CVE-2022-27444: MariaDB Server DoS Vulnerability

CVE-2022-27444 Overview

CVE-2022-27444 is a segmentation fault vulnerability discovered in MariaDB Server v10.9 and below. The vulnerability exists within the sql/item_subselect.cc component, which handles subselect query processing. When exploited, this vulnerability can cause the database server to crash, resulting in a denial of service condition that disrupts database availability for all connected applications and services.

Critical Impact

A remote attacker can trigger a segmentation fault in MariaDB Server, causing service disruption and potential database unavailability for dependent applications.

Affected Products

• MariaDB Server v10.9 and below
• MariaDB Server v10.2 series (prior to fix)
• MariaDB Server v10.3 through v10.8 series (prior to fix)

Discovery Timeline

• 2022-04-14 - CVE-2022-27444 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-27444

Vulnerability Analysis

This vulnerability is classified as a Null Pointer Dereference DoS issue that manifests within MariaDB's subselect query handling code. The sql/item_subselect.cc component is responsible for processing SQL subqueries, and under specific conditions, the code fails to properly validate memory references before accessing them.

When a malformed or specially crafted query is executed, the database server encounters an invalid memory access condition, resulting in a segmentation fault. This causes the MariaDB server process to terminate unexpectedly, denying service to all connected clients and applications relying on the database.

The attack can be executed remotely over the network without requiring any authentication or user interaction, making it particularly dangerous for internet-facing database deployments or environments where untrusted users can execute queries.

Root Cause

The root cause of CVE-2022-27444 lies in improper memory handling within the item_subselect.cc component. The code fails to perform adequate null pointer or boundary checks before dereferencing memory addresses during subselect query processing. This results in the operating system's memory protection mechanisms terminating the process when an invalid memory access is attempted.

Attack Vector

The vulnerability can be exploited through network-based attacks where an attacker sends specially crafted SQL queries to the MariaDB server. The attack characteristics include:

• Network-accessible: The vulnerability can be triggered remotely without physical access to the server
• No privileges required: An attacker does not need authenticated access to potentially exploit this vulnerability
• No user interaction: The attack can be executed automatically without any user action
• Availability impact: Successful exploitation results in complete denial of database service

The vulnerability specifically targets the subselect query processing pathway. An attacker would craft a malicious SQL query containing subselect statements designed to trigger the segmentation fault condition in the item_subselect.cc code path.

Detection Methods for CVE-2022-27444

Indicators of Compromise

• Unexpected MariaDB server process termination or crashes in system logs
• Segmentation fault entries in /var/log/mysql/ or MariaDB error logs referencing item_subselect.cc
• Sudden database unavailability followed by automatic restart attempts
• Core dump files generated by the MariaDB process

Detection Strategies

• Monitor MariaDB error logs for segmentation fault messages and unexpected process terminations
• Implement database query auditing to identify unusual or malformed subselect queries
• Deploy SentinelOne Singularity Platform to detect anomalous process behavior and crash patterns
• Set up alerting for MariaDB service availability and automatic restart events

Monitoring Recommendations

• Enable detailed MariaDB general query logging during investigation periods to capture potential exploitation attempts
• Configure system monitoring to alert on MariaDB process crashes and automatic restarts
• Implement network-level SQL query inspection for suspicious subselect query patterns
• Monitor for elevated connection failures that may indicate service disruption

How to Mitigate CVE-2022-27444

Immediate Actions Required

• Upgrade MariaDB Server to a patched version that addresses MDEV-28080
• Review and restrict database access to trusted networks and authenticated users only
• Implement query timeout limits to reduce impact of malicious queries
• Enable query logging to detect potential exploitation attempts

Patch Information

MariaDB has addressed this vulnerability through their issue tracking system under MDEV-28080. Organizations should consult the MariaDB release notes to identify the specific version containing the fix for their deployment branch.

Additional security guidance is available through the NetApp Security Advisory ntap-20220526-0006 for NetApp environments utilizing MariaDB.

Administrators should upgrade to the latest stable release of their MariaDB branch that includes the patch for this vulnerability.

Workarounds

• Restrict network access to the MariaDB server using firewall rules to limit exposure
• Implement application-level query validation to filter potentially dangerous subselect patterns
• Deploy a database proxy or web application firewall capable of SQL query inspection
• Limit database user privileges to the minimum required for application functionality
• Configure automatic service restart with monitoring to minimize downtime during attacks

# Configuration example - Restrict MariaDB network access
# /etc/mysql/mariadb.conf.d/50-server.cnf

# Bind MariaDB to localhost only if external access is not required
bind-address = 127.0.0.1

# Set query timeout to limit impact of malicious queries
max_statement_time = 30

# Enable general query log for monitoring (use cautiously in production)
general_log = 1
general_log_file = /var/log/mysql/general.log