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Security in Java2

Explore the evolution of Java security from the original Sandbox model to Java 2's granular control, with insights on security risks, enhancements, and multilayered approaches.

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Security in Java2

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  1. Security in Java2 • Prabhu Ram Raghunathan • Srikanth E. Musti • Deep Kapadia

  2. Is Java still secure?David M. Chess, John F. MorarIBM TJ Watson Research Center • In the beginning there was: • Passive Content • Currently: • Active Content : Macro,ActiveX etc. • Digital Signature used by Office2000, ActiveX • Only macros signed by trusted parties are run.

  3. Original Java Security Model The Sandbox • Security manager – construed guilty. • All programs on N/w assumed Untrusted • Untrusted Applets Prohibited from “damaging the system running them, or reveal private or confidential information”

  4. Thou Shall Not : • Interact with the local file system : read,write,delete or rename files. • Connect to another computer over the network. • Accept network connections from any other computer • Alter System Properties (Environment Variables) • Invoke a program or load a library. • Cause the Java Interpreter to Exit. • Prompt the user without an “Untrusted Applet” warning or Create a new Security Manager.

  5. Effect of Sand Boxing • This set of limits for an applet is the sandbox. • Good: A program can at best display unwanted messages or snoop preferences etc. • Bad : Functionality trimmed. • Escape : JDK 1.1 introduced Command Line feature • Developer signs JAR file digitally. • Users indicate trust in some signers. • a good start toward flexible security in Java • A failure as it was too complex

  6. Keeping up with the Joneses

  7. Enter Java 2 • Uses Java Runtime Environment & Java 2 plugin . • Page has HTML code directing the applet to plugins. • Semi Automatic Install on Demand. • Security Manager on start up reads Policy Files. • Each policy file can describe many principals, and for each principal specify a number of privileges that should be granted applets associated with those principals. A principal can be everyone, a particular signer, a particular place that a program can be loaded from, or a combination of a signer and a place

  8. Morar’s Example • // Everyone can do these things grant { permission java.util.PropertyPermission "user.haircolor"; permission java.io.FilePermission "c:\\temp\\*", "read,write"; }; • // These guys can read and write the directory we set up for them grant signedBy "GoodGuys Inc." { permission java.io.FilePermission "c:\\GoodGuys\\*", "read,write"; };

  9. Morar’s Example • // Things signed by the security administrator and loaded // from his server can do various magic grant signedBy "secadmin", codeBase http://secadmin.example.com/admin/*" { permission java.security.SecurityPermission "Security.insertProvider.*"; permission java.security.SecurityPermission "Security.removeProvider.*"; permission java.security.SecurityPermission "Security.setProperty.*";};

  10. Java 2 Enhancements • No centralized Security Management, but definite steps towards it. • it is possible to configure a system so that both Java 2 plugins and Java applications use the same security manager and security policy. • The Java 2 security system provides more granular control than did previous versions of Java, but the range of available function in the sandbox is essentially the same. Consequently, there is no fundamentally new danger of viral spread in the new environment

  11. Morar’s Final Words • Various Java engines coexisting on a machine could share a common security configuration as in JVM in Netscape, IE, Opera etc. • Risk is very low as possibilities of exploiting holes is limited. • Java2 is Secure.

  12. Securing JavaGary McGraw Edward W. Felten • Security risk categories: * System modification * Invasion of Privacy * Denial of Service * Antagonism • Java presents a multitiered approach to security: * Restricted access to file systems * Restricted access to browser internals * Load time & runtime checks to verify that byte code is following the rules * A system for signing code and assigning it some level of capability

  13. Classes of Security attacks

  14. Parts of default Sandbox

  15. Parts of default Sandbox-The Verifier The Verifier scrutinizes byte code before it is allowed to be run on a local VM.

