There are a variety of toolbar utilities and enhancements that are available for Firefox, Safari, and other Web browsers. Most of these are implemented as plug-ins for the browsers that can easily be disabled, but some developers make these additions rather difficult to detect and uninstall. Apparently, a number of people have been frustrated by a plug-in that was developed in this way, which changes Safari's default search engine to "Fast Browser Search," with no obvious way to change this back.
The problem is basically that searching in Safari goes to the "Fast Browser Search" site instead of using the default "Google" engine, and has started after installing various Web utilities such as toolbars and social networking plug-ins. As such, while some may regard this as malware, it is, in fact, a user-installed option that might more appropriately be called "annoyware." It was developed for legitimate purposes by Make The Web Better, LLC, but is packaged in a way to prevent easy uninstallation (like just removing a plug-in).
The Fast Browser Search addition is managed by a user-based launch agent, which targets and launches the add-on every time the user logs in. As a result, even if you have an empty plug-ins folder, your browser will still use the Fast Browser Search site. To remove the software, you will need to locate and delete the "MTWB" folder from the /username/Library/ directory. This folder contains the program files that are being launched, but in addition, you may also choose to delete the launch agent property list that is responsible for configuring the automatic launch of the program. This file is called "com.MTWB.Product.plist" and is located in the /username/Library/LaunchAgents/ directory.
Once these files are removed, log out and log back in to return Safari and other browsers to their default search engines.
We thank MacFixIt reader "Jon" for bringing this to our attention.