If you want to add a little festive cheer to your computer, a screensaver showing beautiful Thanksgiving images might be just the thing.

But unfortunately, not all things downloaded from the Internet are safe to use, and cyber crooks love nothing more than to take advantage of popular holidays to saddle you with malware.

A screensaver named Thanksgiving Day.scr being currently offered for download is a prime example of how malware can be bundled up with seemingly innocuous software in order to fly under the users' radar.

Once run, the file does function as a screensaver, but it also silently connects to a website and tries to download a backdoor Trojan so that the malicious individuals behind the scheme can take remote control of the victims' computer.

The malware secures its presence and persistence on the machines by adding a DLL file to the Registry.

"The lesson, of course, is not to trust every program that you run into on the net, and think twice before installing code of dubious provenance. Don't think you can take a short cut and not worry about computer security just because it's Thanksgiving," Graham Cluley concludes.