Protecting against viruses when using Outlook Express

These are simple techniques but they work! However, be aware that even though these techniques work - the author cannot be held responsible for any damage viruses or worms may cause.

Basically, viruses and worms themselves are nothing fearful or nothing to panic about. They are usually small computer programs. However when run they may do all kind of things – from those that are completely benign to those that slow down computer systems, Internet connections and finally those that destroy data.

Usual ways to get them may be using email attachments, security holes in operating system or running potentially unsafe software.

However, e-mail attachments are very common way to get them so here are some rules you should follow when receiving such files.

Common filenames and sizes of viruses

If you get a file that is sized approximately 10-50 Kb (this is not a general rule but usual usual size of e-mail viruses) and with weird name – and by weird I mean something you didn’t really expect like “surprise.scr” or “gift4you.exe” put yourself on HIGH alert. These are most probably viruses. Note that these filenames come in different flavour, shape and colour. These are only general examples. Especially be careful with exe files.

Common file extensions

File extension are last 3 or 4 letters behind the dot sign. Here are some examples for common executable filename extensions (executables meaning – they can execute code but also can hold viruses): .EXE, .BAT, .COM, .SHS, .VBS, .SCR, .PIF and sometimes .JSE and .VBE. These all can be executed on Windows. You should take extra precaution when you want to execute these. They are dangerous only if they contain malicious code of course.

There are also safe extensions – you cannot get virus from data file like for example TXT, AVI or GIF or JPG. However, there are few tweaks to these as well. There are viruses that try to masquerade themselves as a “safe” extension for example readme.txt.scr – now note that you should always take a look at last 3 letters. No matter how safe it looks. Sometimes it can be also further hidden – consider this name as well

“readme.txt                  .scr”
(without quotes)

In this example virus author wanted to make it look like TXT document, included A LOT of spaces in filename that are not visible in Outlook Express – as it displays only a portion until the end of the screen. So you may think it is a real readme.txt file. This one even had an ICON like notepad icon to make it look even more like TXT document.

Now note, none of the e-mail clients may be safe to this trick but if you save this attachment and take a look at last 3 letters you WILL see SCR which is unsafe extension. Take into account file size and these lot of spaces and common sense tells you that it is a virus and you should not run it.

However you may also remember general rule – DO NOT RUN ANYTHING that is unsafe or you don’t know why / where from it came to you.