14 DAY TRIAL // Google reports that the overall number of infected emails grew by 42% during the last quarter, but a massive surge was observed during August in particular.
According to data gathered via its Postini email security and archiving services, spam levels decreased by 16% during Q3 compared to the previous quarter and by 24% compared to Q3 2009.
This might be temporary though, because a spike in email-based malware distribution campaigns during the same period is likely to have infected a lot of users with botnet clients.
The number of emails carrying malicious payloads during the last quarter was 10% higher than in Q3 2009 and 42% bigger than in Q2 2010.
August was the most active month in this respect, with a whooping 241% increase over July, which according to Google is the greatest surge in this type of activity since 2008.
August was also the month with the highest ever recorded number of email-borne viruses blocked in a single day – 188 million.
"This recent increase in viral activity could indicate a 'gearing up' as spammers attempt to construct botnets in time for the holiday season and increased consumer spending.
"With the commercialization of spam in 2006, we’ve often seen a correlation between spam, malware campaigns, and seasonal consumer patterns," the Google Postini Services Team, explains.
Many of the infected emails posed as communications from well known companies and services, but Google's researchers have also observed a new technique of reusing content from emails already found on the victim's computer.
This method emulates emails sent by real humans and is a lot harder to detect for anti-spam filters. It can have more success in infecting victims, since the emails look familiar.
"Overall, virus traffic continues to be strong and users need to be on high alert when handling suspicious messages," the Google researchers advise.