The only reason this was detected was very overt behavior - opening AD popups. So I guesstimate for each one of these we have 10 that go undetected. This means the whole ecosystem is broken, as there is no reason this will happen only for updates and not for new apps as well. Apple's ecosystem is somewhat better, but I can't imagine they go through every line of code in each package, so most of their review is probably done with some combination of automatic static and dynamic analysis, and these can be fooled. The problem with both platforms is that they don't provide run of the mill users the option of installing an effective firewall and security solutions.