The Java implementation of AMF3 deserializers used in Flamingo amf-serializer by Exadel, version 2.2.0, may allow instantiation of arbitrary classes via their public parameter-less constructor and subsequently call arbitrary Java Beans setter methods. The ability to exploit this vulnerability depends on the availability of classes in the class path that make use of deserialization. A remote attacker with the ability to spoof or control information may be able to send serialized Java objects with pre-set properties that result in arbitrary code execution when deserialized.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Flamingo | Exadel | 2.2.0 (including) | 2.2.0 (including) |
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.