The report, released earlier this month by McAfee, claimed that a hacker operation compromised more than 70 U.S. and foreign government agencies, defense contractors and international organizations to plant malware that in some cases hid on networks for years.

McAfee's report was picked up by numerous news outlets, and even caught the eye of Congress. On Aug. 10, Rep. Mary Bono Mack (R-Calif.), the chairman of the House subcommittee on commerce, manufacturing and trade, sent a letter ( ) to McAfee asking for more information on the intrusions.

McAfee dubbed the campaign "Shady RAT" and said it was an example of an "advanced persistent threat," or APT, a term that's been used widely by mainstream security companies, and in news reports, since Google claimed that Chinese hackers had breached its network.

Last Thursday, the CEO of Moscow-based Kaspersky Labs took exception to McAfee's conclusions, especially that the attacks were sophisticated enough to justify the "advanced" part of the APT label.

"We consider those conclusions to be largely unfounded and not a good measure of the real threat level," said Eugene Kaspersky, CEO and co-founder of the company that bears his name.