CVE-2023-21931 Overview
CVE-2023-21931 is a critical information disclosure vulnerability affecting Oracle WebLogic Server, a component of Oracle Fusion Middleware. The vulnerability exists in the Core component and can be exploited by unauthenticated attackers with network access via the T3 protocol. Successful exploitation allows unauthorized access to critical data or complete access to all Oracle WebLogic Server accessible data.
This vulnerability is classified as "easily exploitable," meaning attackers require no special conditions, privileges, or user interaction to compromise affected systems. The T3 protocol, which is Oracle's proprietary protocol for communication between WebLogic Server instances and Java clients, serves as the attack vector.
Critical Impact
Unauthenticated remote attackers can gain unauthorized access to sensitive data through the T3 protocol, potentially compromising all accessible data on affected Oracle WebLogic Server installations.
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
- April 18, 2023 - CVE-2023-21931 published to NVD
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2023-21931
Vulnerability Analysis
This vulnerability is categorized under CWE-306 (Missing Authentication for Critical Function), indicating that the WebLogic Server Core component fails to properly authenticate requests through the T3 protocol before allowing access to sensitive functionality. The flaw enables unauthenticated network-based attacks that can result in complete disclosure of confidential information accessible to the WebLogic Server.
The T3 protocol is WebLogic's native protocol used for RMI (Remote Method Invocation) communications. When improperly secured, it can be leveraged to bypass authentication mechanisms and directly access server resources. This vulnerability specifically impacts the confidentiality of data, with no direct impact on integrity or availability according to the published analysis.
Root Cause
The root cause of CVE-2023-21931 lies in missing authentication controls for critical functions within the Oracle WebLogic Server Core component. The T3 protocol handler does not adequately validate or authenticate incoming requests before processing them, allowing unauthenticated attackers to access protected resources and sensitive data.
Attack Vector
The attack vector is network-based, requiring no authentication, no user interaction, and presents low attack complexity. An attacker with network access to the T3 protocol port (typically port 7001 or 7002) can remotely exploit this vulnerability.
The exploitation flow involves:
- Attacker identifies an exposed WebLogic Server with T3 protocol enabled
- Malicious T3 requests are crafted targeting the vulnerable Core component
- The server processes the requests without proper authentication
- Sensitive data is disclosed to the attacker
Detailed technical analysis is available at the Packet Storm Exploit Analysis page.
Detection Methods for CVE-2023-21931
Indicators of Compromise
- Unusual T3 protocol traffic on ports 7001 or 7002 from external or unauthorized sources
- Unexpected data exfiltration patterns from WebLogic Server instances
- Anonymous or unauthenticated connection attempts in WebLogic Server access logs
- Anomalous RMI invocation patterns in server diagnostic logs
Detection Strategies
- Monitor network traffic for T3 protocol connections from untrusted networks or IP addresses
- Implement intrusion detection rules to identify known exploitation patterns targeting WebLogic T3 endpoints
- Review WebLogic Server access logs for authentication bypass attempts and unauthorized data access
- Deploy network-based anomaly detection to identify unusual data transfer volumes from WebLogic instances
Monitoring Recommendations
- Enable detailed logging for T3 protocol connections in WebLogic Server administration console
- Configure SIEM rules to alert on T3 traffic from external networks or unexpected sources
- Implement network segmentation monitoring to detect lateral movement attempts
- Regularly audit WebLogic Server configurations and access patterns for anomalies
How to Mitigate CVE-2023-21931
Immediate Actions Required
- Apply the Oracle Critical Patch Update from April 2023 immediately to all affected WebLogic Server instances
- Restrict T3 protocol access to trusted networks only using firewall rules or WebLogic connection filters
- If patching is not immediately possible, disable T3 protocol access from untrusted networks
- Conduct an assessment of potentially exposed sensitive data accessible through WebLogic Server
Patch Information
Oracle has addressed this vulnerability in the April 2023 Critical Patch Update. Administrators should apply the appropriate patches for their WebLogic Server version (12.2.1.3.0, 12.2.1.4.0, or 14.1.1.0.0). The official patch and detailed instructions are available in the Oracle Security Alert April 2023.
Workarounds
- Implement network-level filtering to block T3 protocol access from untrusted networks
- Configure WebLogic Server connection filters to restrict T3 protocol access to specific trusted IP addresses
- Consider using HTTPS/IIOP protocols instead of T3 where possible for external communications
- Deploy a web application firewall (WAF) or reverse proxy to control access to WebLogic endpoints
# Example WebLogic connection filter configuration
# Add to config.xml under <security-configuration>
# This restricts T3 access to specific trusted networks only
# Replace 10.0.0.0/8 with your trusted network range
# weblogic.security.net.ConnectionFilterImpl
# Rule format: target localAddress localPort action protocols
# Example: Allow T3 from trusted network, deny from all others
# 10.0.0.0/8 * * allow t3 t3s
# * * * deny t3 t3s
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
