There are many viruses and worms out there that could infect your computer. Some are harmless, but, they do have the capacity to do any number of nasty things, up to and including, erasing all data from your computer. Here's how to keep those nasty critters off your PC!
1. Email is the most common way of getting infected. While you can safely open any mail, NEVER NEVER NEVER click on a link in email that you are not positive is from a trusted source! Here are two common scenarios:
* You get an email from someone you DON'T know. You open it. It tells you (or, persuades you) to click on a link in the email. You do so. Bingo, that is when you get infected. Frequently, the email appears to be from your bank, a company you know, etc. Don't fall for it! It was actually malicious code executed in your browser that allowed it to look like it is coming from an actual business. A good way to avoid this is to use Mozilla Firefox, for the have are known to be more secure. Businesses (almost) never send unsolicited email.
* You get (what appears to be) an email from someone you DO know. But, unknown to you, a virus or worm generated that email (and not your friend). It could be, your friend's PC is infected, but, not always. Obviously, the actual email writer doesn't know you and cannot say anything personal to you, so, typically, it says something like "Click on this link for some important information..." etc. Bingo! Infected!
2. Don't click on pop-up windows that announce a sudden disaster in your city! A cracker (Crackers hack people with evil intent, hackers don't do things to damage your property, or steal data on it in any way. To confuse the terms will make many angry). has used your IP (Internet Protocol) address to determine your location. He then display a headline that you will be very tempted to click on, in order to learn more about "the tornado that just struck your city" (or similar). You click...bingo...infected!
3. Be careful about using MS Outlook. Outlook is more susceptible to worms than other e-mail programs, unless you have efficient Anti-Virus programs running. Use Pegasus or Thunderbird (by Mozilla), or a web-based program such as Hotmail or Yahoo (In Firefox).
4. Install an Anti-Virus program(ex. Norton, F-Secure, Sophos or McAfee.) Also available is the free AntiVir virus scanner. Make sure you keep your virus definitions updated and run a full system scan weekly.
5. Install an Anti-Spyware program(ex. Ad Aware SE, Windows Defender), that operates against internet malware and spyware. Just like Anti-Virus, keep it updated, and do a full system scan weekly.
6. If someone sends you an attachment in e-mail or instant messaging, do not open it. If it is a picture, text or sound file (these attachments end in the extensions .txt, .jpeg, .gif, .bmp, .tif, .mp3, .htm, .html, and .avi), you are probably safe, but still do a scan before opening. Many crackers know that people trust documents like those and the go out of there way to make you regret opening them. High risk file extensions include .exe, .bat, and .vbs, for their main purposes are to execute code, so the file openly admits that something will happen. You can negate the risk by preforming scans with your antimalware AND antivirus. If someone you know very well sends you a Word attachment or other type of file, e-mail them to ask them if they meant to send it to you. If they say yes, you can open it, but you might still be at risk if they are not good about running Anti-Virus scans or careful about what they download. Be wary of attachments with a double extension, such as .txt.vb or .jpg.exe, as the system will only recognize the extension to the extreme right, and run the file as such. Double extensions exploit an option in Windows to hide known file extensions thus hiding the second dangerous extension and showing only the first safe extension. Ensure that this options is disabled to more easily identify these files. Double extensions are often a good indicator that the file is malicious.
7. Do not use disks that other people gave you, even from work. The disk could be infected with a virus. Of course, you can run a virus scan on it first to check it out, but AV programs are not 100% effective. If the disk (especially if its a hard disk) can be wiped using a bootable CD like DBAN (Google DBAN and you will see the page) and then the drive will be completely safe. Disable any autorun options so that you can scan contents of the disk before executing them.
8. Do not download software from just any old website. If it is a reputable site that you trust, you are probably safe. The threat is not only from software; don't download Word documents or other non-HTML files that have something other than one of the extensions listed above, either.
9. Set up your Windows Update to automatically download patches and upgrades. This will allow your computer to automatically download any updates to both the operating system (I.E Windows) and Internet Explorer. These updates fix security holes in both pieces of software.
10. Consider switching to a different web browser. Other web browsers (such as Firefox or Opera) are considered to have better security than Internet Explorer; some people also see them as more flexible and extensible browsers.
11. Be careful when surfing. You can get a malicious script from a webpage and not know it. If you have your IE set up for the maximum security settings, you are probably safe. You can try disabling javascript, but it may also break benign functionality on reputable websites. If you ever get a window asking if you want to allow an automatic install, say "No" unless you know the site requesting the install. Also, don't go to any porn sites. Those are almost always viruses.
12. Read about the latest virus threats so you are aware of the potential danger. Go to Symantec's page to read about them daily.
13. Try to balance paranoia with common sense. Some people get really weird about viruses, spyware, etc. It's just a computer! Back up your data and follow these steps, and it shouldn't be a big problem. Some people would suggest that you make sure you have a firewall and run anti-spyware programs as well. I'm not sure either of those will protect you from viruses, but they will protect you from cracking and from spyware. Microsoft's Antispyware and Ad-Aware are the best anti-spyware/virus programs I have found. Good luck!
14. Use a software firewall! Even if you have a hardware firewall, always use a software firewall (ex. Norton, Mcafee, there's also free ones- ZoneLabs ZoneAlarm).
15. Scan things you download! Be a total nut with this. Scanning new files is cheap, fast, and easy. Even if the file came from a trusted source, their computer might have been compromised without their knowledge. Anything you get from P2P software you should scan, as you are getting it from a stranger.
16. Stay away from file-sharing sites. Sites that distribute illegal versions of software (sometimes referred to as cracks), music, or "free movies" are known to be riddled with virii and trojans. This include torrents or other forms of P2P activities. Staying away from these sites is in your computer's health's best interest, as well as a good way to avoid being sued for copyright violation.
* If you do choose to partake in these illegal activities, check the filesize before downloading. Movies shouldn't be .EXEs or 24K.
17. View the files in a Sandbox
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