If you run OS X and want to check for the presence of Trojan-Downloader:OSX/Flashback.I malware, do the following:
Start up the terminal (from Finder, Cmd-Shift-A, click on Utilities, then on Terminal).
Open a new window (Cmd-N).
Copy-paste the following, followed by a return:
defaults read/Applications/Safari.app/Contents/Info LSEnvironment || defaults read ~/.MacOSX/environment DYLD_INSERT_LIBRARIES ||echo"You're OK" If you get a reply that ends with You're OK, then so you are.