Kafka Connect Deserialization via SASL JAAS Config (v2.3.0-3.4.0)
CVE-2023-25194 Published on February 7, 2023
Apache Kafka Connect API: Possible RCE/Denial of service attack via SASL JAAS JndiLoginModule configuration using Kafka Connect
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 connector's 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 attacker's 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.
Vulnerability Analysis
CVE-2023-25194 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2023-25194. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2023-25194 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2023-25194
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Affected Versions
Apache Software Foundation Apache Kafka Connect API:- Version 2.3.0 and below 3.4.0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.