CVE-2023-46671: Elastic Kibana Information Disclosure Flaw

CVE-2023-46671 Overview

An information disclosure vulnerability was discovered in Elastic Kibana that may result in sensitive information being recorded in Kibana logs during error conditions. When an error is returned from an Elasticsearch cluster under specific circumstances involving user interaction and an unhealthy cluster state (such as circuit breaker or no shard exceptions), the error message logged may inadvertently contain sensitive credentials including account credentials for the kibana_system user, API Keys, and credentials of Kibana end-users.

Critical Impact

Sensitive credentials including the kibana_system user account, API Keys, and end-user credentials may be exposed in Kibana log files, potentially enabling unauthorized access to the Elasticsearch cluster and associated data.

Affected Products

• Elastic Kibana versions prior to 8.11.1
• Elastic Kibana versions prior to 7.17.15

Discovery Timeline

• 2023-12-13 - CVE CVE-2023-46671 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-46671

Vulnerability Analysis

This vulnerability falls under CWE-532 (Insertion of Sensitive Information into Log File). The issue arises from improper handling of error responses in Kibana when communicating with an Elasticsearch cluster. Under specific error conditions, the application inadvertently logs authentication credentials and API keys that should remain protected.

The vulnerability occurs infrequently and requires a combination of factors: user interaction with the Kibana interface and an unhealthy Elasticsearch cluster state. When these conditions align and Elasticsearch returns certain error types (circuit breaker exceptions or no shard exceptions), the error handling mechanism captures and logs sensitive authentication data that was part of the request context.

The network-accessible nature of the vulnerability means that any authenticated user who can trigger operations that communicate with Elasticsearch could potentially cause sensitive credentials to be logged. While exploitation requires low privileges and no user interaction beyond normal system use, the confidentiality impact is significant as complete credential exposure is possible.

Root Cause

The root cause lies in insufficient sanitization of error messages before they are written to log files. When Kibana encounters specific error responses from Elasticsearch, the error handling routine captures the full request context, which may include authentication headers, API keys, and user credentials. The logging mechanism fails to redact these sensitive values before persisting them to disk.

Attack Vector

The attack vector is network-based and requires an authenticated attacker with low privileges. An attacker with access to Kibana log files could potentially extract credentials logged during error conditions. The attack scenario involves:

1. An authenticated user performing operations that communicate with Elasticsearch
2. The Elasticsearch cluster being in an unhealthy state (returning circuit breaker or shard exceptions)
3. The error condition triggering verbose logging that includes sensitive credentials
4. An attacker with log file access reading the exposed credentials

While direct exploitation is limited to those with log file access, the exposure of kibana_system credentials or API keys could enable subsequent attacks against the Elasticsearch cluster with elevated privileges.

Detection Methods for CVE-2023-46671

Indicators of Compromise

• Presence of authentication tokens, API keys, or user credentials in Kibana log files
• Unusual log entries containing kibana_system account information during error events
• Log entries with credential-like patterns appearing in error message contexts

Detection Strategies

• Implement log scanning tools to detect patterns consistent with exposed credentials (API keys, base64-encoded authentication headers)
• Monitor Kibana logs for error messages containing circuit breaker or no shard exception patterns
• Review access logs for the Kibana log directory to identify unauthorized access attempts
• Deploy file integrity monitoring on Kibana log directories

Monitoring Recommendations

• Configure alerts for Elasticsearch cluster health degradation events that could trigger the vulnerable code path
• Implement centralized log management with credential pattern detection rules
• Monitor for unauthorized access to log file storage locations
• Establish baseline logging patterns to identify anomalous error frequency

How to Mitigate CVE-2023-46671

Immediate Actions Required

• Upgrade Kibana to version 8.11.1 or 7.17.15 (depending on your major version) immediately
• Review existing Kibana log files for any exposed credentials and rotate all potentially compromised credentials
• Restrict access to Kibana log files to only essential personnel
• Rotate the kibana_system user credentials and any API keys that may have been logged

Patch Information

Elastic has released Kibana versions 8.11.1 and 7.17.15 which resolve this vulnerability. Organizations should upgrade to the appropriate patched version based on their deployment:

• For Kibana 8.x deployments: Upgrade to version 8.11.1 or later
• For Kibana 7.x deployments: Upgrade to version 7.17.15 or later

Refer to the Elastic Security Update Discussion (ESA-2023-25) for complete upgrade instructions and additional details.

Workarounds

• Restrict log file permissions to prevent unauthorized access while awaiting patching
• Implement log rotation with secure deletion to minimize exposure window of sensitive data
• Consider temporarily increasing Elasticsearch cluster resources to reduce error frequency
• Configure log shipping to a secure, access-controlled centralized logging system

# Restrict Kibana log file permissions
chmod 600 /var/log/kibana/*.log
chown kibana:kibana /var/log/kibana/*.log

# Configure log rotation with secure deletion
cat >> /etc/logrotate.d/kibana << EOF
/var/log/kibana/*.log {
    daily
    rotate 7
    compress
    delaycompress
    missingok
    notifempty
    create 600 kibana kibana
    shred
}
EOF