How To Avoid Viruses
For more on computer viruses and free anti-virus software for faculty, staff and students visit BU’s IS&T page
1: Install quality antivirus
Many computer users believe free antivirus applications, such as those included with an Internet service provider’s bundled service offering, are sufficient to protect a computer from virus or spyware infection. However, such free anti-malware programs typically don’t provide adequate protection from the ever-growing list of threats.
Instead, all Windows users should install professional, business-grade antivirus software on their PCs. Pro-grade antivirus programs update more frequently throughout the day (thereby providing timely protection against fast-emerging vulnerabilities), protect against a wider range of threats (such as rootkits), and enable additional protective features (such as custom scans).
2: Install real-time anti-spyware protection
Many computer users mistakenly believe that a single antivirus program with integrated spyware protection provides sufficient safeguards from adware and spyware. Others think free anti-spyware applications, combined with an antivirus utility, deliver capable protection from the skyrocketing number of spyware threats.
Unfortunately, that’s just not the case. Most free anti-spyware programs do not provide real-time, or active, protection from adware, Trojan, and other spyware infections. While many free programs can detect spyware threats once they’ve infected a system, typically professional (or fully paid and licensed) anti-spyware programs are required to prevent infections and fully remove those infections already present.
3: Keep anti-malware applications current
Antivirus and anti-spyware programs require regular signature and database updates. Without these critical updates, anti-malware programs are unable to protect PCs from the latest threats.
In early 2009, antivirus provider AVG released statistics revealing that a lot of serious computer threats are secretive and fast-moving. Many of these infections are short-lived, but they’re estimated to infect as many as 100,000 to 300,000 new Web sites a day.
Computer users must keep their antivirus and anti-spyware applications up to date. All Windows users must take measures to prevent license expiration, thereby ensuring that their anti-malware programs stay current and continue providing protection against the most recent threats. Those threats now spread with alarming speed, thanks to the popularity of such social media sites as Twitter, Facebook, and My Space.
4: Perform daily scans
Occasionally, virus and spyware threats escape a system’s active protective engines and infect a system. The sheer number and volume of potential and new threats make it inevitable that particularly inventive infections will outsmart security software. In other cases, users may inadvertently instruct anti-malware software to allow a virus or spyware program to run.
Regardless of the infection source, enabling complete, daily scans of a system’s entire hard drive adds another layer of protection. These daily scans can be invaluable in detecting, isolating, and removing infections that initially escape security software’s attention.
5: Disable autorun
Many viruses work by attaching themselves to a drive and automatically installing themselves on any other media connected to the system. As a result, connecting any network drives, external hard disks, or even thumb drives to a system can result in the automatic propagation of such threats.
Computer users can disable the Windows autorun feature by following Microsoft’s recommendations, which differ by operating system. Microsoft Knowledge Base articles 967715and 967940 are frequently referenced for this purpose.
6: Disable image previews in Outlook
Simply receiving an infected Outlook e-mail message, one in which graphics code is used to enable the virus’ execution, can result in a virus infection. Prevent against automatic infection by disabling image previews in Outlook.
By default, newer versions of Microsoft Outlook do not automatically display images. But if you or another user has changed the default security settings, you can switch them back (using Outlook 2007) by going to Tools | Trust Center, highlighting the Automatic Download option, and selecting Don’t Download Pictures Automatically In HTML E-Mail Messages Or RSS.
7: Don’t click on email links or attachments
It’s a mantra most every Windows user has heard repeatedly: Don’t click on email links or attachments. Yet users frequently fail to heed the warning.
Whether distracted, trustful of friends or colleagues they know, or simply fooled by a crafty email message, many users forget to be wary of links and attachments included within email messages, regardless of the source. Simply clicking on an email link or attachment can, within minutes, corrupt Windows, infect other machines, and destroy critical data.
Users should never click on email attachments without at least first scanning them for viruses using a business-class anti-malware application. As for clicking on links, users should access Web sites by opening a browser and manually navigating to the sites in question.
8: Surf smart
Many business-class anti-malware applications include browser plug-ins that help protect against drive-by infections, phishing attacks (in which pages purport to serve one function when in fact they try to steal personal, financial, or other sensitive information), and similar exploits. Still others provide “link protection,” in which Web links are checked against databases of known-bad pages.
Whenever possible, these preventive features should be deployed and enabled. Unless the plug-ins interfere with normal Web browsing, users should leave them enabled. The same is true for automatic pop-up blockers, such as are included in Internet Explorer 8, Google’s toolbar, and other popular browser toolbars.
Regardless, users should never enter user account, personal, financial, or other sensitive information on any Web page at which they haven’t manually arrived. They should instead open a Web browser, enter the address of the page they need to reach, and enter their information that way, instead of clicking on a hyperlink and assuming the link has directed them to the proper URL. Hyperlinks contained within an e-mail message often redirect users to fraudulent, fake, or unauthorized Web sites. By entering Web addresses manually, users can help ensure that they arrive at the actual page they intend.
But even manual entry isn’t foolproof. Hence the justification for step 10: Deploy DNS protection. More on that in a moment.
9: Use a hardware-based firewall
Technology professionals and others argue the benefits of software- versus hardware-based firewalls. Often, users encounter trouble trying to share printers, access network resources, and perform other tasks when deploying third-party software-based firewalls. As a result, I’ve seen many cases where firewalls have simply been disabled altogether.
But a reliable firewall is indispensable, as it protects computers from a wide variety of exploits, malicious network traffic, viruses, worms, and other vulnerabilities. Unfortunately, by itself, the software-based firewall included with Windows isn’t sufficient to protect systems from the myriad robotic attacks affecting all Internet-connected systems. For this reason, all PCs connected to the Internet should be secured behind a capable hardware-based firewall.
10: Deploy DNS protection
Internet access introduces a wide variety of security risks. Among the most disconcerting may be drive-by infections, in which users only need to visit a compromised Web page to infect their own PCs (and potentially begin infecting those of customers, colleagues, and other staff).
Another worry is Web sites that distribute infected programs, applications, and Trojan files. Still another threat exists in the form of poisoned DNS attacks, whereby a compromised DNS server directs you to an unauthorized Web server. These compromised DNS servers are typically your ISP’s systems, which usually translate friendly URLs such as yahoo.com to numeric IP addresses like 126.96.36.199.
Users can protect themselves from all these threats by changing the way their computers process DNS services. While a computer professional may be required to implement the switch, OpenDNS offers free DNS services to protect users against common phishing, spyware, and other Web-based hazards.