Apache Brooklyn uses the SnakeYAML library for parsing YAML inputs. SnakeYAML allows the use of YAML tags to indicate that SnakeYAML should unmarshal data to a Java type. In the default configuration in Brooklyn before 0.10.0, SnakeYAML will allow unmarshalling to any Java type available on the classpath. This could provide an authenticated user with a means to cause the JVM running Brooklyn to load and run Java code without detection by Brooklyn. Such code would have the privileges of the Java process running Brooklyn, including the ability to open files and network connections, and execute system commands. There is known to be a proof-of-concept exploit using this vulnerability.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Brooklyn | Apache | * | 0.9.0 (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.