Just because you download an app does not mean that it is not vulnerable to exploit or data leaks. The chance of it happening is even higher for those not in traditional app stores.  Additionally, businesses depend on older software applications are at a great risk that security flaws have not been addressed making them vulnerable to breaches. For many of these applications, they patch what is brought to their attention but fail to go back and see if there are other vulnerabilities that need patching. This neglect allows unpatched vulnerabilities to accumulate deep in the software making businesses ripe for exploit by cybercriminals.