CVE-2023-21979 Overview
CVE-2023-21979 is a high-severity information disclosure vulnerability affecting the Core component of Oracle WebLogic Server, a widely deployed enterprise application server within Oracle Fusion Middleware. The vulnerability allows an unauthenticated attacker with network access via the T3 protocol to gain unauthorized access to critical data or complete access to all Oracle WebLogic Server accessible data.
This vulnerability is particularly concerning for enterprise environments as WebLogic Server is commonly deployed in mission-critical business applications, and the T3 protocol is the native communication protocol used by WebLogic for client-server communication.
Critical Impact
Unauthenticated remote attackers can exploit this vulnerability via the T3 protocol to access sensitive data stored on or accessible by the WebLogic Server, potentially exposing confidential business information, credentials, and application data.
Affected Products
- Oracle WebLogic Server 12.2.1.3.0
- Oracle WebLogic Server 12.2.1.4.0
- Oracle WebLogic Server 14.1.1.0.0
Discovery Timeline
- 2023-04-18 - CVE-2023-21979 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-21979
Vulnerability Analysis
This vulnerability resides in the Core component of Oracle WebLogic Server and is classified under CWE-306 (Missing Authentication for Critical Function). The flaw enables unauthenticated attackers to exploit the T3 protocol to access sensitive data without requiring any privileges or user interaction. The vulnerability has significant confidentiality impact, allowing attackers to potentially access all data accessible by the WebLogic Server instance.
The T3 protocol is Oracle's proprietary protocol used for communication between WebLogic Server instances and clients. It handles serialization and deserialization of Java objects, making it a frequent target for security researchers and attackers alike.
Root Cause
The vulnerability stems from missing authentication controls for critical functions within the WebLogic Server Core component. This authentication gap allows remote attackers to interact with sensitive server functionality via the T3 protocol without providing valid credentials. The lack of proper access controls on certain T3 protocol handlers exposes internal server data to unauthorized parties.
Attack Vector
The attack is network-based and requires no authentication, privileges, or user interaction. An attacker can exploit this vulnerability by:
- Identifying a WebLogic Server instance with T3 protocol exposed (typically on port 7001 or 7002)
- Crafting malicious T3 protocol requests that bypass authentication checks
- Extracting sensitive data from the server response
The vulnerability is considered easily exploitable, meaning attackers with basic technical knowledge and network access to the T3 service can successfully compromise affected systems.
The attack leverages weaknesses in the T3 protocol handler within the WebLogic Server Core component. Attackers can send specially crafted T3 requests to extract sensitive information from the server without authentication. For detailed technical information, refer to the Oracle Critical Patch Update April 2023.
Detection Methods for CVE-2023-21979
Indicators of Compromise
- Unusual or unauthorized T3 protocol connections to WebLogic Server ports (7001, 7002)
- Anomalous outbound data transfers from WebLogic Server instances
- Unexpected T3 protocol requests from external IP addresses
- Log entries indicating failed or suspicious authentication attempts on the T3 protocol
Detection Strategies
- Implement network monitoring to detect T3 protocol traffic from untrusted sources
- Configure WebLogic Server audit logging to capture T3 protocol connection attempts
- Deploy intrusion detection systems (IDS) with signatures for WebLogic T3 protocol exploitation patterns
- Monitor for reconnaissance activity targeting WebLogic Server ports
Monitoring Recommendations
- Enable comprehensive audit logging in WebLogic Server for all T3 protocol connections
- Monitor network traffic for connections to T3 ports from external or untrusted networks
- Implement SIEM rules to alert on unusual T3 protocol activity patterns
- Regularly review WebLogic Server access logs for unauthorized data access attempts
How to Mitigate CVE-2023-21979
Immediate Actions Required
- Apply the Oracle Critical Patch Update from April 2023 immediately
- Restrict T3 protocol access using network-level controls (firewalls, security groups)
- Disable T3 protocol if not required for business operations
- Implement network segmentation to isolate WebLogic Server instances from untrusted networks
Patch Information
Oracle has addressed this vulnerability in the April 2023 Critical Patch Update. Administrators should apply the appropriate patch for their WebLogic Server version (12.2.1.3.0, 12.2.1.4.0, or 14.1.1.0.0) as soon as possible. The patch can be obtained from the Oracle Critical Patch Update April 2023.
Workarounds
- Restrict T3 protocol access to trusted networks and clients only using connection filters
- Implement network-level access controls to block T3 protocol traffic from untrusted sources
- Consider using HTTPS/SSL tunneling for WebLogic communication instead of raw T3 protocol
- Deploy a Web Application Firewall (WAF) in front of WebLogic Server instances
# WebLogic Server Connection Filter Configuration
# Add to config.xml to restrict T3 access to trusted networks only
# Example: Configure connection filter rules in WebLogic Console
# Navigate to: Domain > Security > Filter
# Add filter rules to allow T3 only from trusted IP ranges:
# Rule: * * 7001 deny t3 t3s
# Rule: 10.0.0.0/8 * 7001 allow t3 t3s
# Rule: 192.168.1.0/24 * 7001 allow t3 t3s
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
