CVE-2023-21893: Oracle Database Server Auth Bypass Flaw

CVE-2023-21893 Overview

CVE-2023-21893 is an Improper Access Control vulnerability affecting the Oracle Data Provider for .NET component of Oracle Database Server. This vulnerability allows an unauthenticated attacker with network access via TCPS to potentially compromise the Oracle Data Provider for .NET component. Successful exploitation requires human interaction and can result in a complete takeover of the affected component, impacting confidentiality, integrity, and availability.

Critical Impact
Successful exploitation can result in complete takeover of Oracle Data Provider for .NET, affecting confidentiality, integrity, and availability of database operations.

Affected Products

Oracle Database Server 19c
Oracle Database Server 21c
Database client-only installations on Windows platform

Discovery Timeline

2023-01-18 - CVE CVE-2023-21893 published to NVD
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-21893

Vulnerability Analysis

This vulnerability resides in the Oracle Data Provider for .NET component, which serves as the data access layer for .NET applications connecting to Oracle databases. The security weakness is classified as CWE-284 (Improper Access Control), indicating that the component fails to properly restrict access or permissions to resources.

The exploitation complexity is considered high due to specific conditions that must be met for a successful attack. The vulnerability requires the attacker to induce a user to perform an action (such as clicking a malicious link or connecting to a rogue server) while the attacker maintains network access via TCPS (TCP with SSL/TLS). Despite these requirements, successful exploitation grants the attacker significant control over the affected component.

Root Cause

The vulnerability stems from improper access control mechanisms within the Oracle Data Provider for .NET component. The component fails to adequately validate or restrict certain operations when handling TCPS connections, allowing unauthorized actions to be performed under specific conditions. This affects both full Oracle Database Server installations and standalone database client installations on Windows platforms.

Attack Vector

The attack leverages network access through TCPS (secure TCP connections). An attacker must:

Position themselves with network access to the target system
Establish or intercept TCPS communications
Induce user interaction to trigger the vulnerable code path
Exploit the improper access control to gain unauthorized access

The network-based attack vector combined with the requirement for user interaction makes this a targeted attack scenario, typically requiring social engineering or man-in-the-middle positioning. The use of TCPS suggests the vulnerability may involve certificate validation bypass or trust relationship exploitation within the secure connection handling.

Detection Methods for CVE-2023-21893

Indicators of Compromise

Unusual TCPS connection patterns to Oracle Database servers from untrusted sources
Unexpected authentication events or access attempts within Oracle Data Provider logs
Anomalous .NET application behavior when connecting to Oracle databases
Network traffic anomalies on Oracle database ports involving TCPS connections

Detection Strategies

Monitor network traffic for suspicious TCPS connections targeting Oracle Database ports
Implement application-level logging for Oracle Data Provider for .NET operations
Deploy network intrusion detection rules to identify potential exploitation attempts
Review Windows event logs for unusual .NET application behavior on database clients

Monitoring Recommendations

Enable detailed logging for Oracle Data Provider for .NET connections
Configure alerts for authentication failures or unusual access patterns
Monitor for unexpected certificate operations or trust relationship changes
Implement endpoint detection and response (EDR) solutions to track database client activity

How to Mitigate CVE-2023-21893

Immediate Actions Required

Apply the Oracle January 2023 Critical Patch Update immediately
Review and restrict network access to Oracle Database servers
Audit all systems running Oracle Database Server 19c or 21c
Verify all Windows database client installations are updated

Patch Information

Oracle has addressed this vulnerability in the January 2023 Critical Patch Update. Organizations should obtain and apply the appropriate patches from the Oracle January 2023 Security Alert. The patch addresses the improper access control issue in the Oracle Data Provider for .NET component for both database server and client-only installations.

Workarounds

Restrict TCPS network access to Oracle Database servers using firewall rules
Implement network segmentation to limit exposure of database infrastructure
Configure strict certificate validation policies for TCPS connections
Monitor and limit user access to database client applications where possible
Consider temporarily disabling unnecessary TCPS connections until patches can be applied