CVE-2016-6814: Deserialization of Untrusted Data in Groovy

Background

Groovy is a powerful, dynamic language for the Java Virtual Machine (JVM) that offers a concise and expressive syntax. It is widely used for scripting, testing, and building applications on the JVM. The vulnerability (CVE-2016-6814) affects unsupported Codehaus versions of Groovy from 1.7.0 to 2.4.3 and Apache Groovy 2.4.4 to 2.4.7. When an application with these versions uses standard Java serialization mechanisms, it becomes susceptible to deserialization attacks. An attacker can craft a specially serialized object that executes code directly upon deserialization. This vulnerability poses a significant risk to applications that rely on serialization and do not isolate the code responsible for deserializing objects.

Vulnerability Detail

The vulnerability arises due to a lack of proper input validation during deserialization. By exploiting this flaw, an attacker can execute arbitrary code on the target system. This can lead to remote code execution, privilege escalation, and unauthorized access to sensitive data. The severity of this vulnerability is rated as CRITICAL with a CVSS score of 9.8. The Common Weakness Enumeration (CWE) ID associated with this vulnerability is CWE-502.

Workaround

A possible workaround for this vulnerability is to disable or limit the usage of Java serialization in the affected application. This can be achieved by implementing alternative serialization mechanisms or by using serialization libraries that provide additional security features, such as input validation and secure deserialization. Here is an example of how to disable Java serialization in a Java application:

import java.io.ObjectInputStream;

public class SecureObjectInputStream extends ObjectInputStream {

    public SecureObjectInputStream(InputStream in) throws IOException {
        super(in);
    }

    @Override
    protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
        throw new InvalidClassException("Unauthorized deserialization attempt", desc.getName());
    }

}

By implementing a custom SecureObjectInputStream class and overriding the resolveClass method, the deserialization process can be controlled and unauthorized deserialization attempts can be blocked.

Conclusion

The deserialization vulnerability in Groovy (CVE-2016-6814) poses a significant risk to applications that rely on serialization and do not properly validate input during deserialization. Upgrading to a supported version of Groovy and implementing secure deserialization practices are crucial to mitigate this vulnerability. For further assistance and support in vulnerability remediation, please contact DevNack.com.

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