The Spam Report, May 2009

One of the most startling trends this month has been the rise in image spam, which now accounts for 16% of all unwanted messages

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By  Vineetha Menon Published  May 10, 2009

One of the most startling trends this month has been the rise in image spam, which has jumped in recent weeks to now account for 16% of all unwanted messages.

Image spam by definition is a message that contains an attached image with little or no text. While it might not seem to cause much harm, it does strain mail infrastructures because of its relatively larger message size and could even prevent users from receiving legitimate emails.

In 2007, 52% of all spam was categorised under image spam but it subsequently went into an obvious decline. Now however it’s jumped to hit an average 16% of all spam messages, Symantec’s May State of Spam report revealed. That’s not all – an increase in the average size of spam messages has also been noticed, which spells more trouble for weaker mail infrastructures.

Despite mail providers using effective anti-spam filters, image spam is still thriving today because attached images often make use of subtle changes to the colour, font and background noise to evade anti-spam detection.

Moving away from that category and looking at the spam landscape a whole, Symantec have reported that spam volumes are now currently at 94% of pre-McColo levels. Late last year, spam levels dropped to historic lows when McColo.com, suspected of hosting a large number of botnet control system, was brought down. In fact, there was a 65% drop in traffic compared to just 24 hours before the shutdown.

Spam categories are showing growth variations every month with leisure and internet spam decreasing 8% and 7% respectively in April, and finance-related spam increasing by 6%.

Health-related spam definitely got the most attention as news of the Swine flu spread faster than the virus. Observed spam samples included messages discussing medicines that could be used to fight the flu with URLs that connect to various pharmacy sites. In other examples, potential victims were sent an email with a malicious PDF attachment that promised to answer questions about the H1N1 virus and instead infected machines with malware.

While fears about the virus slowly dissipate, spammers will likely move on to the next big scare or trend to lure more victims.

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