"We've seen a substantial increase in both sales and downloads of trial versions of our software," said Peter James, a spokesman for French security company Integra. "Part of this is certainly due to Flashback."

Intego, which develops and sells only Mac antivirus software, is best known for its $49.95 . A 30-day free trial of the software is also available.

James did not provide sales figures for Intego's security software, or specify the increase his company has seen since a Russian antivirus firm said more than 600,000 Macs had been infected with Flashback, many of them in a recent campaign that exploited an at-the-time-unpatched vulnerability in Oracle's Java.

Another security provider echoed James.

"It would be true to say that we have seen a rise in the download rates of our free antivirus for Mac home users," said Graham Cluley, a senior technology consultant with U.K.-based Sophos.