Criminals are using underground economy servers to sell stolen information, including credit and debit cards, PIN numbers and user account details, according to the latest report by Symantec.

Over half of the servers (51 per cent) discovered during the six month analysis were located in the US. American credit cards were available to buy for between $1 (51p) and $6 (£3), while an identity, including a bank account, date of birth and government issued identity number, was on offer for approximately $18 (£9).

The global study, which was conducted between July and December last year, also found that online hacking attacks are becoming increasingly coordinated, resulting in a convergence of bots, phishing, spam and Trojans to seize sensitive data. Spam made up 59 per cent all monitored email traffic during the second half of 2006.

“Hackers are using an increasingly sophisticated array of techniques in order to steal confidential information,” said Ollie Whitehouse, security researcher at Symantec. “Whereas, historically, threats were based around only one or two methods of stealing data, attackers are now using multiple attack techniques.”

The number of active bot networks and Trojans both jumped, by 11 per cent and 22 per cent respectively, the latest figures show. More than six million computers world wide are now part of a bot network, which indicates that hackers are switching tactics away from mass-mailing worms, the report said.

Phishing attacks also rose over the past six months. A total of 166,248 unique phishing messages were detected during this period, an increase of six per cent. This accounts for an average of 904 new phishing emails per day.

The analysis found that more than half (54 per cent) of all identity theft-related data breaches could be traced back to the theft or loss of a computer or other removable storage device. Inadequate security policies caused 28 per cent of data breaches which resulted in identity fraud.

“The criminal fraternity has recognised that there’s significant profit to be made by turning their attentions online and are constantly evolving their techniques in an effort to outwit businesses and consumers,” Whitehouse warned.