The percentage of new web sites harbouring malware and other potentially unwanted programs has increased by almost 50 per cent this month, according to the latest figures from security firm MessageLabs released today.

The firm's latest monthly Intelligence Report also found that the number of phishing emails grew from 14 per cent to 59 per cent of all email-borne malware threats intercepted in October.

"Fortunately firms are becoming more aware of the threats and are spending more money on the right countermeasures, but the bad guys always seem to know a lot more," said MessageLabs' anti-virus technical architect, Maksym Schipka.

Spam dropped slightly by less than one per cent, but MessageLabs reported an increase in spamming activity exploiting hosted services.

The number of spam blogs on Google Blogspot and spam sent using fake MobileMe accounts increased, partly due to spammers gaining easier access to tools that can subvert Captcha (Completely Automated Public Turing Tests to tell Computers and Humans Apart) anti-spam techniques, said Schipka.

He advised firms to employ rate-limiting techniques to provide an extra layer of defence against spam. This ensures one IP address can only register a limited number of email addresses.