The Hastopic website has been reported by many users to have appeared unexpectedly on their browsers. More specifically, the page appears to be primarily targeting Android devices and could be connected to malware infection or the presence of a PUP (Potentially Unwanted Program) on the device.
Indeed, users have seen Hastopic being set as their browser's homepage, being opened every time the browser is launched, etc. Hastopic may show intrusive advertisements, and, in some cases, users have even observed new applications being downloaded or installed on the Android device without their authorization. The last functionality could be extremely threatening, as the newly deployed applications may contain potent malware threats.
Typically, sites such as Hastopic are being injected into users' Web browsers via a browser hijacker application. These PUPs are capable of modifying the browser's settings and changing its homepage, new tab page, and default search engine. While installed on the device, PUPs also may activate data-tracking functions and spy on users' browsing activities.