Nine in ten emails are now spam with an estimated 200bn junk mail messages a day clogging up the internet, according to a new report by networking and security giant Cisco.
Drive-by download attacks - planting redirection scripts on legitimate sites that lead onto hacker controlled websites full of exploits - have become a popular method for spreading all forms of malware, including botnet clients that turn PCs into spam-churning zombies.
The US is the single biggest source of spam, accounting for 17.2 per cent of junk mail. Other big offenders include Turkey (9.2 per cent), Russia (8 per cent), Canada (4.7 per cent), Brazil (4.1 per cent), India (3.5 per cent), South Korea (3.3 per cent), Germany and the UK (2.9 per cent each).
The latest 2008 edition of Cisco's annual security report notes a 90 percent growth in threats stemming from legitimate domains, nearly double that recorded in 2007. Numerous mainstream websites were loaded with iFrames, malicious scripts that redirect visitors to malware-downloading sites.