Angelina Jolie pictures trigger malware surge

The jump is attributed to a hacking campaign using the Pushdo Trojan during the second half of September.

Messages promising images of actresses such as Halle Berry and Jolie, were sent to recipients with malware designed to give the hackers control of infected computers.

According to Sophos, the Pushdo Trojan accounted for nearly four in every five malicious emails during a single 24-hour period last month.

"The Pushdo Trojan has been spammed out every Wednesday since March 2007 using a variety of enticing disguises,” said Carole Theriault, senior security consultant at Sophos. “But lately, the cyber criminals have stepped up a gear and have begun to spam innocent computer users at any time and on any day of the week."

The figures reveal that one in every 833 emails were infected with a malicious attachment compared to one in every 1,000 during August and Sophos detected 5,400 new webpages hosting malicious code each day last month.