CVE-2023-22007: Oracle MySQL Server Replication DoS Flaw

CVE-2023-22007 Overview

CVE-2023-22007 is a Denial of Service vulnerability in the MySQL Server product of Oracle MySQL, specifically affecting the Server: Replication component. This vulnerability allows a high-privileged attacker with network access to cause a complete denial of service condition, resulting in a hang or frequently repeatable crash of the MySQL Server.

Critical Impact

Successful exploitation enables attackers with administrative privileges to completely disrupt MySQL database availability, potentially causing significant business disruption for organizations relying on MySQL replication for high availability and data redundancy.

Affected Products

• Oracle MySQL Server version 5.7.41 and prior
• Oracle MySQL Server version 8.0.32 and prior
• MySQL Server installations utilizing replication functionality

Discovery Timeline

• July 18, 2023 - CVE-2023-22007 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-22007

Vulnerability Analysis

This vulnerability resides in the MySQL Server's Replication component, which is responsible for synchronizing data between MySQL database instances. The flaw allows an authenticated attacker with high privileges (such as database administrator access) to exploit the replication mechanism in a way that causes the server to hang or crash repeatedly.

The vulnerability is easily exploitable, requiring no user interaction beyond the attacker's initial access. The attack can be performed over the network using multiple protocols supported by MySQL, making it accessible from remote locations where network connectivity to the MySQL server exists.

The impact is exclusively on availability—there is no compromise of data confidentiality or integrity. However, the complete denial of service nature means that successful exploitation can render the MySQL server entirely unavailable to legitimate users and applications.

Root Cause

The root cause stems from improper handling within the MySQL Server's Replication component. While Oracle has not disclosed specific technical details about the underlying flaw, the vulnerability classification indicates an issue in how the replication subsystem processes certain requests or conditions. When triggered by a privileged user, this causes resource exhaustion or an unhandled exception state that leads to server instability.

Attack Vector

The attack vector is network-based, meaning an attacker must have network connectivity to the vulnerable MySQL server. The exploitation requires:

1. High-privileged access to the MySQL server (administrative or replication-specific privileges)
2. Network access to the MySQL server via supported protocols (TCP/IP, named pipes, shared memory)
3. Ability to interact with the Replication component through crafted requests

The attack does not require user interaction and has low complexity, making it straightforward to execute once the prerequisite privileges are obtained. Organizations should be particularly concerned about insider threats or scenarios where administrative credentials may have been compromised.

Detection Methods for CVE-2023-22007

Indicators of Compromise

• Unexpected MySQL server crashes or hangs, particularly during replication operations
• Abnormal replication-related queries or commands in MySQL audit logs from privileged accounts
• Repeated connection attempts or unusual activity patterns from administrative database accounts

Detection Strategies

• Enable MySQL audit logging to capture all privileged operations, especially those involving replication commands
• Monitor for unusual patterns of replication-related commands such as CHANGE MASTER, START SLAVE, or replication status queries
• Implement database activity monitoring to alert on high-privilege account activity outside normal business patterns

Monitoring Recommendations

• Configure alerting for MySQL server crashes and unexpected restarts through system monitoring tools
• Monitor MySQL error logs for replication-related errors or warnings that precede service disruptions
• Track authentication events for administrative accounts and correlate with any subsequent replication component activity

How to Mitigate CVE-2023-22007

Immediate Actions Required

• Apply the Oracle Critical Patch Update from July 2023 to all affected MySQL Server installations
• Review and restrict high-privilege database accounts to only those users who absolutely require administrative access
• Implement network segmentation to limit which hosts can connect to MySQL servers with administrative credentials
• Enable comprehensive audit logging to track privileged operations on MySQL servers

Patch Information

Oracle has addressed this vulnerability in the Oracle July 2023 Critical Patch Update. Organizations should upgrade to MySQL Server versions released after July 2023 that include the fix. For MySQL 5.7, upgrade to version 5.7.42 or later. For MySQL 8.0, upgrade to version 8.0.33 or later. Additional information is available in the NetApp Security Advisory NTAP-20230725-0005.

Workarounds

• Restrict network access to MySQL servers using firewall rules to allow only trusted administrative hosts
• Implement the principle of least privilege by reviewing and minimizing accounts with replication-related privileges
• Consider using MySQL Enterprise Firewall to create whitelists of approved SQL statements for privileged accounts
• Deploy MySQL in a high-availability configuration with automatic failover to minimize the impact of potential DoS attacks

# Example: Restrict administrative access at the network level
# Add firewall rules to limit MySQL administrative access
iptables -A INPUT -p tcp --dport 3306 -s trusted_admin_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 3306 -j DROP

# Review privileged accounts in MySQL
mysql -u root -p -e "SELECT user, host FROM mysql.user WHERE Super_priv='Y' OR Repl_slave_priv='Y' OR Repl_client_priv='Y';"