CVE-2023-21980: Oracle MySQL Server Auth Bypass Flaw

CVE-2023-21980 Overview

CVE-2023-21980 is a vulnerability affecting the MySQL Server product of Oracle MySQL, specifically within the Client programs component. This vulnerability allows a low-privileged attacker with network access via multiple protocols to potentially achieve a complete takeover of the MySQL Server. Successful exploitation requires human interaction from a person other than the attacker and is considered difficult to exploit due to its high attack complexity.

Critical Impact

Successful exploitation can result in complete takeover of MySQL Server, impacting confidentiality, integrity, and availability of the database system.

Affected Products

• Oracle MySQL Server version 5.7.41 and prior
• Oracle MySQL Server version 8.0.32 and prior

Discovery Timeline

• April 18, 2023 - CVE-2023-21980 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-21980

Vulnerability Analysis

This vulnerability exists within the Client programs component of Oracle MySQL Server. The flaw enables a network-based attack that, while difficult to execute, can lead to complete server compromise. The attack requires a low-privileged account and depends on user interaction, meaning an attacker would need to convince a legitimate user to perform certain actions that trigger the vulnerability. The exploitation path involves multiple protocols, increasing the potential attack surface while simultaneously requiring more sophisticated attack planning.

The vulnerability is classified under CWE-284 (Improper Access Control), indicating that the root issue involves inadequate restrictions on access to critical system resources or functionality within the MySQL Client programs.

Root Cause

The vulnerability stems from improper access control within the MySQL Client programs component. This access control weakness allows authenticated attackers to potentially bypass security restrictions and escalate their privileges beyond intended boundaries. The specific nature of the improper access control enables attackers to gain unauthorized control over MySQL Server operations when combined with user interaction.

Attack Vector

The attack vector for CVE-2023-21980 is network-based, requiring the attacker to have low-privilege access to the target MySQL Server. The exploitation scenario involves:

1. An attacker with a valid low-privilege MySQL account establishes network connectivity to the target server
2. The attacker crafts a malicious request or payload designed to exploit the access control weakness
3. A legitimate user with higher privileges must interact with the system in a way that triggers the vulnerability
4. Upon successful exploitation, the attacker gains complete control over the MySQL Server instance

The requirement for human interaction and high attack complexity serves as limiting factors, reducing the likelihood of widespread automated exploitation. However, in targeted attack scenarios, a motivated adversary could craft convincing social engineering tactics to facilitate the required user interaction.

Detection Methods for CVE-2023-21980

Indicators of Compromise

• Unexpected privilege escalation events in MySQL audit logs showing low-privileged accounts performing administrative actions
• Anomalous network connections to MySQL servers from unusual source addresses or using unexpected protocols
• Suspicious MySQL client program executions with abnormal command-line parameters or connection patterns

Detection Strategies

• Monitor MySQL general query logs and audit logs for unusual query patterns from low-privileged accounts
• Implement network traffic analysis to detect anomalous MySQL protocol communications
• Deploy endpoint detection solutions to monitor MySQL client program behavior and flag suspicious execution patterns
• Configure SIEM rules to correlate authentication events with subsequent privilege escalation indicators

Monitoring Recommendations

• Enable MySQL Enterprise Audit or equivalent logging to capture detailed client program activity
• Implement real-time alerting for any privilege escalation events within MySQL Server
• Monitor for unusual network traffic patterns to MySQL listening ports (default 3306)
• Track user interaction events that precede any MySQL administrative operations

How to Mitigate CVE-2023-21980

Immediate Actions Required

• Upgrade Oracle MySQL Server to version 5.7.42 or later (for 5.7.x branch) or version 8.0.33 or later (for 8.0.x branch)
• Apply the Oracle Critical Patch Update from April 2023 immediately
• Review and restrict network access to MySQL Server to only trusted sources
• Audit existing MySQL user accounts and remove unnecessary low-privileged access

Patch Information

Oracle has addressed this vulnerability in their April 2023 Critical Patch Update. The official security advisory is available at the Oracle Security Alert CPUAPR2023. Organizations using MySQL in NetApp environments should also review the NetApp Security Advisory NTAP-20230427-0007 for additional guidance.

To apply the patch, administrators should:

1. Download the appropriate MySQL Server update from Oracle's official repository
2. Schedule a maintenance window for the upgrade
3. Backup existing databases before applying the update
4. Apply the update following Oracle's documented upgrade procedures
5. Verify successful patching by checking the MySQL version string

Workarounds

• Implement strict network segmentation to limit MySQL Server exposure to only essential systems
• Enforce the principle of least privilege by reviewing and minimizing user account permissions
• Deploy application-layer firewalls to monitor and filter MySQL protocol traffic
• Implement multi-factor authentication for administrative access to MySQL systems where possible

# Verify MySQL version after patching
mysql --version

# Check running server version
mysql -u admin -p -e "SELECT VERSION();"

# Review user privileges for potential over-privileged accounts
mysql -u admin -p -e "SELECT user, host, Super_priv FROM mysql.user WHERE Super_priv='Y';"