Finder shows strange letter and number codes instead of usual names for folders and stuff.

Could be that somehow the fonts used for displaying this info has been corrupted. You might want to think about reinstalling the operating system.

You can do that right over the top of the current install and it won't remove any of your files or programs.

The button labels in my folders are...: Apple Support Communities

You may have recently installed what you thought was a Flash update. Do you know where you got it? Don't post the link here.

If you know where you got it, please contact me privately so that I can investigate it. It sounds like there may be a new variant of Flashback out there, and if that is indeed the case, we need to ensure that the anti-malware community is made aware.

It would not have come through automatic software updates. Did you see something like what is described here in Flashback.A seen in action!?

Edit: Alternately, there is a recently-discovered variant of Flashback that can sneak in without user interaction, if you have an outdated version of Java installed. What version of Java do you have? Try typing "java -version" in the Terminal (found in /Applications/Utilities) and paste the results back here. If you get an alert that you don't have Java installed, that prompts you to install it, that means you don't even have Java installed and are thus safe.

That could be your problem... The most recent version of Java available is 1.6.0_29. You should get that if you run Software Update and allow it to install any Java updates, but if you don't, you can download it manually for Mac OS X 10.6 from:

http://support.apple.com/kb/DL1360

Of course, installing that now may be a bit like closing the barn door after the horses are all gone. You may be able to remove the malware using the instructions here:

http://www.f-secure.com/v-descs/trojan-downloader_osx_flashback_c.shtml

However, that is for an older variant of Flashback, and not enough is yet known about the variant that uses Java vulnerabilities to know whether those instructions are adequate.

For more information about this variant, see Flashback using Java vulnerabilities. (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.)

cecyy wrote:

should I still be concerned about removing the malware?

Yes, but none of the articles I've read on this latest version have described where it is, how it works or how to remove it. Unless I can get my hands on whatever it was that caused this for you, I can't give you much advise. If it's the same version that Intego found here, you might want to use a trial version of Virus Barrier X6 to see what it can find. If it's new today, then even that may not work.

If you find a recent installer package for FlashPlayer on your hard drive, let me know and I'll give you a couple of places to upload it to that will get the AV software folks busy on updating their definitions.

Found some clues tonight on a couple of the other files involved at https://discussions.apple.com/thread/3751817.