Severity: Important Vendor: The Apache Software Foundation Versions Affected: * Unsupported Codehaus versions of Groovy from 1.7.0 to 2.4.3 * Apache Groovy 2.4.4 to 2.4.7 * Fixed in version 2.4.8 Impact: Remote execution of untrusted code, DoS Description: When an application with Groovy on classpath uses standard Java serialization mechanisms, e.g. to communicate between servers or to store local data, it is possible for an attacker to bake a special serialized object that will execute code directly when deserialized. All applications which rely on serialization and do not isolate the code which deserializes objects are subject to this vulnerability. This is similar to CVE-2015-3253 but this exploit involves extra wrapping of objects and catching of exceptions which are now safe guarded against. Mitigation: Users of Groovy relying on (de)serialization with the affected versions should apply one of the following mitigations: * Isolate the code doing the (de)serialization * Upgrade to Apache Groovy 2.4.8 or later * Users of older versions of Groovy can apply the following patch to the `MethodClosure` class (`src/main/org/codehaus/groovy/runtime/MethodClosure.java`): ``` public class MethodClosure extends Closure { + private void readObject(java.io.ObjectInputStream stream) throws IOException, ClassNotFoundException { + if (ALLOW_RESOLVE) { + stream.defaultReadObject(); + } + throw new UnsupportedOperationException(); + } ``` Credit: This vulnerability was discovered by: * Sam Thomas of Pentest Limited working with Trend Micro's Zero Day Initiative History: * 2016-09-20 Original advisory * 2017-01-12 Updated information on affected versions References: * http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-6814 * http://groovy-lang.org/security.html