Personal Computer Security

Network Operations Center -- updated 5/17/2005

Emergency Help: Do you think your PC is infected with a virus or infested with spyware? Login with your Dowling network/email username and password here and get help!

This document is aimed at PC users at home or in the Residences. Recommendations for secure computing on faculty and administrative PCs on campus are at this page.


It doesn't take too much effort to protect your PC from external attack, but like everything else, the more effort you expend, the more results you'll get. You need to start with at least the following:

  1. regular visits to WindowsUpdate
  2. antivirus software
  3. anti-spyware software

For the more diligent, we also list additional measures you can take to protect your PC.

Note: If you have just gotten a new PC, perhaps for the holidays, the very first thing you should do is follow the excellent, detailed instructions at this location: http://www.sans.org/rr/whitepapers/windows/1298.php


Windows Updates

Most people use some version of Microsoft Windows on their PCs. Since Windows is so pervasive, it is targeted more often than other platforms by various forms of malware. Microsoft strives continually to repair problems, and provides updates, mostly free. Visit the Microsoft Windows Update site and follow the instructions there to make your PC automatically update itself whenever a flaw is fixed.

Technical note: some people unknowingly have unlicensed copies of Windows XP. For them, Windows Update will eventually fail, when they try to install one of the major updates. A properly-licensed copy of Windows XP is necessary in order to reliably update your PC at Microsoft's sites.


Antivirus Software

A computer virus by definition attaches itself to legitimate programs, reproduces by infecting other files on your PC, then copies itself to other PCs by way of e-mail, file-sharing programs, chat programs or other methods. Worms, their close cousins, don't attach themselves to another program but exist as separate programs and reproduce in similar ways. Both worms and viruses can cause damage to PCs by deleting files, corrupting data or making your computer inoperable.

Antivirus software protects you by (1) detecting virus and worm files on your hard disk, (2) detecting activity that looks like virus or worm activity, (3) wherever possible, blocking such activity and deleting the offending programs. A good antivirus program acts as a watchdog who wakes up and barks at any sign of intrusion.

Although there are a few free antivirus programs, it's best to buy a commercial antivirus from a well-known company with the resources to "stay on top of" the problem. Some of our favorite antivirus programs are:

It is crucial that you subscribe, for $20-40 per year, to your antivirus vendor's update subscription program. New viruses are detected EVERY DAY, and you MUST update your antivirus program's detection list frequently, even daily.

Be cautious when handling e-mail. NEVER open an attachment you weren't expecting, even if it appears to be from a relative or friend. Most unexpected attachments are viruses. Delete them!

Think you're infected? Two emergency cleanup tools are linked here.

A good antivirus program and update subscription is step one, but it's not enough...


Anti-spyware software

As the web has evolved into a commercial marketplace, advertising has become a big business. It has become very profitable to find ways to target ads instead of sending them out at random. Your browser may even be "hijacked" to always go to one set of vendors web sites when you try to go anywhere else. Targeting and redirecting of this sort is usually done by installing "spyware" on your PC.

How did this software get installed? There are many ways. Usually, you have downloaded a program offered to you for "free". When you install it, there is a legal notice that you must OK - most people ignore them, but somewhere in the notice you are giving your permission to install additional software besides the "free" program. There are many other ways that spyware can be installed, but this is the most common.

There are at least 15,000 such programs identified by anti-spyware software. If you do enough web-surfing, your PC may have several hundred tracking programs installed! Eventually, your PC is spending so much time reporting your behavior that it scarcely has time to allow you to engage in it. Your PC slows to an unusable crawl.

The solution to this nightmare is to install anti-spyware software. The anti-spyware industry is not as mature as the anti-virus industry, so you may need to read more in order to understand what's going on.

Our favorite anti-spyware programs include:

We recommend you obtain one or more of them, and learn how to use them. They can be used both to cleanse your PC of spyware, and to prevent further installations.

We're also very fond of SpywareBlaster and SpywareGuard, which do their best to prevent installation of spyware - an ounce of prevention, so to speak. And they're both free.

Microsoft has posted information about spyware at http://www.microsoft.com/athome/security/spyware/default.mspx.


Additional Measures, More Information...

There are a few other things you can do to prevent viruses, worms, popups and tracking software from infiltrating your PC:

  • Secure your PC right from the start. Follow the instructions at http://www.sans.org/rr/papers/index.php?id=1298 to lock it down BEFORE you connect it to any network. Don't become a statistic!
  • Run ANY browser except Internet Explorer. The majority of spyware operates most effectively on the browser most people use. Be different! Try Mozilla (free), FireFox (free), Netscape (freeware and commercial versions available) or Opera (free and commercial versions available).
  • If you must run Internet Explorer, goto this page and read about Enough is Enough. This is a freeware program that gives you much greater control of the security features of IE.
  • If you must run Internet Explorer, goto this page and download ScriptSentry. This is a freeware program that can help you control scripts that run in Internet Explorer. Many such scripts are benign, but some are malicious - and you'd like to know if one is trying to install something, right?
  • Read carefully any licensing agreements displayed when you install software. If it includes language about tracking your behavior, abort the install and find another program. KaZaA? NO! (see Section 9). ShareAza? Yes! (No spyware - GPL license.)
  • Run a program like WinPatrol or SpywareGuard to alert you to programs trying to install themselves. SpyBot Search and Destroy also contains an "immunize" function that does the same thing.
  • Run a program like SpywareBlaster, or install the "inoculate" feature of your anti-tracking software, to add another layer of protection against unwanted software installs.
  • Install a personal firewall on your PC. Discussion is here, and some of our favorites include: Note that if you use Windows XP, and you update your PC with Service Pack 2, it contains a personal firewall that's turned on by default. Although most authorities prefer ZoneAlarm, it's better than no firewall at all.
  • NEVER, EVER open an e-mail attachment unless you are expecting it - even if it looks like it came from a friend or relative. Unrequested attachments are usually viruses! Consider any attachment to be the electronic equivalent to a mail-bomb, and act accordingly. We're repeating this warning here because it's important.
  • "No legitimate organization on the planet will EVER send you an update file attached to an email message."
    -- Patrick Douglas Crispen, http://www.netsquirrel.com/

Securing your PC and making the Internet a useful resource requires some work and study. Below are some resources to help you take your skills further. If you find others and would like to share them with other Dowling students, please e-mail them to the Network Operations Center.




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