Yahoo Search Redirect Browser Hijackers on Mac
Yahoo Search Redirect is an umbrella term given to a number of different browser hijackers and potentially unwanted applications. It should be noted early on that the browser hijackers and PUAs associated with the term have nothing to do with Yahoo! Inc and Yahoo on its own is a legitimate search engine and website.
The way browser hijackers that are bundled together under the definition "Yahoo Search Redirect" PUAs work is, they simply use Yahoo's platform to feed the final results page to the user. However, the URL you will see once you hit the results page is modified and is not the same URL you would get from a Yahoo search using the same query.
Your search is first bounced through a number of other domains before you are served with the Yahoo results page. In this way, your search queries are exposed to third parties and are used for monetization purposes by those third-party platforms. The modified appendix of the Yahoo search URL will usually vary, depending on which specific browser hijacker you have on your system that uses Yahoo's search as its ultimate destination.
Additionally, the browser hijackers that serve results using Yahoo's platform will change your browser's search engine to their own. Your home page will also likely get replaced by one used by the specific hijacker that uses Yahoo search. Both those things happen without user consent and it can sometimes be impossible to revert your search engine and home page to your original defaults, depending on how good the persistence mechanisms of the potentially unwanted app are.
A couple of examples of potentially unwanted applications that will ultimately serve modified Yahoo result pages include TapuFind and SafeFinder. A lot of the browser hijackers that use Yahoo search will also inject additional advertising in your result pages that will not be there on a regular Yahoo search using the Yahoo engine directly, without all the redirects associated with the PUAs.
The most common way similar browser hijackers are distributed is through bundle installers or bundlers. Those are software installers that include several apps, with one headlining, often legitimate application, and one or more potentially unwanted apps piggy-backing inside the installer. The PUAs contained in those bundle installers usually don't disclose their presence adequately and install quietly, without explicit user consent and knowledge.
Sourcing your software and apps from legitimate, curated platforms instead of any random free download site you run into is the best way to steer clear of similar potentially unwanted apps.
