Hackers control networks of zombie computers, known as a botnet, in order to silently send out adverts that peddle adverts for sex drugs, financial scams, and malware that steal identities and even to launch denial-of-service attacks.
If you're not running a tight ship when it comes to computer security, then you could actually be adding to the problem.
And that's why it would be great if you checked this weekend if you have a zombie whirring away at home. It seems somehow appropriate considering it's the Halloween weekend.
Here's a video promoting the idea of International Kill-A-Zombie Day.
Zombie computers, or botnets, are truly a global problem -- and all of us can play a part in ensuring that the PCs we own, and those of our friends, are running the latest antivirus software.
Just take a look at the dirty dozen chart of top spam-relaying countries between July and September.
| The top spam-relaying countries in July-September 2009 were: | |
| US | 13.3% |
| Brazil | 12. 1% |
| India | 5.6% |
| S Korea | 5.5% |
| Vietnam | 4.7% |
| China | 4.0% |
| Poland | 3.9% |
| Turkey | 3.3% |
| Russia | 2.8% |
| Spain | 2.7 |
| Italy | 2.3% |
| Argentina | 2.1% |
| Other |
37.7% |
| Top spam-relaying continents (July-September 2009): | |
| Asia | 35.6% |
| Europe | 24.8% |
| S America | 19.6% |
| N America | 16.5% |
| Africa | 2.2% |
| Oceania | 0.7% |
| Unclassified | 0.6% |
Maybe using the medium of horror movies at this spooky time of year will wake people up to the danger that may lurk on their own PCs.
Graham Cluley is senior technology consultant at Sophos, and has been working in the computer security field since the early 1990s. When he's not updating his other blog on the Sophos website, you can find him on Twitter at @gcluley. Special to Dark Reading.