Java Security

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Java Security

• Susan Kovacs

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Topics of Discussion

• Why is security an issue?
• Types of security breaches
• Javas approach
• the Language
• the Libraries
• Browsers
• Conclusion

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Why is security an issue?
What is an applet?
A Java program that is run from inside a web
browser. The html page loaded into the web
browser contains an ltappletgt tag, which tells the
browser where to find the Java .class files. For
example,
appletviewer http//foo.com/jo/coolApplet.html
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Why is security an issue?
The class files for an applet are automatically
downloaded when a user goes to the containing Web
page in a browser. It is therefore likely that a
user will encounter applets from untrusted
sources. Without any security, this would be a
convenient way to spread viruses.
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Types of breaches

• Integrity Attacks
• Availability Attacks
• Disclosure Attacks
• Annoyance Attacks

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Types of breaches

• Integrity Attacks
• Deletion / modification of files
• Modification of memory currently in use
• Killing processes / threads

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Types of breaches

• Availability Attacks
• Allocating large amounts of memory
• Creating thousands of windows
• Creating high priority process / threads

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Types of breaches

• Disclosure Attacks
• Mailing information about your machine
• /etc/passwd
• Sending personal or company files to an adversary
  or competitor over the network

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Types of breaches

• Annoyance Attacks
• Displaying obscene pictures on your screen
• Playing unwanted sounds over your computer

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Javas Approach ...

• The Language
• The Libraries
• Browsers

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The Language

• Access control

• Type-safe

• Absence of pointers

• Garbage collection

• Packages

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The Language

• Access control

• public
• private
• final

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The Language

• Type-safe

The compile time type and runtime type of
variables are guaranteed to be compatible. Prevent
s the forging of access to objects to get around
access control.
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The Language

• Absence of pointers

Pointers cannot be directly manipulated by user
code. Prevents both malicious and accidental
misuse of pointers.
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The Language

• Garbage collection

Manual deallocation provides a round-about way of
illegally casting. Java uses garbage collection
to recover unused memory instead of relying on
explicit user deallocation.
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The Language

• Packages

Provides namespace encapsulation. Prevents
downloaded code from shadowing system library
code with malicious code.
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The Libraries

• Security Manager

• Class Loader

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The Libraries

• Security Manager

Contains methods which are intended to be called
to check specific types of actions. It is
intended to be subclassed and used to instantiate
the desired security policy.
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The Libraries

• Security Manager

Example Public boolean mkdir(String path) throws
IOException SecurityManager security
System.getSecurityManager() if (security !
null) security.checkWrite(path) return
mkdir0()
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The Libraries

• Class Loader

Class loaders are responsible for importing
binary data that defines the running programs
classes and interfaces. Two type primordial
object
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The Libraries

• Class Loader

Due to JVMs approach to loading classes, classes
can by default only see other classes that were
loaded by the same class loader. This allows for
multiple name-spaces inside a single Java
application
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Browsers

• The Web browser defines and implements a security
  policy for running downloaded Java code.
• A Java enabled web browser includes
• Java interpreter and runtime libraries
• classes to implement a Security Manager
• various Class Loaders

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Examples
import java.awt. import java.io. import
java.lang. import java.applet. public
class exitTest extends Applet public void
paint(Graphics g) try
Runtime.getRuntime().exit(-1) catch
(SecurityException e)
g.drawString("Caught security exception trying to
quit", 10, 10)
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Examples
Conclusion An applet can't kill the browser
that loaded it, unless you load the applet from a
directory on your CLASSPATH.
For further examples please visit http//java.sun.
com/sfaq/examples
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Conclusion
In order for a program to be useful, it needs to
access certain resources. Therefore, the key is
not to deny all access but rather to provide
secured access in a controlled environment. Though
Java is not yet perfected, its features and
properties have allowed for a good balance of
power and security.
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Questions ...
THANK YOU!
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References

• Flanagan, David. Java in a Nutshell. 2nd Ed.
  OReilly, California, 1997
• Bank, Joseph. Java Security. http//swissnet.ai.m
  it.edu/jbank/javapaper/javapaper.html. 11 March
  2004
• Venners, Bill. Security and the class loader
  architecutre. http//www.javaworld.com/javaworld/j
  w-09-1997/jw-09-hood_p.html. 27 March 2004
• Applet Security. http//java.sun.com/sfaq. 27
  March 2004.