A 16-fold growth in malware and a proliferation of spam were two of the greatest security problems facing the internet in 2007, according to an end-of-year report from management software vendor CA.

The notable growth in malware took place between January and October of last year, aided by the abundance of spam. For the year, over 90% of email was spam, and eight in 10 spam emails contained links to malicious sites or malware.

Spam also became more difficult for users to detect. In the report, CA wrote: 'The quality of spam has improved and is no longer obviously riddled with typos. It is also laden with attachments-images, PDFs, documents, spreadsheets or videos-that have malware or link to malicious sites.'

The type of malware changed too. Malicious spyware surpassed Trojans to account for 56% of malware. Worms represented 9% of malware, and viruses formed 2%.

The most common types of spyware were adware, Trojans and downloaders. But rogue security software, distributed via online ads for free anti-spyware software, also became a visible problem.

The UK was a major malware target, alongside France, Germany and Australia, but the U.S. was the country most barraged, receiving 40% of spam.

CA predicts that this year cybercriminals will send smarter malware that is able to target virtualized machines and will cause more damage to Microsoft Vista users, Web 2.0 sites will be the victims of better targeted attacks, and botnets will affect more computers than ever before. The U.S. presidential election and Beijing Olympics would be "high profile opportunities" for attacks and information theft, CA said.

Meanwhile, an end of year report by the AVG Research Team reveals viruses made up some 15 percent of the threat landscape in 2007. It said the top three viruses were W32/Detnat, W32/Netsky and W32/Mytob. Phishing scams, backdoor worms, Trojans, keyloggers, spyware, adware and other web-based exploits comprised the majority of threats, according to AVG.