Adobe update, or The Trojan?

Go to System Preferences->Flash Player->Advanced.

Under the Updates note the current version and then

click Check Now. If the version posted on the official

Adobe Flash page is different, then download and install

the update from Adobe.

You can then go back to the Adobe preferences an select

the "Never check for updates". Then, if you get a request to

download and install, you will know it didn't come from Adobe.

If a site claims you need to update, you can then just go

to the Flash Player preferences again and manually do a

Check Now. If the versions are identical, then you know the

request was fraudulent and avoid that site like the plague in

the future.

The Flashback trojan doesn't have anything to do with Acrobat Reader, though it's still wise to be concerned about such things. Check for updates manually in Acrobat Reader, or just manually download the latest version directly from Adobe's web site. As woodmeister50 says, you can turn off update checking, but the downside to that is that you may miss out on an important update. Both Flash and Acrobat Reader have been known to suffer from vulnerabilities that need to be fixed ASAP, lest the user become victim to something like Flashback. (Flashback used a Java vulnerability, not one in Flash or Acrobat, but the same idea applies.)

Regarding anti-virus software and other similar issues, see my Mac Malware Guide.

(Note that my pages contain links to other pages that promote my services, and this should not be taken as an endorsement of my services by Apple.)

The only Flash you should ever install is from http://www.adobe.com/ If you get a popup window asking for Flash, contact the webmaster of the site in question and tell them to stop allowing that advertiser to make such popups, or you won't browse that website.

The difference between the Trojans masquerading as Flash and the real one is how they are presented on your desktop.

The Trojan always appears directly from a web page. The real Flash update box appears on your desktop separate from any web browser and can appear at any time. Including if you have no browser open at all.

If you want to avoid confusing the two, open the System Preferences and click on the Flash Player icon. Under the Advanced tab, choose the radio button for "Never check for updates (not recommended)". Anything claiming to be a Flash update after that you will absolutely know is a fake. The downside is you have to remember to manually check to see if there are any real Flash updates so you keep on top of any fixes Adobe has released.