A possible security vulnerability has been identified in Apache Kafka Connect API.
This requires access to a Kafka Connect worker, and the ability to create/modify connectors on it with an arbitrary Kafka client SASL JAAS config
and a SASL-based security protocol, which has been possible on Kafka Connect clusters since Apache Kafka Connect 2.3.0.
When configuring the connector via the Kafka Connect REST API, an authenticated operator can set the sasl.jaas.config
property for any of the connectors Kafka clients to com.sun.security.auth.module.JndiLoginModule, which can be done via the
producer.override.sasl.jaas.config, consumer.override.sasl.jaas.config, or admin.override.sasl.jaas.config properties.
This will allow the server to connect to the attackers LDAP server
and deserialize the LDAP response, which the attacker can use to execute java deserialization gadget chains on the Kafka connect server.
Attacker can cause unrestricted deserialization of untrusted data (or) RCE vulnerability when there are gadgets in the classpath.
Since Apache Kafka 3.0.0, users are allowed to specify these properties in connector configurations for Kafka Connect clusters running with out-of-the-box configurations. Before Apache Kafka 3.0.0, users may not specify these properties unless the Kafka Connect cluster has been reconfigured with a connector client override policy that permits them.
Since Apache Kafka 3.4.0, we have added a system property (-Dorg.apache.kafka.disallowed.login.modules) to disable the problematic login modules usage in SASL JAAS configuration. Also by default com.sun.security.auth.module.JndiLoginModule is disabled in Apache Kafka Connect 3.4.0.
We advise the Kafka Connect users to validate connector configurations and only allow trusted JNDI configurations. Also examine connector dependencies for vulnerable versions and either upgrade their connectors, upgrading that specific dependency, or removing the connectors as options for remediation. Finally, in addition to leveraging the org.apache.kafka.disallowed.login.modules system property, Kafka Connect users can also implement their own connector client config override policy, which can be used to control which Kafka client properties can be overridden directly in a connector config and which cannot.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Kafka_connect | Apache | 2.3.0 (including) | 3.3.2 (including) |
| Kafka | Ubuntu | upstream | * |
| Red Hat AMQ Streams 2.2.1 | RedHat | * | |
| Red Hat AMQ Streams 2.4.0 | RedHat | * |
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.