Madware

Madware, or 'mobile adware', is unusually persistent and aggressive adware that affects mobile devices. As well as being annoying, madware can also enact data and identity theft, and messaging fraud. Madware is known to generate unwanted pop-up ads, text messages, alerts and icons, and also change web browser settings and ringtones. Madware can insert ads all over the device - including within calendars, photo albums, and other places where users store their personal data.
As madware is a fairly new type of cyber threat, a victim may not always recognize it for what it is - they may assume that it is a malfunction within their mobile device.
It's difficult to remove madware from a mobile device - the best option is to prevent it being installed in the first place, by using a mobile antivirus. It's also important to keep a close eye on what apps you are using, what may be running in the background, and what automated Settings you may have - for example, don't let your mobile device auto-connect to public Wi-Fi networks, as these are great entry points for malwares.