Has my browser been hacked?
When I opened an email from someone I don’t know, my web browser was taken to their home page on Facebook. Now when I try to open Facebook in that browser, it goes straight to that same page, not my own. Has my Mac or web browser been hacked?
This is most likely just your browser autocompleting the same address repeatedly, rather than anything more sinister. All the same, you’re right to be very cautious about what’s happening.
First, clear your browser’s history, to ensure that it doesn’t decide that you want to view this person’s home page ever again. You can do this selectively just for Facebook. In Safari, for example, choose History > Show History, then type in the web address ( facebook.com) in the search bar at the top right of the page that opens. Select all the results, then press delete to remove them from your browsing history. When that’s done, try entering Facebook’s web address again; with no Facebook pages in your history, the site’s front page should appear, not the unwanted one.
Also check for any extensions or plugins which might be hijacking your browsing. You should see those listed in your browser’s preferences. Also check the folders where those items are stored: in ~/Library (~ being your user’s Home folder), examine Internet Plug-Ins, and Safari/Extensions if you’re using Safari. Third–party browsers normally keep files in their own Application Support folder.