sign up for the Microsoft security mailing list at
www.microsoft.com/technet/security to receive emails with a link to new
critical security patches as they are released, and install them ASAP.

* Use Vision [or Fport] from www.foundstone.com/knowledge or Active Ports
from www.webattack.com/get/activeports.shtml or pslist / pstools from
www.sysinternals.com to look at the open ports on your computer and the
program or executable using that port. Some firewall software such as
www.sygate.com will also tell you this information.

You can also use the NETSTAT -A command that comes with Windows to look at
open ports; however, this will not identify which program is using the port.

[You may want to run a command such as FPORT >> C:\OPENPORTS.TXT or
PSLIST >> C:\OPENPORTS.TXT or NETSTAT -A >> C:\OPENPORTS.TXT
This command will create a "baseline" text file named c:\openports.txt that
can be compared later with the results of the command to tell you whether
additional ports are now open, a possible sign of intrusion.]

* Consider running one or more vulnerability scanners to look for security
flaws and configuration errors on your computers. Vulnerability scanners
should be run after you have installed and hardened a new computer or
server, and also run at regular intervals to confirm that your computers are
still secure. You might also run a port scanner against your computers as
well to look for open ports.

See the section in this FAQ entitled "How can I scan my computer or firewall
to look for open ports or confirm that my machine is secure?" for more
information.

* Consider searching for and following additional checklists for hardening
Windows 2000 by searching an Internet search engine such as www.google.com
for words such as "harden OR hardening windows-2000" [e.g.
www.google.com/search?q=harden+OR+hardening+windows-2000 ]. Several such
checklists are available at:

http://nsa1.www.conxion.com/win2k/download.htm a.k.a. http://www.nsa.gov
www.labmice.net/articles/securingwin2000.htm
www.labmice.net/security
http://csrc.nist.gov/itsec/guidance_W2Kpro.html
http://csrc.nist.gov/publications/nistpubs/800-44/sp800-44.pdf
http://rr.sans.org

* Uninstall any unnecessary Windows components [e.g. click on Start,
Settings, Control Panel, Add/Remove Programs, Add/Remove Windows
Components]. Pay particular attention to Indexing Service, Internet
Information Services (IIS), Management and Monitoring Tools, Message Queuing
Services, Networking Services, Other Networking File and Print Services,
Outlook Express, and Windows Media Player. If you are not sure whether
something is unnecessary, try searching www.google.com or posting a question
to the appropriate Microsoft security newsgroup.

* Disable any unnecessary Windows services [e.g. click on Start, Settings,
Control Panel, Administrative Tools, Services]. If you are not sure whether
something is unnecessary, try searching www.google.com or posting a question
to the appropriate Microsoft security newsgroup.

* Consider using a Trojan scanner. Antivirus programs generally detect some
but not all of the most common Trojans and hacker tools. Some people choose
to use a Trojan scanner in addition to antivirus.

For more information on where and how to locate and use free and not-free
Trojan scanner software, see the section in this FAQ entitled "Which
antivirus should I choose? Which antivirus is the best?"

* Enable logging. Most logging is disabled by default, and usually this is
not discovered until after an intrusion, when the logs are needed.

Enable logging of your IIS web server, FTP server, etc. For sites with a
small number of hits, consider changing logs to rotate monthly instead of
daily to allow easier searching of logs.

Enable logging on your Internet router, switch or firewall. [Because these
devices usually do not have much storage space for saving logs, doing this
may involve installing free syslog software onto your computer to be able to
capture the logs.]

Enable auditing of security events on your Windows system, including logon
successes and/or failures and NTFS auditing of files and registry keys. For
more information, see the section in this FAQ entitled "How can I enable
auditing / logging on my computer / server?"

Change the Windows event log settings to be appropriate for your
environment. Consider increasing the maximum log size to retain more
information. Be careful not to log too much, or you might find that your
logs contain only a few minutes or hours worth of data.

Check the logs to be sure logs are really being captured.

* Consider using a file change checker, such as the unsupported free tool
Languard File Integrity Checker at www.gfi.com/languard/lantools-fic.htm
Files changing on your system can sometimes indicate a hacker intrusion.

* Consider using a Windows event log monitor. Some types of intrusions
leave entries in one of the logs on your computer. [On an especially
vulnerable or secure system, you should be sure that you've configured
logging to detect events such as intrusions.] Some network monitors such as
www.ipsentry.com can send a message to your email/screen/pager if a server
or service stops responding, an event or error appears in a Windows log,
etc. Windows log monitors can be found by searching an Internet search
engine or your favorite software web site, or by using the links below:

www.ipsentry.com [around $100 US]
www.sunbelt-software.com
www.webattack.com
www.wilders.org
www.download.com
www.tucows.com
www.google.com/search?q=windows+event+log-monitor

* Consider using EFS file encryption [under Windows 2000 / XP / .NET] or
third-party utilities to encrypt the files on your computer may be something
to consider. Some of these utilities can encrypt your entire hard drive
including Windows, whereas other tools just encrypt some of your data files
and are not suitable for encrypting or preventing access to Windows.

Note that using any form of encryption can slow down your computer's
performance. Also, you must be extremely careful to back up and protect
your encryption key and any passwords. If the encryption keys are not
backed up, users can lose their encrypted files forever when Windows is
reinstalled, Windows encounters a problem so that Windows no longer starts
up, etc.

For more information on EFS file encryption on Windows 2000 / XP / .NET, see
the section in this FAQ entitled "I used Windows 2000 / XP EFS file
encryption to encrypt some files. Now, I can't read the files. How can I
unencrypt them or recover the key?"

Third party encryption software can be found at the following locations:

www.pgp.com
www.scramdisk.clara.net
www.e4m.net
www.jetico.com ["BestCrypt"]
www.download.com
www.tucows.com
www.google.com

=================