Security manager java stop override
java, securitymanager
Solution
The following website https://www.securecoding.cert.org/confluence/display/jg/20.+Create+a+secure+sandbox+using+a+security+manager says the following about this:
If the current security policy enforced by the current security manager forbids replacements (by omitting the `RuntimePermission("setSecurityManager"))`, any attempt to invoke `setSecurityManager()` will throw a SecurityException.
So it looks like the `checkPermission()` method is the place to check for this.
The Javadoc for `RuntimePermission` has a list of possible values to check for if other critical methods should be catched as well: https://docs.oracle.com/javase/7/docs/api/java/lang/RuntimePermission.html
Problem
If I set a security manager, for example: ``` private static class SecManager extends SecurityManager { ... } ``` With: ``` System.setSecurityManager(new SecManager()); ``` Which permission can I use (or rather prevent), to stop code further down the line setting the security manager again, with elevated permissions. I am looking for a method like: ``` private static class SecManager extends SecurityManager { @Override public void checkSetSecurityManager(SecurityManager manager){ throw new AccessControlException("Not allowed to set new security Manager); } } ``` But of course, the checkSetSecurityManager doesn't exist, so i'm not sure exactly what to look for or how to deny that permission. I would like to use the security manager to allow me to run some untrusted code, but I obviously don't want that code to be able to set it's own security manager. I did consider doing this at the OS level (create a new user for each bit of code), but that seems a little overkill. Instead, I run my own java main, which sets a security manager, then runs the untrusted code within the same JVM. I have made sure their code cannot start new processes already (as this would circumvent the security manager), but I need to make sure they cannot override the existing security manager. I also use checkWrite and checkRead to make sure the code can only read/write in a certain dir. Any help is much appreciated. Thanks,