Apache Dubbo is a java based, open source RPC framework. Versions prior to 2.6.10 and 2.7.10 are vulnerable to pre-auth remote code execution via arbitrary bean manipulation in the Telnet handler. The Dubbo main service port can be used to access a Telnet Handler which offers some basic methods to collect information about the providers and methods exposed by the service and it can even allow to shutdown the service. This endpoint is unprotected. Additionally, a provider method can be invoked using the invoke handler. This handler uses a safe version of FastJson to process the call arguments. However, the resulting list is later processed with PojoUtils.realize which can be used to instantiate arbitrary classes and invoke its setters. Even though FastJson is properly protected with a default blocklist, PojoUtils.realize is not, and an attacker can leverage that to achieve remote code execution. Versions 2.6.10 and 2.7.10 contain fixes for this issue.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Dubbo | Apache | * | 2.6.10 (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.