Malicious spam volumes increased dramatically in the back half of 2009, reaching three billion messages per day, compared to 600 million messages per day in the first half of 2009. But this is still a tiny fraction of the estimated global spam volume, thought to be about 200 billion messages per day.
A new report
by net security firm M86 Security points the finger of blame for the torrent of malware, phishing and other scams (collectively defined as malicious spam) and junk mail more generally towards botnet networks of compromised machines. It reckons five botnets were responsible for 78 per cent of the malicious spam it fought in the second half of 2009.