Safe Computing
Email Attachments and Viruses
One of the most common means by which computer viruses and worms spread is through email attachments. When opened, these attachments can give hackers complete control of your machine, or intiate an attack on another machine, or start sending out copies of itself to email addresses it finds on your hard drive - or all of the above. Malevolent software of this type has crippled personal machines, email servers, and networks at the University and everywhere on the Internet multiple times - and will again.
For more information about the potential dangers of email scams and bad attachments, you can read Security Cartoon, a web comic written to inform computer users of the possible risks of using the Internet.
This page provides a list of simple guidelines which, if followed, will dramatically reduce the chances that you will be infected with a virus sent through an email attachment.
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INSTALL ANTIVIRUS SOFTWARE AND KEEP IT UP TO DATE.
You should install antivirus software and keep its virus definitions current (most antivirus programs can be configured do this automatically). NSIT provides McAfee VirusScan Enterprise and Virex antivirus software to members of the University community.
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DON'T OPEN UNEXPECTED ATTACHMENTS.
No kidding -- if you don't open an attachment, it can't infect you (unless it's found a security hole in your email client). Many people fall into the habit of opening attachments without thinking about it. Don't do this; you should always think about whether you want to open the attachment first. Assume an attachment is hostile until proven otherwise.
Practically speaking, of course, sometimes you are in a position in which you have to open attachments. In that case, you should only open it if it passes through all the other guidelines, as well.
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DON'T OPEN ATTACHMENTS FROM STRANGERS.
Ever. If you aren't absolutely certain you know the person who sent you the attachment, don't open it.
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DON'T OPEN UNEXPECTED ATTACHMENTS.
If you do know the person in question, but weren't expecting them to send you an attachment, contact them and confirm that they sent it before you open it.
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DON'T OPEN UNUSUAL ATTACHMENTS.
Most of the attachments you receive probably fall into a few recognizable categories -- Word documents, Excel spreadsheets, PowerPoint presentations, and/or Acrobat PDFs, for example. Learn to recognize the icons and filename extensions associated with these files; if you receive an attachment that has an unusual icon, or an unusual extension (especially ones like .pif, .scr, or .exe), don't open it.
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DON'T OPEN ATTACHMENTS FROM STRANGE-LOOKING MESSAGES.
If you receive several unexpected messages from different people with identical subject lines, it could be a virus or worm. If the subject line or message body before the attachment seems unusually vague, incoherent, or incomplete, don't open the attachment. If it just looks "wrong", don't open the attachment.
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DON'T CHECK YOUR EMAIL WITH MICROSOFT OUTLOOK OR OUTLOOK EXPRESS
Although all email clients are vulnerable to some viruses, Outlook and Outlook Express are the email clients most often targeted and easiest to exploit. Outlook and Outlook Express use Internet Explorer's rendering engine to format messages for display meaning it incorporates the vast majority of IE's vulnerabilities in addition to its own, creating the worst of both worlds.
For a more secure stand-alone email client, we recommend Thunderbird, which can be downloaded for free with the University Connectivity Pack.
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KEEP YOUR OPERATING SYSTEM PATCHED
Most operating systems are equipped with some mechanism for updating the security vulnerabilities that many viruses exploit. See the bottom of this email for more information on patching your operating system.
For instructions on keeping your operating system patched, stop by our Windows Update or Mac Software Updates support pages.
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IF IN DOUBT, CALL 4-TECH.
If you receive a message with an attachment and are unsure of its contents, call the NSIT Support Line at 834-8324 and they can determine if it is a worm.
NSIT licensed antivirus software can be downloaded from: http://antivirus.uchicago.edu
Last updated: 7/3/08