Millions of poorly secured PCs have become infected with a computer worm, it has been revealed.
The malware, known as Conficker, has been attacking computers through low security networks, USB sticks and PCs which haven't been updated with the latest Windows patches.
Microsoft has issued a security patch but, according to the BBC, were not quick enough to stop millions of computers becoming infected.
Once your machine is infected, the malware gets to work on your system, downloading hacker files to your computer and masking the hackers real homepage among thousands of randomly generated HTTP addresses.
This makes it much harder for anti-virus programmers to track the source of the hack down.
Hard to defend against
The malicious program has been around for a few weeks now, with those in the computer security industry already aware of the havoc it can cause.
TechRadar spoke to Jacques Erasmus, director of malware research at Prevx, and this is what he had to say: "Conficker is interesting. We first saw it 31 December where our heuristics caught it. Since then it's gone on to infect a lot of machines.
"I respect the mechanism it uses to choose a URL to communicate with every few days. It makes defending against this type of attack on a network level much harder."
According to F-Secure, in the UK so far 1,789 machines are known to be infected. The country with the worst computer casualties is China, who has seen 38,277 PCs infected with Conficker.