Security Architecture of the Java Platform (http://www.javaday.bg event - 14.06.2014, Sofia, Bulgaria)

Advanced Java Day
Security Architecture of the
Java Platform
МАРТИН TОШЕВ

Advanced Java Day
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Advanced Java DayAdvanced Java Day
Agenda
• Evolution of the Java security model
• Outside the sandbox - APIs for secure
coding
• Designing and coding with security in mind

Advanced Java Day
Evolution of the Java security
model

Evolution of the
Java security model
• Traditionally - companies protect they
assets using strict physical and network
access policies
• Tools such as anti-virus software, firewalls,
IPS/IDS systems facilitate this approach

Evolution of the
Java security model
• With the introduction of various
technologies for loading and executing
code on the client machine from the
browser (such as Applets) - a new range
of concerns emerge related to client
security – this is when the Java security
sandbox starts to evolve …

Evolution of the
Java security model
• The goal of the Java security sandbox is to
allow untrusted code from applets to be
executed in a trusted environment such as
the user's browser

Evolution of the
Java security model
• JDK 1.0 (when it all started …) – the
original sandbox model was introduced
Applet
(untrusted)
System code
(trusted)
JVM
Browser
http://javaday.bg/demoapplet

Evolution of the
Java security model
• Code executed by the JVM is divided in
two domains – trusted and untrusted
• Strict restriction are applied by default on
the security model of applets such as
denial to read/write data from disk,
connect to the network and so on

Evolution of the
Java security model
• JDK 1.1 (gaining trust …) – applet signing
introduced
Applet
(untrusted)
System code
(trusted)
JVM
Browser
Signed Applet
(trusted)
http://javaday.bg/trustedapplet

Evolution of the
Java security model
• Trusted local code and untrusted
remote code from applets restricted to
a predefined set of operations OR
signed applet code that is trusted

Evolution of the
Java security model
• Steps needed to sign and run an
applet:
– Compile the applet
– Create a JAR file for the applet
– Generate a pair of public/private keys
– Sign the applet JAR with the private key
– Export a certificate for the public key
– Import the Certificate as a Trusted Certificate
– Create the policy file
– Load and run the applet

Evolution of the
Java security model
• JDK 1.2 (gaining more trust …) – fine-
grained access control
Applet
System code
JVM
Browser
grant codeBase http://javaday.bg/demoapplet {
permission java.io.FilePermissions “C:Windows” “delete”
}
security.policy
SecurityManager.checkPermission(…)
AccessController.checkPermission(…)

Evolution of the
Java security model
• Since the security model is code-centric -
additional access control decisions are
specified in a security policy
• No more notion of trusted and untrusted
code

Evolution of the
Java security model
• The notion of protection domain
introduced – determined by the security
policy
• Two types of protection domains – system
and application

Evolution of the
Java security model
• The protection domain is set during
classloading and contains the code
source and the list of permissions for the
class
applet.getClass().getProtectionDomain();

Evolution of the
Java security model
• One permission can imply another
permission
java.io.FilePermissions “C:Windows” “delete”
implies
java.io.FilePermissions “C:Windowssystem32” “delete”

Evolution of the
Java security model
• One code source can imply another code
source
codeBase http://javaday.bg/
implies
codeBase http://javaday.bg/demoapplet

Evolution of the
Java security model
• Since an execution thread may pass through
classes loaded by different classloaders (and
hence – have different protection domains)
the following rule of thumb applies:
The permission set of an execution thread is considered
to be the intersection of the permissions of all protection
domains traversed by the execution thread

Evolution of the
Java security model
• JDK 1.3, 1,4 (what about entities running
the code … ?) – JAAS
Applet
System code
JVM
Browser
grant principal javax.security.auth.x500.X500Principal "cn=Tom"
{ permission java.io.FilePermissions “C:Windows” “delete” }
security.policy

Evolution of the
Java security model
• JAAS (Java Authentication and
Authorization Service) extends the security
model with role-based permissions
• The protection domain of a class now may
contain not only the code source and the
permissions but a list of principals

Evolution of the
Java security model
• The authentication component of JAAS is
independent of the security sandbox in
Java and hence is typically used in more
wider context (such as j2ee app servers)
• The authorization component is the one
that extends the Java security policy

Evolution of the
Java security model
• Core classes of JAAS:
– javax.security.auth.Subject - an authenticated subject
– java.security.Principal - identifying characteristic of a subject
– javax.security.auth.spi.LoginModule - interface for
implementors of login (PAM) modules
– javax.security.auth.login.LoginContext - creates objects used
for authentication

Evolution of the
Java security model
• Up to JDK 1.4 the following is a typical
flow for permission checking:
1) upon system startup a security policy is set and a
security manager is installed
Policy.setPolicy(…)
System.setSecurityManager(…)

Evolution of the
Java security model
2) during classloading (e.g. of a remote applet)
bytecode verification is done and the protection
domain is set for the current classloader (along
with the code source, the set of permissions and
the set of JAAS principals)

Evolution of the
Java security model
3) when system code is invoked from the remote
code the SecurityManager is used to check
against the intersection of protection domains
based on the chain of threads and their call stacks

Evolution of the
Java security model
SocketPermission permission = new
SocketPermission("javaday.bg:8000-
9000","connect,accept");
SecurityManager sm = System.getSecurityManager();
if (sm != null) sm.checkPermission(permission);

Evolution of the
Java security model
4) application code can also do permission checking
against remote code using a SecurityManager or
an AccessController

Evolution of the
Java security model
SocketPermission permission = new
SocketPermission("javaday.bg:8000-9000",
"connect,accept");
AccessController.checkPermission(permission)

