CVE-2023-46674: Elastic Elasticsearch Privilege Escalation

CVE-2023-46674 Overview

CVE-2023-46674 is an insecure deserialization vulnerability affecting Elastic Elasticsearch Hadoop. The vulnerability allows authenticated users to manipulate Hadoop or Spark configuration properties to trigger unsafe deserialization of Java objects. This type of vulnerability (CWE-502) can enable attackers with local access and low privileges to achieve significant impact on the affected system's confidentiality, integrity, and availability.

Critical Impact

Authenticated users can exploit unsafe Java object deserialization through manipulated Hadoop or Spark configuration properties, potentially leading to local code execution and complete system compromise.

Affected Products

• Elastic Elasticsearch Hadoop versions prior to 7.17.11
• Elastic Elasticsearch Hadoop versions prior to 8.9.0

Discovery Timeline

• Discovered by - Yakov Shafranovich, with Amazon Web Services
• 2023-12-05 - CVE CVE-2023-46674 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-46674

Vulnerability Analysis

This vulnerability stems from insecure deserialization of Java objects within the Elasticsearch Hadoop connector. When processing Hadoop or Spark configuration properties, the application fails to properly validate and sanitize serialized Java objects before deserialization. An authenticated user who can modify these configuration properties can inject malicious serialized objects that, when deserialized, execute arbitrary code in the context of the application.

Java deserialization vulnerabilities are particularly dangerous because they can allow attackers to instantiate arbitrary objects and invoke methods during the deserialization process. The attack requires local access and low privileges, but does not require user interaction, making it exploitable by any authenticated user with access to modify configuration properties.

Root Cause

The root cause is insufficient validation of serialized Java objects from Hadoop or Spark configuration properties. The Elasticsearch Hadoop connector deserializes configuration data without proper type checking or allowlist filtering of acceptable classes. This allows an attacker to craft malicious serialized objects using known gadget chains that execute arbitrary code when deserialized.

Attack Vector

The attack vector is local, requiring authenticated access to the system. An attacker must be able to modify Hadoop or Spark configuration properties that are subsequently processed by the vulnerable Elasticsearch Hadoop connector. The exploitation flow involves:

1. An authenticated user gains access to modify Hadoop/Spark configuration properties
2. The attacker injects a malicious serialized Java object into a configuration property
3. When the Elasticsearch Hadoop connector processes the configuration, it deserializes the malicious object
4. The deserialization process triggers execution of attacker-controlled code

The vulnerability manifests during configuration processing in the Elasticsearch Hadoop connector. Attackers can leverage common Java deserialization gadget chains to achieve code execution. For technical details and specific affected code paths, refer to the Elastic Security Update ESA-2023-28.

Detection Methods for CVE-2023-46674

Indicators of Compromise

• Unusual or unexpected serialized Java objects appearing in Hadoop or Spark configuration properties
• Suspicious process spawning from Elasticsearch Hadoop connector processes
• Anomalous configuration changes made by authenticated users
• Evidence of known Java deserialization gadget chains in configuration data

Detection Strategies

• Monitor for modifications to Hadoop and Spark configuration files and properties by authenticated users
• Implement file integrity monitoring on configuration directories
• Deploy application-level logging to capture deserialization events and configuration processing
• Use runtime application self-protection (RASP) solutions to detect deserialization attacks

Monitoring Recommendations

• Enable detailed audit logging for configuration changes in Hadoop and Spark environments
• Monitor process creation events originating from Elasticsearch Hadoop connector components
• Alert on unexpected network connections or file system access from Elasticsearch processes
• Review authentication logs for unusual access patterns to configuration management interfaces

How to Mitigate CVE-2023-46674

Immediate Actions Required

• Upgrade Elasticsearch Hadoop to version 7.17.11 or later for the 7.x branch
• Upgrade Elasticsearch Hadoop to version 8.9.0 or later for the 8.x branch
• Review and restrict access to users who can modify Hadoop and Spark configuration properties
• Audit recent configuration changes for any suspicious serialized data

Patch Information

Elastic has released security updates to address this vulnerability. Users should upgrade to Elasticsearch Hadoop version 7.17.11 or 8.9.0 or later, depending on their deployment branch. The security advisory is available at Elastic Security Update ESA-2023-28.

Workarounds

• Implement strict access controls to limit which users can modify Hadoop and Spark configuration properties
• Use network segmentation to isolate Elasticsearch Hadoop components from untrusted users
• Deploy application allowlisting to prevent execution of unauthorized code
• Consider implementing Java deserialization filters if available in your JVM version

# Verify Elasticsearch Hadoop version to confirm patched version is installed
# Check for 7.17.11+ or 8.9.0+ versions
hadoop classpath | grep elasticsearch-hadoop

# Review configuration directory permissions
ls -la /etc/hadoop/conf/
ls -la /etc/spark/conf/

# Restrict configuration file permissions to authorized users only
chmod 640 /etc/hadoop/conf/*.xml
chmod 640 /etc/spark/conf/*.conf