China's rapid Internet growth has brought with it a somewhat disturbing side effect: multiplying zombies up to no good.

Zombies, or internet-connected computers infected by worms or viruses and under the control of a hacker, are used to launch denial of service (DoS) attacks, or send spam or phishing emails. An average of 157,000 new zombies are identified each day, and 20 percent of these are in China, security company CipherTrust reported this week.

"It shocks me that the numbers are so high," says David Stanley, CipherTrust's vice president and managing director for Europe, the Middle East, and Africa.

CipherTrust analyzed emails collected throughout March and the first half of April from customers worldwide. It found that 57 percent of spam originated from the US, down from 86 percent during June and July last year.

The decrease in spam from the US and increase in zombies in China was not necessarily a surprise, Stanley says.

"Criminals look for a weaker link, so places like China, or anywhere behind the US in terms of computer literacy, are a good target," Stanley says.

China's fast-growing internet population is also an attraction, he says. As of January, there were 94m internet users in the China, up 18 percent from the year before, according to the China Internet Network Information Center (CNNIC).

Hackers are moving their spam-sending efforts to emerging markets that don't have as many internet security measures in place, or high levels of user education, Stanley says.

South Korea is the second-largest source of spam, delivering almost 16 percent of unwanted email, CipherTrust says. That figure is up 13 percent from eight months ago, it says.

To thwart an army of zombies invading their countries, emerging markets should try to learn quickly how to educate and protect internet users, Stanley says.

"It's very important that we learn from experiences we've seen in other areas," he says.