CVE-2023-2636: AN Gradebook WordPress SQLi Vulnerability

CVE-2023-2636 Overview

CVE-2023-2636 is a SQL Injection vulnerability affecting the AN_GradeBook WordPress plugin through version 5.0.1. The plugin fails to properly sanitize and escape a parameter before using it in a SQL statement, allowing authenticated attackers with roles as low as subscriber to execute arbitrary SQL queries against the WordPress database. This vulnerability poses a significant risk to WordPress installations using this plugin, as it could lead to unauthorized data access, modification, or complete database compromise.

Critical Impact

Authenticated users with low-privilege roles (subscriber level) can exploit this SQL injection flaw to extract sensitive data from the WordPress database, modify records, or potentially escalate their access within the application.

Affected Products

• AN_GradeBook WordPress plugin versions up to and including 5.0.1
• WordPress installations with AN_GradeBook plugin enabled
• Educational WordPress sites using AN_GradeBook for grade management

Discovery Timeline

• 2023-07-17 - CVE-2023-2636 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-2636

Vulnerability Analysis

This SQL Injection vulnerability occurs due to improper input validation in the AN_GradeBook WordPress plugin. The plugin processes user-supplied input without adequate sanitization before incorporating it into SQL queries. WordPress plugins that handle database operations must utilize prepared statements and parameterized queries to prevent SQL injection attacks; however, this plugin fails to implement these security controls properly.

The vulnerability is particularly concerning because it can be exploited by users with minimal privileges. WordPress subscriber accounts, which typically have very limited capabilities, can leverage this flaw to interact directly with the database. This represents a significant security boundary violation, as subscribers should not have any direct database access.

Root Cause

The root cause of CVE-2023-2636 is the failure to properly sanitize and escape user input before incorporating it into SQL statements. The plugin does not utilize WordPress's built-in $wpdb->prepare() function or equivalent parameterized query mechanisms, allowing attackers to inject malicious SQL code through untrusted input parameters. This is a classic example of CWE-89 (Improper Neutralization of Special Elements used in an SQL Command).

Attack Vector

The attack vector is network-based, requiring authentication with at least subscriber-level privileges on the WordPress installation. An attacker can craft malicious requests containing SQL injection payloads targeting the vulnerable parameter in the AN_GradeBook plugin. Upon successful exploitation, the attacker can:

1. Extract sensitive information from the WordPress database, including user credentials and personal data
2. Modify or delete existing records in the gradebook or other database tables
3. Potentially escalate privileges by modifying user roles in the database
4. In some configurations, achieve command execution through database features like INTO OUTFILE or user-defined functions

The vulnerability is exploited by manipulating the unsanitized parameter to break out of the intended SQL query structure and inject arbitrary SQL commands. Technical details and proof-of-concept information are available in the Packet Storm SQL Injection Exploit publication.

Detection Methods for CVE-2023-2636

Indicators of Compromise

• Unusual SQL error messages in WordPress debug logs or web server error logs indicating malformed queries
• Unexpected database queries containing SQL metacharacters such as single quotes, UNION statements, or comment sequences (--, /**/)
• Anomalous activity from subscriber-level accounts accessing gradebook functionality with suspicious parameters
• Database audit logs showing queries that deviate from normal AN_GradeBook plugin patterns

Detection Strategies

• Deploy a Web Application Firewall (WAF) with SQL injection detection rules to identify and block malicious payloads targeting WordPress installations
• Enable WordPress debug logging and monitor for SQL-related errors that may indicate exploitation attempts
• Implement database query monitoring to detect unauthorized or anomalous SQL statements originating from web application traffic
• Use SentinelOne Singularity to monitor for suspicious process activity and database interactions on WordPress hosting servers

Monitoring Recommendations

• Configure real-time alerting for SQL injection patterns in web server access logs and WordPress plugin activity
• Monitor user account activity for subscriber-level accounts exhibiting unusual behavior or accessing administrative functions
• Establish baseline metrics for normal AN_GradeBook database queries and alert on deviations
• Review WordPress user audit logs for signs of privilege escalation following gradebook access

How to Mitigate CVE-2023-2636

Immediate Actions Required

• Disable or remove the AN_GradeBook plugin immediately if it is installed on your WordPress site
• Audit WordPress user accounts to identify any unauthorized changes or suspicious subscriber accounts
• Review database logs for evidence of exploitation and assess whether sensitive data may have been accessed
• Implement WAF rules to block SQL injection attempts while determining a long-term remediation strategy

Patch Information

At the time of this advisory, no official patch has been confirmed for the AN_GradeBook plugin. The vulnerability affects version 5.0.1 and earlier. Website administrators should check the WPScan Vulnerability Report for the latest status on available fixes. If no patch is available, consider migrating to an alternative gradebook solution that follows secure coding practices.

Workarounds

• Remove or deactivate the AN_GradeBook plugin until an official security patch is released by the vendor
• Restrict subscriber registration on WordPress sites using this plugin to limit potential attackers with authenticated access
• Implement network-level controls to limit access to WordPress admin areas and plugin functionality from trusted IP addresses only
• Deploy ModSecurity or similar WAF with OWASP Core Rule Set to detect and block SQL injection attempts

# WordPress CLI command to deactivate the vulnerable plugin
wp plugin deactivate an_gradebook --path=/var/www/html/wordpress

# Verify plugin is deactivated
wp plugin list --path=/var/www/html/wordpress | grep an_gradebook