Meanwhile, Intego's VirusBarrier Plus was holding down the No. 78 spot on Wednesday, down from its peak of No. 17. The $9.99 app has been on AppShopper's for just one week.

Kaspersky's Virus Scanner, which also costs $9.99, is at No. 90, and reached a high of No. 73 in the seven days it's been on the list.

The spike in downloads and sales didn't surprise Stephen Baker, an analyst with the NPD Group, which tracks retail software sales in the U.S.

Although NPD doesn't have sales data on Mac antivirus software during the last week -- it takes the company longer than that to acquire and compile the numbers -- Baker said there's a strong link between security threats and sales.

"Historically, we have always seen a jump in security sales that correlate to highly publicized security issues," said Baker in an email reply to questions. "[But] the spike seems to be declining over the years as more consumers use and recognize the importance of security software."