Unsafe Mobile Code

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Abstract

The program violates secure coding principles for mobile code by returning a private array variable from a public access method.

Description

Returning a private array variable from a public access method allows the calling code to modify the contents of the array, effectively giving the array public access and contradicting the intentions of the programmer who made it private.

Examples

The following Java Applet code mistakenly returns a private array variable from a public access method.

	public final class urlTool extends Applet {
		private URL[] urls;
		public URL[] getURLs() {
			return urls;
		}
			...
	}

Mobile code, in this case a Java Applet, is code that is transmitted across a network and executed on a remote machine. Because mobile code developers have little if any control of the environment in which their code will execute, special security concerns become relevant. One of the biggest environmental threats results from the risk that the mobile code will run side-by-side with other, potentially malicious, mobile code. Because all of the popular web browsers execute code from multiple sources together in the same JVM, many of the security guidelines for mobile code are focused on preventing manipulation of your objects' state and behavior by adversaries who have access to the same virtual machine where your program is running.

Related Principles

Use encapsulation