Jun 1, 2011 17:11 GMT  ·  By

A listed security firm specializing in malware targeting Mac OS X, Austin, Texas-based Intego has issued a note signaling that Apple’s latest security patch has a bug that can lead to badly adjusted security settings.

In what is clearly starting to look like a sloppy job on Apple’s behalf, Security Update 2011-003 not only fails to thwart one recently emerged Mac Defender variant, it also brings with it an error that can result in infection, Intego’s advisory suggests.

They explain that, “Following the release of the Mac OS X security update to protect against the MacDefender fake antivirus, Intego’s security researchers discovered an interesting bug with the Security preference pane.”

The security vendor acknowledges that Apple’s update delivers a new preference - “Automatically update safe downloads list”.

“This setting tells Mac OS X to check every 24 hours, and on each restart, for new malware definitions in addition to the few that are already available,” according to Intego.

“However, if you open the Security preference pane, unlock it, and wait for more than 30 seconds, any changes you make to this setting will not stick,” the Mac security specialist reveals.

If these conditions are met, quitting and opening the Security pref pane again will display unchanged settings, Intego says.

Their advice: “You should be aware that this bug may override settings you make to this preference, and if for any reason you’ve left the Security preference pane opened for more than 30 seconds, you should check again to see if the change you made has stuck.”

Intego is the first security firm to officially report on the existence of Mac Defender and the level of threat it posed when it emerged in its original form.

Since then, multiple variants have emerged, prompting Apple to take action.

With this apparently weak attempt to address malware risk on the Mac, the Cupertino, California based Mac is not leaving a very good impression.