PC support #4: Viruses, Worms and Trojans, part 3 29th October 2001 C O N T E N T S ----- USING ANTI-VIRUS SOFTWARE 1. How do I use my anti-virus software to check my PC for viruses? 2. When should I do a manual scan? 3. How do I do a manual scan of a whole disk? 4. What do I do if I find a virus? 5. How do I do a manual scan of individual files or folders? ----- CONTACT DETAILS ------------------------------------------------------------------------ ----- USING ANTI-VIRUS SOFTWARE ---------------------------------------- ------------------------------------------------------------------------ -- 1. How do I use my anti-virus software to check my PC for viruses? When it is set up correctly, the automatic part of an anti-virus package (called the "on access" or "real-time" scanner) will check files as you use them to make sure that you have no viruses. E-mail is checked as it is received, programs are checked as they are run, and files are checked as they are downloaded from the Internet. However, "on access" scanning is not perfect, and it is possible for a virus to occasionally slip past it and lurk on your hard disk. Hence you should learn how to do manual or "on demand" scans. You can scan individual files and folders, or whole disks (e.g. your hard disk, a CD or a floppy disk). -- 2. When should I do a manual scan? There are no fixed rules on this. Some anti-virus software will warn you if it thinks it's too long since you last scanned your complete system, but really it's up to you. I would recommend a complete scan of your hard disk every 4-6 weeks for reasonably frequent PC users. You should also consider doing manual scans of any files you are not sure of. For example, if someone gives you some files on a floppy disk or CD, you would be well advised to check them in case that person (perhaps unknowingly) has a virus. I usually do manual scans of any files I download from the Internet, as my software is set up to do a more thorough scan when I do it manually, and it's an extra level of confidence. -- 3. How do I do a manual scan of a whole disk? This depends on which anti-virus package you use, and some packages allow you to use more than one method. Here are outline methods for the three we covered in the last support note. (a) McAfee VirusScan 5 Start McAfee VirusScan Central. There may be an icon for this on the desktop - if not, you should find it on the start menu, probably under: Programs -> McAfee Office -> McAfee VirusScan When it starts, click the "Scan" button. The main view will change to show "My Computer", followed by a list of drives. To do a complete scan of your system (i.e. the whole hard disk plus any other disks) click on "My Computer" and then click the "Scan Now" button. Alternatively, to scan a particular disk (e.g. a floppy disk or a CD) look for that disk in the list and click it. Then click the "Scan Now" button. The scan will now start. (b) Norton AntiVirus 2001 Start Norton AntiVirus. You can use an icon on the desktop if there is one, or you will find it on the start menu - probably at: Programs -> Norton AntiVirus -> Norton AntiVirus 2001 The main Norton AntiVirus status screen should now appear. ( Take a moment to check what you see on the main status screen. If there are red crosses against any items, Norton thinks there's a problem with that item - e.g. you've left it too long since downloading new virus definitions, or the "Real-time" (automatic or on access) scanner isn't running. Double click the item and Norton will prompt you what to do. ) Several options are listed down the left hand side of the Norton AntiVirus window. One of these is "Scan for Viruses" - click it. A list of possible items to scan will now appear. To do a complete scan of your system (i.e. the whole hard disk plus any other disks) click on "My Computer" and then click the "Run Scan Now" button. Alternatively, to scan a particular disk or disks, click on the appropriate item, then click "Run Scan Now". If you chose "Scan Drives" Norton will prompt you to choose which drives you want to scan when it starts. The scan will now start. (c) Trend PC-cillin 2000 Start PC-Cillin. You can use an icon on the taskbar or desktop if you have one, or you can find it on the start menu - probably under: Programs -> Trend PC-cillin 2000 -> Trend PC-cillin 2000 When the main PC-cillin window appears, the "Scan Wizard" page should be visible. If not, click on the "Scan" button on the left, then click "Scan Wizard". Choose what you want to scan from the list - choose "Drives/directories" if you are going to scan your whole hard disk. Then click "Next". On the next page you can choose how you want the scan to be done. If you don't understand the options, click the "Default" button and they will automatically be set to the default settings. Now click "Next". A list of all your disks will appear, with "My Computer" at the top. To scan the whole PC, click the box by "My Computer" to put a tick in it (ticks will also appear against all the disks). Now click the large "Scan" button, and the scan will start. The scan may take some time (possibly half an hour or more), and the PC may be rather sluggish whilst it's doing it, so it's best to leave it going whilst you go and do something else! At the end, it will tell you if it has found any viruses. -- 4. What do I do if I find a virus? The precise way in which viruses are dealt with depends on the anti-viruses package you are using, but most of them offer you the following basic choices: * Clean the infected file. Some viruses attach themselves to good files. Cleaning removes the virus but keeps the file. It may not always be possible to clean a virus (the program will warn you). * Quarantine the virus. This does not delete the virus, but keeps it in a safe place. Someone can then try to recover the data from it at a later date. Only useful if you think that the infected file is important and it can't be cleaned by the anti-virus program. * Delete the infected file altogether. * Ignore the virus - DON'T CHOOSE THIS ONE!!! Here's how to deal with a virus if a system scan finds one: (a) McAfee VirusScan 5 When the system scan finishes, the lower part of the main window will list any infected files found. Click on a file, then click the appropriate button below (Clean, Delete, or Quarantine). Clean will be faint if it's not possible to clean the virus. (b) Norton AntiVirus 2001 If Norton AntiVirus finds any viruses, a window will appear listing the viruses. You will have the options of "Automatic" or "Manual" cleaning - if in doubt choose "Automatic". Click "Next" and Norton AntiVirus will "talk you through" the process of cleaning or deleting the virus. (c) Trend PC-cillin 2000 If you have chosen the default settings when you started the scan, (see item 3 above), PC-cillin will automatically clean or quarantine the virus for you. You don't need to do anything else. -- 5. How do I do a manual scan of individual files or folders? The method is similar for all three of the programs we have covered here, and most other anti-virus programs will be similar. Click on the file or folder you want to scan using the right mouse button (unless you have the buttons reversed for left handed operation). A menu will appear. Look for a scan or anti-virus option on the menu, e.g.: * "Scan for Viruses" (McAfee) * "Scan with Norton AntiVirus" (Norton) * "PC-cillin" (Trend PC-cillin) If you can't see an option like that, your package does not offer the option of individually scanning that item. If you can see such an item, click it and the file or folder will be scanned. The method of dealing with a virus if one is found is more or less the same as in item 4 above. ------------------------------------------------------------------------ ----- CONTACT DETAILS ------------------------------------------------- ------------------------------------------------------------------------ Andrew Bovett e-mail: mailto:pcsupport@abovett.co.uk web site: http://www.abovett.co.uk