So the question is: is minecraft using the security manager per default. it will not write into directories you don't allow it too. Once you turn on the security manager (which is an opt-in mechanism) you have the ability to define a set of rules that Java will obey like e.g. The only mechanism that can prevent that and protect the user from the developer in Java, is the security manager. I assume we both use the Java Edition.įirst of all, the Java code, once you run it on a host, can do anything. I have spent a bit of time looking at the binaries of minecraft and the minecraft server spigot.