The Sunnyvale, California-based white label IT security firm says the surge in successful malware attacks logged in its Q2 2009 Internet Threat Trends Report has caused a spike in the number of high-profile infections during the period.

According to CommTouch, spammers and malware distributors have used a number of current events including the swine flu epidemic and the recent tragic death of Michael Jackson to spread their messages.

Interestingly, CommTouch says that sites in the `health' and `web-based email' categories topped the list of web categories manipulated by phishing schemes. The term `business' in particular was the website category most infected with malware.

Delving into the report reveals that an average of 376 000 zombies were newly activated each day for the purpose of malicious activity.

Image-based spam, meanwhile, returned with new tactics foregoing MIME-format standards to trick anti-spam engines.

The report notes that spam levels averaged 80% of all email traffic throughout the quarter, peaking at 97% in April and bottoming out at 64% in June.

Amir Lev, CommTouch's chief technology officer, said that Brazil continues to produce the most zombies, and is responsible for 17.5% of global zombie activity.

For the last year and a half, anti-virus engines effectively blocked many virus variants with generic signatures, he noted.

"In the second quarter, however, malware distributors introduced large quantities of new variants which are immune to these generic signatures, therefore causing sharp increases in undetected malware samples that were blocked by CommTouch", he said.