Security vendor McAfee published a detailed report on Tuesday about a hacking group that penetrated 72 companies and organizations in 14 countries since 2006 in a massive operation that stole national secrets, business plans and other sensitive information.

McAfee said the attackers are likely a single group acting on behalf of a government, differing from the recent wave of less sophisticated attacks from cyber activist groups such as Anonymous and LulzSec, according to the report.

McAfee did not say what country might have been working with the hackers, in contrast to companies such as Google, which as recently as last month blamed China for hacking into the Gmail accounts of several high-profile U.S. officials.

The intrusions, which McAfee called Operation Shady RAT, was discovered after the security vendor gained access to a command-and-control server that collected data from the hacked computers and logged the intrusions.

"After painstaking analysis of the logs, even we were surprised by the enormous diversity of the victim organizations and were taken aback by the audacity of the perpetrators," wrote Dmitri Alperovitch, vice president of threat research at McAfee, and author of the report.

Alperovitch wrote that over the past five to six years there has been nothing short of a "historically unprecedented transfer of wealth" due to the hacking operation.

The data stolen consists of everything from classified information on government networks, source code, e-mail archives, exploration details for new oil and gas field auctions, legal contracts, SCADA (supervisory control and data acquisition) configurations, design schematics and more, Alperovitch said.

McAfee declined to name most of the organizations attacked, referring to businesses such as "South Korean Steel Company," "U.S. Defense Contractor #1" and "Taiwanese Electronics Company," among others.

Those that were named include the International Olympic Committee (IOC), the World Anti-Doping Agency, the United Nations and the ASEAN (Association of Southeast Asian Nations) Secretariat. Those organizations, however, were not of economic interest to hackers, and "potentially pointed a finger at a state actor behind the intrusions," Alperovitch wrote.

The hacking group gained access to computers by first sending targeted e-mails to individuals within the companies or organizations. The e-mails contained an exploit that, if executed, would cause the download of a piece of malicious software that communicates with the command-and-control server.

In 2006, eight organizations were attacked, but by 2007 the number jumped to 29 organizations, according to the report. The number of victimized organizations increased to 36 in 2008 and peaked at 38 in 2009 before starting to fall, "likely due to the widespread availability of the countermeasures for the specific intrusion indicators used by this specific actor," Alperovitch wrote.

The duration of the compromises ranged from less than a month to up to more than two years in the case of an attack on the Olympic committee of a unnamed nation in Asia.

John Ribeiro covers outsourcing and general technology breaking news from India for The IDG News Service. Follow John on Twitter at @Johnribeiro. John's e-mail address is john_ribeiro@idg.com