Thirty-five percent of all Internet intrusion attacks are coming from Korea, according to a new study released today by Network Box. Analysis of all Internet threats in November by the company shows that Korea accounts for more than double the intrusions of its nearest competitor, the U.S. (14 percent).

Spam and viruses are on the decline from the U.S., following the shutdown of the McColo spam hosting service earlier this month, Network Box says. During the full month, the U.S. was the biggest source of spam and viruses, but the figures dropped sharply toward the end of November, when China took the top spot in the spam charts.