Hazelcast IMDG Standard Support has expired. Extended support for version 4.1 ends in April 2024. Extended support for version 4.2 ends in September 2024.

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In Hazelcast Platform, we’ve combined the in-memory storage of IMDG with the stream processing power of Jet. Find out more in our Platform documentation.

The following topics are a good place to start:

Untrusted Deserialization Protection

Hazelcast offers a Java deserialization protection based on whitelisting and blacklisting the class/package names. These listings support prefixes.

This protection is controlled using the configuration element java-serialization-filter under serialization, as shown in the example below.

  • XML

  • YAML

        <java-serialization-filter defaults-disabled="true">
      defaults-disabled: true
          - example.Foo
          - com.acme.app
          - com.hazelcast.
          - java.
          - javax.
          - \[
          - com.acme.app.BeanComparator

As an alternative, you can also configure it programmatically using the JavaSerializationFilterConfig object, as shown in the below example:

Config config = new Config();
JavaSerializationFilterConfig javaSerializationFilterConfig = new JavaSerializationFilterConfig();
Untrusted deserialization protection is not enabled by default. You can enable it simply by setting the element java-serialization-filter or using a non-null JavaSerializationFilterConfig object.

The protection uses a whitelist as the default configuration. When this list is not explicitly provided, the following default prefixes are used for the whitelist:

  • java

  • com.hazelcast.

  • [ (for primitives and arrays)

If you do not want to use the default whitelist prefixes, you must set the defaults-disabled attribute to true.

Once the protection is enabled, the following filtering rules are used when the objects are deserialized:

  • When whitelist is not provided:

    • if the deserialized object’s getClass().getName() is blacklisted or getClass().getPackage().getName() is blacklisted, then deserialization fails

    • deserialization is allowed otherwise.

  • When whitelist is provided:

    • if the deserialized object’s getClass().getName() or getClass().getPackage().getName() is blacklisted, then deserialization fails

    • if the deserialized object’s getClass().getName() or getClass().getPackage().getName() is whitelisted, then deserialization is allowed

    • deserialization fails otherwise.

When deserialization fails, a SecurityException is thrown.

Note that the safest way to provide a protection against untrusted deserialization is using whitelisting (also keep in mind that maintaining such a whitelist can be difficult).