Most Internet users have gotten pop-ups with some variation on the message of “install Adobe Flash Player update” when visiting various websites. However, as easy as it might be to hit the “install” button, Graham Cluley’s alerted users to be very, very careful about doing so.

His recent article warns Mac users about the fake updates that have been found to be infecting computers (newsletter@grahamcluley.com; “Mac Users Attacked Again by Fake Adobe Flash Update;” April 12th).  Mr. Cluley cites the Intego security experts who detected the fake update package installer. Part of the difficulty for non-experts is that the scammers behind these fake updates have somehow gotten and are using a legitimate Developer ID certificate.

Why is that important? Because the Mac’s operating systems built in Gatekeeper security is fooled by this legitimate certificate — with the result that the malicious files get installed.

How to avoid this? Mr. Cluley’s article stresses that users should go to the Adobe website; that site has information about updates and allows users to know they’re installing the legitimate version. His article has links to other sources of very helpful background information about this very situation.

Finally,  Mac users also have the option of making a change on their computer. They can hit the Apple insignia in the upper left hand corner of the screen; go to “system preferences” and then choose among three different Adobe Flash Player options.

This is an important alert for which we have Mr. Cluley to thank.