Every now and again something comes along which really tries everyone to the limit. Last week was just one of those times.

C rang in a blind panic saying her computer had slowed right down and windows were popping up like Blackpool lights. What’s more the Internet connection was so slow that it was virtually unusable and AVG (the anti virus program) kept flashing up warnings of impending doom.

Everything that was happening was a classic example of a fairly serious infection of nasties. As it happened there were a number of [1] Trojans which had got in despite an up-to-date anti virus program and a reasonable firewall.

The question is how?

The answer should be a salutary example to us all.

After lots of effort involving about half a dozen different malware (MALious softWARE) “scrubbers” it looked like all the trouble came from C installing an apparently useful program called “Antivirus 2009″. For those of you who would like to see the grisly details Wikipedia have an article about this nasty program [2] HERE.

In order to get this onto people’s computers the developers resort to some pretty impressive social engineering.

Firstly, a warning appears that your computer is infected with x number of infections.

Secondly, you are offered a free scan which will remove these infections. (This should set warning bells off given that you have an anti virus program already installed!)

Thirdly, in order to do this scan you have to OK a small add on download - you know the type, a little yellow bar appears at the top of the window saying something about an Active X thingy.

Befroe you know where you are you have installed Antivirus 2009 which looks very professional and even copies the AVG logo somewhat. See the screen shot below.

It is professional too! After all, it disables your existing anti virus program and starts downloading other nasties and all without you doing anything else. Before you know where you are your computer is unusable due to all the other programs running on it and everything on your computer is at serious risk.

The salutory example then? Simple, if anything pops up while surfing do not just click, no matter how convincing or persitant it is. If in doubt (or if it won’t go away) shut down Internet Explorer and run a full anti virus scan of your computer. While you’re at it empty the browsing history in Internet Explorer by clicking on Tools > Delete Browsing History > Delete All.