Windows computers affected by virulent form of ransomware

According to a report by security researchers a virulent form of ransomware has now infected about quarter of a million Windows computers.

Cryptolocker scrambles users' data and then demands a fee to unencrypt it alongside a countdown clock.  

Dell Secureworks said the US and UK had been worst affected.  

It added that the cyber-criminals responsible were now targeting home internet users after initially focusing on professionals.  

The firm has provided a list of net domains that it suspects have been used to spread the code, but warned that more are being generated daily.