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Overridden/hidden method modifier | Overriding/hiding method modifier |
|---|---|
public | public |
protected | protected or public |
default | default or protected or private |
privateanything but private | Cannot be overridden |
This also means that there is potential for some functionality having a restrictive modifier to be overridden by a less restrictive modifier.
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This noncompliant code example exemplifies how a malicious subclass Sub can override the doLogic method of the super class. Any user of Sub will be able to invoke the doLogic method even though since the base class BadScope defined it with the private access protected access modifier. The class Sub can allow more access than BadScope by using the public modifier.
| Code Block | ||
|---|---|---|
| ||
class BadScope {
privatepublic void doLogic() { System.out.println("Super invoked"); }
}
public class Sub extends BadScope {
public void doLogic() {
System.out.println("Sub invoked");
//do restrictive operations
}
}
|
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Do not override a method unless absolutely necessary. Declare all methods and fields final to avoid malicious subclassing. This is in compliance with <xyz rule>the tenets of OBJ31-J. Misusing public static variables and OBJ00-J. Declare data members private.
| Code Block | ||
|---|---|---|
| ||
class BadScope {
private final void doLogic() { System.out.println("Super invoked"); }
}
|
Risk Assessment
Subclassing allows access restrictions to be weakened, possibly compromising the security of a Java application.
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