A study of Internet threats by Network Box found 15.9 percent of all viruses originate from the US last month, closely followed by Brazil with 14.5 percent. The latter country is the largest source of spam, producing 11.6 percent of all junk e-mail, followed by the US at 8.6 percent and South Kore at 7.2 percent. The security firm's analysis also found that South Korea remains the biggest source of intrusion attacks, at 17.3 percent.
Network Box claims malware volume is down again to levels seen in June, and that spam levels are also down since their peak in May.
Mark Webb-Johnson, CTO of Network Box, said: "The large number of recent vulnerabilities announced by both Microsoft and Apple led to a frenzy of malware activity spearheaded by an unprecedented large number of website defacements. What we're now seeing is that those who have already patched are protected and those that haven't are already infected -- so the number of new infections appears to have levelled off."
Simon Heron, Internet security analyst for Network Box, added: "Businesses and individuals still need to be alert to threats through the remainder of the summer, particularly phishing attacks. We've seen a huge increase in SQL injection attacks so it's important that anyone using Web-based applications or servers keeps their security up-to-date."