There are several novelties that will be introduced by Android O but the new version of the green robot will also have the task of closing down some security flaws in the system. One of the most important is related to the SYSTEM_ALERT_WINDOW permission that allows applications to show content over to other windows and is triggered by default.
Reported by the Check Point security company, which claims that 64% of Android ransomware and 57% of adware-containing apps were used. Although Google has implemented many security measures that can prevent most malicious abuse, it seems that developers have found ways to circumvent security controls.
For this reason, Android O introduces the TYPE_APPLICATION_OVERLAY permission that will avoid overlay on system critical windows. This should drastically reduce the number of ransomware and adware that sometimes exploited the accidental permission of permissions too high.