1. Open Finder.
2. Go to Applications
3. You'll see an app called "Reset Search" Alternatively there may be a folder called "InstallMac". Drag it to Trash and empty Trash
4. Open Chrome. Go to Settings
5. Click the button called "manage search engines" and make Google the default. Then click the cross to remove "search the web"
6. In Chrome Settings under "Appearance" click "Change" and then set "Use the new tab page." Also in the "On Startup" section ensure you delete the searchbenny page. and then set to "open a new tab".
7. In Safari open Preferences and head to "General Settings". Change your default engine (IMHO bing is better than Google). In newer Safari versions you can do this in the "Search" tab. Also remove all garbage from the "Manage Websites" section.
8. Set the homepage to "http://www.apple.com/startpage/" Alternatively open "Top Sites" in a new tab and use that by selecting "Use Current page"
9. Open "Activity Monitor" - Quit the "InstallerT" process.
10. You're set. Just some malware. No permanent damage. All it did was change your search defaults.
Had to post using a different account cause HN says I was submitting too fast.