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Date: Tue, 7 Feb 2023 23:41:30 +0530
From: Manikumar <>
Subject: CVE-2023-25194: Apache Kafka: Possible RCE/Denial of service attack
 via SASL JAAS JndiLoginModule configuration using Kafka Connect

Severity: important


A possible security vulnerability has been identified in Apache Kafka
Connect. 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
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
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. Attackers 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 "" is disabled
in Apache Kafka 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.


Apache Kafka would like to thank Jari Jääskelä
and 4ra1n and Y4tacker (they found vulnerabilities in other Apache projects.
After discussion between PMC of the two projects, it was finally
confirmed that it was the vulnerability of Kafka then they reported it to us)


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