Cybercriminals have been increasing the effectiveness of their individual outreach by creating multi-stage, also known as blended, attacks, which combine messaging and Web elements, according to Internet Threats Trend Report by Commtouch.

The report said that these perpetrators are using email or search engine results to lure victims to sites hosting spam advertising, malware, or phishing.

During Q2 2010, Gmail and Yahoo topped the list of spoofed domains for email distribution, and they have been joined in the top six by Twitter.

Commtouch said that spam levels averaged 82% of all email traffic throughout the quarter, bottoming out at 71% at the start of May and peaking at nearly 92% near the end of June.

These numbers are slightly lower than those detected in Q1 and equate to an average of 179 billion spam messages per day, the report added.

The report found that an average of 307,000 zombies were activated daily to inflict malicious activity, representing a slight increase over the prior quarter.

Pharmacy spam retained the top spot with 64% of all spam and pornography remained the Web site category most infected with malware.

According to Commtouch, TDSS.17 was the most widely distributed email-borne virus, but the Mal/Bredo malware had the most variants – over 1800. India accounts for 13% of the world’s total zombies and has surpassed Brazil.

Asaf Greiner, vice president of products at Commtouch, said: "Cybercriminals have been forced to change their techniques to evade improved detection technology. Complex multi-stage attacks with improved social engineering are proving to be the preferred technique."