MessageLabs has warned that the spam and phishing epidemics could spread, as its latest monthly intelligence report found levels of unsolicited mail continued to rise while viruses dropped in volume.

Chief security analyst at the firm Mark Sunner explained that spam levels have been driven by the activity of more robust botnets that are capable – thanks to Trojans such as SpamThru – of sending out a larger volume of spam.

"Few people realise that spam traffic levels are not linear, they're very spiky, so these botnets are not being used to capacity – all the evidence we have would indicate that we're looking at the thin end of the wedge in terms of volumes," he said.

Phishing attacks are also continuing to rise because the email channel is largely "buttoned down" according to Sunner. He added that attacks are also becoming more sophisticated, for example the criminals are now using man-in-the-middle attacks to circumvent the two-factor authentication methods now employed by many organisations, such as PayPal.

Separately, web security services provider ScanSafe released its annual threat report last week, warning firms that the potential risks from users browsing the web are higher than ever before.

The firm found that one in five internet searches generates inappropriate or malicious content, while up to one in 600 social networking pages contains malware. "In 2007, the notion of real-time scanning of content will be important," argued ScanSafe's Dan Nadir. "Everyone thinks that you can pre-populate a database with known malware sites but you can't say MySpace as a whole is a bad site, for example."