A vulnerability has been identified in Apache Kafka Clients, which may allow attackers to gain unauthorized access to files and directories, as well as exploit improper privilege management. This blog post explores the details of this vulnerability (CVE-2024-31141), provides code snippets demonstrating the attack, links to original references, and guidance on how to mitigate the risk.

Vulnerability Details

Apache Kafka Clients are widely used for managing and processing streaming data through distributed systems. They can be customized with configuration data, which is provided using ConfigProvider plugins. Apache Kafka includes several implementations of ConfigProviders, such as FileConfigProvider, DirectoryConfigProvider, and EnvVarConfigProvider. These implementations allow reading configuration data from disk or environment variables.

In certain situations, untrusted parties may be allowed to specify Apache Kafka Clients configurations. Attackers can exploit these ConfigProviders to read arbitrary contents of the disk and access environment variables, potentially gaining unauthorized access to sensitive information.

This vulnerability, identified as CVE-2024-31141, is particularly relevant to Apache Kafka Connect. In this context, an attacker can escalate from REST API access to filesystem and environment access, which may pose significant security risks, especially for SaaS products and other environments. The issue affects Apache Kafka Clients versions 2.3. through 3.5.2, 3.6.2, and 3.7..

Exploit Example

Consider an application that uses Apache Kafka Connect and allows users to provide their own configuration data. An attacker may manipulate the Connect worker configuration to include a malicious ConfigProvider that reads sensitive data from the disk or environment variables.

// Example of an attacker using FileConfigProvider to read arbitrary files
Map<String, String> workerConfig = new HashMap<>();
workerConfig.put("config.providers", "file");
workerConfig.put("config.providers.file.class", "org.apache.kafka.common.config.provider.FileConfigProvider");
workerConfig.put("config.providers.file.param.sensitive.file", "/etc/passwd");

Mitigation Recommendations

Users with affected applications should upgrade their kafka-clients to version 3.8. or newer, and set the JVM system property org.apache.kafka.automatic.config.providers=none.

For users of Kafka Connect with one of the listed ConfigProvider implementations in their worker configuration, adding appropriate allowlist.pattern and allowed.paths settings is recommended to restrict the operation to appropriate bounds.

# Example of restricting FileConfigProvider operations to a safe directory
config.providers=file
config.providers.file.class=org.apache.kafka.common.config.provider.FileConfigProvider
config.providers.file.allowed.paths=/home/user/safe-directory

For environments that trust users with disk and environment variable access, setting the system property is not recommended for users of Kafka Clients or Kafka Connect. Similarly, setting the system property is not advised for users of Kafka Broker, Kafka MirrorMaker 2., Kafka Streams, and Kafka command-line tools.

Additional Resources

- Original Apache Kafka advisory
- Apache Kafka Clients upgrade guide
- Kafka Connect documentation

Conclusion

CVE-2024-31141 demonstrates the risk associated with improper privilege management and unauthorized access to files and directories in Apache Kafka Clients. By understanding the vulnerability, its potential exploit scenarios, and recommended mitigation strategies, users can better protect their applications and environments against such attacks. Upgrading to the latest version of Kafka Clients and properly configuring the system properties are crucial steps to minimize security risks.

Timeline

Published on: 11/19/2024 09:15:03 UTC
Last modified on: 11/19/2024 21:57:32 UTC