PC Security - part 2
If you access your email directly from the web choose an email supplier who virus-scans for you (examples are Hotmail and Yahoo), your attachments will then be scanned for viruses by those companies. That doesn’t mean that you don’t need a scanner on your PC, you do. Even though these companies scan for known viruses, you still have the threat from presently unknown ones, and though your own virus scanner also won’t be able to recognise the virus now, it will be able to recognise it later on and be able to eradicate it.
So how do we prevent unknown viruses infecting our PC? Being unknown, our scanner won’t recognise them, so we have to learn the tell-tale signs of infected emails.
The infected email will normally come from someone who has contacted you in the past. So looking at who has sent the email is no help on its own. However, if you look in the subject line, you should ask whether the subject fits the person who sent it. A subject that says “I love you” and that comes out of the blue is a giveaway. Even so, many curious people opened that email and its attachment and got infected with the love bug virus.
When you send emails, make sure that you use the subject line properly. Always put in it something that identifies it as coming from you. I had to ask a colleague whether he sent an email which had as its subject, “this may be of interest”. If he had put, “this Christian web site may be of interest” then I’d have known that it was most likely from him (a Christian) without needing to ask.
So once you are reasonably happy, you open the email. If there is an attachment, look at the last 4 characters of the filename. If they are “.EXE”, “.PIF”, “.SCR”, “.JS” or “.JSE” then don’t open them. Some virus writers give their files names like “APICTURE.GIF.exe” and you might think this was a GIF image file, when in fact it is a “.EXE” file.
The following file types are safe: image formats like JPEG, JPG, GIF, WMF; files that do not contain macros, eg RTF, TXT. I try to only send RTF files. I believe that PDF files are safe even though they contain a macro capability.
Microsoft Word and Excel files (“DOC”, “DOT”, “XLS”, “XLW”) can all contain dangerous macros, and these macros can run as soon as you open the file. Open Microsoft Word and go to Tools:Options and select the security tab and click the macro security button and then select the ‘Medium’ option. This means that whenever a DOC file opens you will have the option to disable any macros. You should always choose to disable macros for documents arriving as mail attachments. Select the same setting for other Office programs like Excel. There are bugs in Microsoft Office that will let certain documents run a macro without you knowing, even if you have macro security switched on. So the first thing to do is go to http://Office.microsoft.com/productupdates and check whether you need to install any security updates. Once the security updates are installed you should be reasonably safe.
If someone sends you an email saying there is a virus that Mcafee or Norton don’t know about and you should do something to your machine, like delete a file, it is very very very likely to be a hoax email. Do NOT pass it on to others. Check it out at http://us.mcafee.com/virusInfo/default.asp?id=hoaxes, then delete it. Do not open any attachments.
Lastly, there are emails that claim to come from the web-site of a well-known company. They either ask you to click on an attachment, or they provide a link to a web-site that looks like the official one. If you have not previously had any contact with the company then just delete the email. If you have contacted them before, you should contact them using that web-site address, NOT via the link in the email. Most sites provide a means to contact them. Use that means to ask whether they have sent this email. DO NOT open any attachment or follow the link till you know it is safe.
And now Part 3
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