Nearly a third of cyber attacks spawned in USA

US networks pumped out the highest percentage of attacks during the second half of last year, with China running a distant second, according to a report released by security company Symantec.

The US accounted for 31 per cent of malicious activity originating from computer networks, while 10 per cent came from China and seven per cent from Germany, Symantec said in its Internet Security Threat Report.

The company also found that 51 per cent of all known servers used by attackers to buy or sell stolen personal information, such as credit card or bank account numbers, are located in the US.

US-based credit cards, with accompanying verification numbers, were found to be selling for $1 to $6 each on these servers. But a more thorough round-up of personal-identification data - including a person's birth date and banking, credit card and government-issued identification numbers - fetched $14 to $18, the report noted.

Internet thieves are increasingly turning to Trojan-horse software, which can load keylogging software onto unsuspecting victims' computers. The software is able to harvest people's login names and passwords to various accounts and can glean other sensitive information people type into their computers.

Trojans accounted for 45 per cent of the top 50 malicious code samples collected by Symantec during the second half of last year, up from 23 per cent in the previous six months. Symantec noted that that significant jump further reflects a movement away from mass-mailing worms.

Phishing largely occurs during the weekday, the report noted. Many phishing attacks begin with an email that appears to be from a legitimate source but in fact contains a malicious attachment or includes a link to a malicious website. During the second half of the year, a daily average of 961 phishing emails were sent to people on weekdays, while 27 per cent fewer phishing messages were sent out on weekends.

Dawn Kawamoto writes for CNET News.com