CWE-594: J2EE Framework: Saving Unserializable Objects to Disk

Description

When the J2EE container attempts to write unserializable objects to disk there is no guarantee that the process will complete successfully.

In heavy load conditions, most J2EE application frameworks flush objects to disk to manage memory requirements of incoming requests. For example, session scoped objects, and even application scoped objects, are written to disk when required. While these application frameworks do the real work of writing objects to disk, they do not enforce that those objects be serializable, thus leaving the web application vulnerable to crashes induced by serialization failure. An attacker may be able to mount a denial of service attack by sending enough requests to the server to force the web application to save objects to disk.

Potential Impact

Integrity

Modify Application Data

Availability

DoS: Crash, Exit, or Restart

Demonstrative Examples

In the following Java example, a Customer Entity JavaBean provides access to customer information in a database for a business application. The Customer Entity JavaBean is used as a session scoped object to return customer information to a Session EJB.

Bad

@Entitypublic class Customer {
                     
                        private String id;private String firstName;private String lastName;private Address address;
                           public Customer() {}
                           public Customer(String id, String firstName, String lastName) {...}
                           @Idpublic String getCustomerId() {...}
                           public void setCustomerId(String id) {...}
                           public String getFirstName() {...}
                           public void setFirstName(String firstName) {...}
                           public String getLastName() {...}
                           public void setLastName(String lastName) {...}
                           @OneToOne()public Address getAddress() {...}
                           public void setAddress(Address address) {...}
                     
                     
                     }

However, the Customer Entity JavaBean is an unserialized object which can cause serialization failure and crash the application when the J2EE container attempts to write the object to the system. Session scoped objects must implement the Serializable interface to ensure that the objects serialize properly.

Good

public class Customer implements Serializable {...}

Mitigations & Prevention

Architecture and DesignImplementation

All objects that become part of session and application scope must implement the java.io.Serializable interface to ensure serializability of containing objects.

Taxonomy Mappings

Software Fault Patterns: SFP1 — Glitch in computation

Frequently Asked Questions

What is CWE-594?

CWE-594 (J2EE Framework: Saving Unserializable Objects to Disk) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Variant-level weakness. When the J2EE container attempts to write unserializable objects to disk there is no guarantee that the process will complete successfully.

How can CWE-594 be exploited?

Attackers can exploit CWE-594 (J2EE Framework: Saving Unserializable Objects to Disk) to modify application data. This weakness is typically introduced during the Implementation phase of software development.

How do I prevent CWE-594?

Key mitigations include: All objects that become part of session and application scope must implement the java.io.Serializable interface to ensure serializability of containing objects.

What is the severity of CWE-594?

CWE-594 is classified as a Variant-level weakness (Low-Medium abstraction). Its actual severity depends on the specific context and how the weakness manifests in your application.