CipherTrust says it has recorded a 21% increase in the number of new zombie computers and a 20% increase in overall unwanted email traffic over the past month.

Additionally, CipherTrust Research concluded that of all spam servers, 64% are located in Taiwan; 23% are located in the United States; and 3% are located in mainland China.

A zombie computer is a computer attached to the Internet that has been compromised by a hacker, a computer virus, or a trojan horse, and performs malicious tasks of one sort of another, under the direction of the hacker. Many owners of zombie computers are unaware that their systems are zombies or that any hacker attack ever occurred.

CipherTrust Research says it is able to determine the origins of spam servers using a combination of the company's TrustedSource reputation engine and a network of "fake" zombies deployed throughout the world. CipherTrust deploys a network of zombie-like machines across the world to gather intelligence on spamming operations.

While these fake zombies do not relay spam or phishing attacks to end users, they collect messages from spammers trying to exploit those machines and feed the information into the TrustedSource reputation engine for further analysis, including determining the physical location of the servers.