  16. Parts of default Sandbox-The Verifier(contd.) • Verification * Internal checks * Runtime checks • Verification assures: * The class file has the correct format * Stacks will not be overflowed or underflowed * Byte code instructions all have parameters of the correct type * No illegal data conversions (casts) occur *Private, public, protected, and default accesses are legal * All register accesses and stores are valid

  17. Parts of default Sandbox-The Class Loader • Code is loaded (from the disk or over the network) by a Class Loader. • Class Loaders perform 2 functions: * Finding the byte code. * Class loaders define the namespaces seen by different classes and how those namespaces relate to each other • Class Loaders also need to make sure that important parts of the Java runtime environment are not replaced by impostor code

  18. Parts of default Sandbox-The Class Loader(contd.) • Fake Security Manager – Class Spoofing Spoofing occurs when someone or something pretends to be something it is not. In this figure, an external class has arrived from the Internet and declares itself to be the Security Manager (in order to replace the real Security Manager). If external code were allowed to do this, Java's security system would be trivial to break.

  19. Parts of default Sandbox-The Security Manager • The Security Manager implements a good portion of the entire security model. • How the Security Manager works: The Security Manager keeps tabs on potentially dangerous calls to the native operating system (underlying the VM).

  20. Parts of default Sandbox-The Security Manager(contd.) • The Java library's use of the Security Manager works as follows: * A Java program makes a call to a potentially dangerous operation in the Java API. * The Java API code asks the Security Manager whether the operation should be allowed. * The Security Manager throws a SecurityException back to the Java API if the operation is denied. This exception propagates back to the Java program. * If the operation is permitted, the Security Manager call returns without throwing an exception, and the Java API performs the requested dangerous operation and returns normally.

  21. Capabilities of new security architecture in Java2 • Fine-grained access control. • Configurable security policy. • Extensible access control structure. • Security checks for all Java programs.

  22. New security mechanisms in Sun’s Java2 • Identity • Permissions • Implies • Policy • Protection domains • Access control • And privilege

  23. Malicious Applets Q) What can they do? A) Can attack the local system of a Web surfer causing… • Antagonism • Invasion of Privacy • Denial of Service

  24. Malicious Applets …are known to • Antagonize web surfers • Forge mail from you to whomever the evil applet's author chooses, saying whatever they wish while masquerading as you • Steal your CPU cycles to perform their own work while your legitimate processes languish • Crash your local system by using all available system resources

  25. A simple DOS attack The dreaded thread • Create an applet that starts a thread with its priority set to MAX_PRIORITY. This makes the thread run as quickly as possible and gives it a leg up in the ongoing competition between threads for CPU time. • Redefine the stop() method to null for the thread. • Do something silly in the main part of the applet so that it appears to be harmless. Show a picture or display some cute animation.

  26. A simple DOS attack (cont’d) • Have the thread sleep for a while to delay its malicious activities. Such sleight of hand will have the effect of placing the blame somewhere else when the thread wakes back up to perform its dirty work. • When the thread wakes up, have it begin calculating in an infinite loop (or some other CPU-intensive activity that eats cycles). Such a computation will, in effect, bring the browser down by taking away all available computational resources.

  27. Killing Off the Competition • The Business Assassin Matt LaDue’s Gamelan killer • Stealing Cycles Why have a fast CPU when you can use somebody else’s to do your work for you? • Forge Email (Old dog with new tricks)

  28. Solutions • Disable Java • Know where you are on the Internet • Third party solutions • Improve Java itself • Someone tell Netscape and Microsoft to update their JVM’s

  29. Solutions (cont’d) • Writing safer code • Assess your risks • Understanding Code Signing • Easy to use signing tools • Avoid signing your code as far as possible But try not to throw the good out with the bad

  30. Myths about signing Java code • Signatures denote authorship • If a signer is honest, the code is secure • Signatures imply accountability/liability

  31. The future: Challenges facing Mobile code • New features introduce new security holes • New classes of attacks keep appearing • Secure Distributed Programming • Java as a “secure” true multiuser system

  32. Should we use Java at all

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