New botnets have emerged from the taking down of ISPs hosting botnet activity in the last year, according to Symantec.
Botnets are now responsible for sending 87.9 per cent of all spam, with a newer botnet called Maazbem experiencing rapid growth in May by spewing out casino-related spam emails, according to a MessageLabs Intelligence Report.
Maazben's growth has accelerated over the past month, from 0.5 per cent of all spam in August to 1.4 per cent of all spam in September.
Paul Wood, MessageLabs Intelligence senior analyst, said in a statement that the number of ISPs being taken offline for hosting botnet activity had resulted in a case of older botnets sinking and newer botnets taking their place.
He said: "This has undermined the power of the more dominant botnets like Cutwail and cleared the way for new botnets like Maazben to emerge."
However, one of the oldest and largest botnet, Rustock, had doubled in size since June - it's the only botnet to have a regular spam cycle.
Research published this month also claimed that the decline in domain tasting the practice of cancelling domain registrations within five day grace period had changed the malicious nature of websites.
The research reported that malicious domains were now likely to be older, compromised websites rather than newly registered domains with a short lifespan as was the case a year ago.
Click here for Davey Winder's view on the MessageLabs report.
