DNS Setting in 3G / 4G / WiFi may be hacked

Your data connection be it via WiFi or mobile may be compromised if the DNS setting is hacked.

Source: New Android Malware Hijacks Router DNS from Smartphone

If you are connecting to dubious WiFi or mobile data or even tethering, use a VPN application.

If you are suspicious of DNS hijacking, go to ipleak.net  to test your current DNS setting.

Check out wiki DNS Hijacking