StatefulFirewall Browser Hijacker
StatefulFirewall is a browser-hijacking extension that can implant itself inside your Safari browser.
The extension behaves like a browser hijacker, which is a type of potentially unwanted application. Once installed, StatefulFirewall will change your browser's default search engine and your home page.
This happens without asking the user for explicit consent and the changes are made "quietly", which is typically classified as potentially unwanted app behavior.
In most cases, similar browser-hijacking extensions are distributed through software bundles. You may have downloaded a package off a free download website that does not monitor its contents properly. Sometimes a potentially unwanted program like StatefulFirewall will be bundled with one or more other, possibly legitimate applications and will install quietly alongside the rest.
If you find StatefulFirewall among your browser's installed addons and extensions, you should remove it to restore your browser to its default state and normal working order.