Apache Dubbo prior to 2.6.9 and 2.7.9 by default supports generic calls to arbitrary methods exposed by provider interfaces. These invocations are handled by the GenericFilter which will find the service and method specified in the first arguments of the invocation and use the Java Reflection API to make the final call. The signature for the $invoke or $invokeAsync methods is Ljava/lang/String;[Ljava/lang/String;[Ljava/lang/Object; where the first argument is the name of the method to invoke, the second one is an array with the parameter types for the method being invoked and the third one is an array with the actual call arguments. In addition, the caller also needs to set an RPC attachment specifying that the call is a generic call and how to decode the arguments. The possible values are: - true - raw.return - nativejava - bean - protobuf-json An attacker can control this RPC attachment and set it to nativejava to force the java deserialization of the byte array located in the third argument.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Dubbo | Apache | 2.5.0 (including) | 2.5.10 (including) |
| Dubbo | Apache | 2.6.0 (including) | 2.6.9 (excluding) |
| Dubbo | Apache | 2.7.0 (including) | 2.7.10 (excluding) |
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.