Check Point researchers found a shortcoming in the way Android apps use storage resources. Careless use of External Storage by applications may open the door to an attack resulting in any number of undesired outcomes, such as silent installation of unrequested, potentially malicious, apps to the users phone. Failing to employ security precautions on their own leaves applications vulnerable to the risks of malicious data manipulation. The researchers have demonstrated the ability to install an undesired application in the background, causing it to crash and causing it a denial of service.”]
Source: https://blog.checkpoint.com/2018/08/12/man-in-the-disk-a-new-attack-surface-for-android-apps/