Evolution of the
Java security model
5) application code can also do permission checking
with all permissions of the calling domain or a
particular JAAS subject
AccessController.doPrivileged(…)
Subject.doAs(…)
Subject.doAsPrivileged(…)

Evolution of the
Java security model
• The security model defined by
java.lang.SecurityManager is
customizable
• For example: Oracle JVM uses a custom
SecurityManager with additional permission classes
where the code source is a database schema
(containing e.g. Java stored procedures)

Evolution of the
Java security model
• JDK 1.5, 1.6 (enhancing the model …) –
new additions to the sandbox model (e.g.
LDAP support for JAAS)

Evolution of the
Java security model
• JDK 1.7, 1.8 (further enhancing the model
…) – enhancements to the sandbox model
(e.g. AccessController.doPrivileged() for
checking against a subset of permissions)

Evolution of the
Java security model
• JDK 1.9 and beyond … (applying the
model to modules …)
application module
system
module 1
JVM
Browser
http://javaday.bg/appmodule
security.policy
system
module 2

Evolution of the
Java security model
• By modules we understand modules in
JDK as defined by project Jigsaw
• Modules must conform to the same security
model as applets – moreover each module is
loaded by a different classloader – hence
classes in different modules must have
different protection domains

Evolution of the
Java security model
• Modularization of the JDK system classes
allows further to define fine-grained
access control permissions for classes in
the system domain
• This is not currently allowed due to the
monolithic nature of the JDK

Advanced Java Day
Outside the sandbox - APIs for
secure coding

secure coding
• The security sandbox defines a strict
model for execution of remote code in the
JVM
• The other side of the coin are the security
APIs that provide utilities for implementing
the different aspects of application security
…

secure coding
• The additional set of APIs includes:
– JCA (Java Cryptography Architecture)
– PKI (Public Key Infrastructure) utilities
– JSSE (Java Secure Socket Extension)
– Java GSS API (Java Generic Security Services)
– Java SASL API (Java Simple Authentication and
Security Layer)

secure coding
• JCA provides utilities for:
– creating digital signatures
– creating message digests
– using cryptographic ciphers (symetric/asymetric,
block/stream)
– using different other types of cryptographic services
and algorithms

secure coding
• JCA has a pluggable architecture
• JCA is independent from particular
cryptographic algorithms
• JCA continues to evolve (especially by
providing stronger cryptographic algorithms)

secure coding
• PKI utilities provide means for working
with:
– certificates
– certificate revocation lists (CRL)
– OCSP (Online Certificate Status Protocol)
– key stores and trust stores (also based on the PKCS -
public-key cryptography standards)

secure coding
• PKI certificate revocation check (revision):
• PKI utilities continue to evolve (especially in
providing more support for managing
certificates and keys)
certificate
authorityrevocation
checking
OCSP
CRL
certificate
certificate

secure coding
• JSSE provides an implementation of the
TSL/SSL sockets for working with remote
communication
• JSSE continues to evolve (especially in
the support for additional features such as
Server Name Identication)

secure coding
• Java GSS API provides an alternative of
JSSE for secure communication
• Java GSS API is a framework for providing
token-based security services that is
independent of the underlying protocols

secure coding
• Java GSS API can be used along with
JAAS for authentication purposes
• Java GSS API continues to evolve
(especially in the support for Kerberos
authentication)

secure coding
• Java SASL defines a protocol for
exchange of authentication data
• Java SASL is a framework where external
providers give concrete semantics to the
authentication data being exchanged

secure coding
• Java SASL continues to evolve (especially
with support for additional and enhanced
properties for exchanging authentication
data)

Advanced Java Day
Designing and coding with
security in mind

Designing and coding
with security in mind
• First of all - follow programing guidelines
and best practices - most are not bound to
the Java programming language (input
validation, error handling, type safety,
access modifiers, resource cleanup,
prepared SQL queries and whatever you
can think of …)

• Respect the SecurityManager -
designlibraries so that they work in
environments with installed
SecurityManager
• Example: GSON library does not respect the
SecurityManager and cannot be used without additional
reflective permissions in some scenarios

• Grant minimal permissions to code that
requires them - the principle of "least
privilege"
• Copy-pasting, of course, increases the risk
of security flows (if the copied code is
flawed)

• Sanitize exception messages from
sensitive information - often this results in
an unintended exposal of exploitable
information
• Let alone exception stacktraces … in many
cases they convey a wealth of information about
the system

References
• Java Security Overview (white paper)
http://www.oracle.com/technetwork/java/js-white-paper-
149932.pdf
• Java SE Platform Security Architecture Spec
http://docs.oracle.com/javase/7/docs/technotes/guides/sec
urity/spec/security-spec.doc.html
• Inside Java 2 Platform Security, 2nd edition
http://www.amazon.com/Inside-Java%C2%BF-Platform-
Security-Implementation/dp/0201787911

References
• Java Security, 2nd edition, Scott Oaks
http://shop.oreilly.com/product/9780596001575.do
• Securing Java, Gary McGraw, Ed Felden
http://www.securingjava.com
• Secure Coding Guidelines for Java SE
http://www.oracle.com/technetwork/java/seccodeguide
-139067.html#0

References
• Java 2 Network Security
http://www.amazon.com/JAVA-Network-Security-2nd-
Edition/dp/0130155926
• Java Security Documentation
http://docs.oracle.com/javase/8/docs/technotes/guides/
security/index.html

References
• Core Java Security: Class Loaders, Security
Managers and Encryption
http://www.informit.com/articles/article.aspx?p=118796
7
• Overview of Java Security Models
http://docs.oracle.com/cd/E12839_01/core.1111/e1004
3/introjps.htm#CHDCEJGH

Security Architecture of the Java Platform (http://www.javaday.bg event - 14.06.2014, Sofia, Bulgaria)

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