The number of malicious websites blocked each day has risen by 58 per cent last month to its highest level since April 2007, according to MessageLabs.
The vendor's Intelligence Report for Q2 said that there was an average of 2,076 new websites each day which carried malware and other programs such as spyware and adware.
Message Labs said that the figure indicated that cybercriminals were taking full advantage of computer users with web-based malware. Many did not understand the risks, with web applications vulnerable if security wasn't good enough.
"Businesses that allow employee access to any website and sites with webmail accounts that haven't been scanned by corporate security systems are at particular risk," said Mark Sunner, chief security analyst at MessageLabs.
The quarter also saw Storm botnet numbers continue to decline in volume, from 20 per cent of all spam in the first quart to five per cent now. Srizbi kept its crown as king of the spam botnets, accounting for 40 per cent.
Almost a quarter (74.3 per cent) of all email in the UK was spam, with one in 86 emails carrying a virus. The number of phishing attacks did not change much in June compared to the previous month, but the organisations it was targeting had widened to include recruitment agencies and online retailers.
