CVE-2023-40933: Nagios XI SQL Injection Vulnerability

CVE-2023-40933 Overview

CVE-2023-40933 is a SQL injection vulnerability affecting Nagios XI version 5.11.1 and below. This security flaw allows authenticated attackers who possess announcement banner configuration privileges to execute arbitrary SQL commands via the ID parameter sent to the update_banner_message() function. The vulnerability enables malicious actors to manipulate database queries, potentially leading to unauthorized data access, data modification, or complete database compromise.

Critical Impact

Authenticated attackers can execute arbitrary SQL commands against the underlying database, potentially compromising sensitive monitoring data, user credentials, and system configurations stored within Nagios XI.

Affected Products

• Nagios XI version 5.11.1 and earlier versions
• All Nagios XI installations where users have announcement banner configuration privileges

Discovery Timeline

• 2023-09-19 - CVE-2023-40933 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-40933

Vulnerability Analysis

This SQL injection vulnerability exists within the update_banner_message() function in Nagios XI. The function fails to properly sanitize the ID parameter before incorporating it into SQL queries, creating an injection point that authenticated attackers can exploit. The vulnerability requires the attacker to have valid credentials and specific privileges (announcement banner configuration access), which limits the attack surface but still presents a significant risk in environments where multiple administrators or operators have access to the Nagios XI interface.

The exploitation of this vulnerability can lead to complete database compromise. An attacker could extract sensitive information including user credentials, monitoring configurations, host and service data, and potentially pivot to other systems within the monitored infrastructure. Additionally, the attacker could modify or delete critical monitoring data, potentially masking malicious activity or disrupting IT operations.

Root Cause

The root cause of CVE-2023-40933 is improper input validation and sanitization of the ID parameter within the update_banner_message() function. The application fails to implement parameterized queries or prepared statements, instead directly concatenating user-supplied input into SQL statements. This classic CWE-89 (Improper Neutralization of Special Elements used in an SQL Command) vulnerability allows attackers to break out of the intended query structure and inject malicious SQL code.

Attack Vector

The attack is conducted over the network by an authenticated user with announcement banner configuration privileges. The attacker crafts a malicious request containing SQL injection payloads within the ID parameter when interacting with the banner message update functionality. Since no user interaction is required beyond the attacker's own actions, and the attack complexity is low, exploitation can be straightforward once an attacker obtains the necessary credentials and permissions.

The vulnerability affects the confidentiality, integrity, and availability of the system—attackers can read sensitive data, modify database contents, and potentially cause service disruption through destructive SQL commands.

Detection Methods for CVE-2023-40933

Indicators of Compromise

• Unusual SQL syntax or special characters appearing in web server access logs related to banner message update endpoints
• Database query logs showing unexpected or malformed queries originating from the Nagios XI application
• Unexpected changes to announcement banner configurations or database records
• Authentication anomalies followed by banner-related API calls from unusual IP addresses

Detection Strategies

• Implement web application firewall (WAF) rules to detect SQL injection patterns in HTTP requests targeting Nagios XI
• Monitor database audit logs for queries containing SQL injection signatures such as UNION SELECT, OR 1=1, or comment sequences
• Deploy intrusion detection system (IDS) signatures specific to Nagios XI exploitation attempts
• Analyze application logs for repeated failed or unusual requests to the banner message update functionality

Monitoring Recommendations

• Enable detailed logging for all administrative actions within Nagios XI, particularly those involving banner configuration changes
• Configure alerting for any database errors or exceptions that may indicate injection attempts
• Implement user behavior analytics to detect anomalous activity from accounts with banner configuration privileges
• Regularly audit user accounts with elevated privileges to ensure principle of least privilege is maintained

How to Mitigate CVE-2023-40933

Immediate Actions Required

• Upgrade Nagios XI to a patched version that addresses this SQL injection vulnerability
• Review and restrict user accounts with announcement banner configuration privileges to only those who absolutely require this access
• Implement network segmentation to limit access to the Nagios XI administrative interface
• Enable comprehensive logging and monitoring for all Nagios XI administrative activities

Patch Information

Nagios has released security updates to address this vulnerability. Administrators should consult the Nagios Security Products Overview for official patch information and upgrade instructions. It is strongly recommended to upgrade to a version newer than 5.11.1 that contains the fix for this SQL injection vulnerability. For detailed technical analysis of this and related vulnerabilities, refer to the Outpost24 Blog on Nagios Vulnerabilities.

Workarounds

• Temporarily revoke announcement banner configuration privileges from all non-essential user accounts until patching can be completed
• Implement additional input validation at the web application firewall level to filter SQL injection patterns
• Restrict network access to the Nagios XI administrative interface using firewall rules or VPN requirements
• Consider temporarily disabling the banner message functionality if operationally feasible until the patch is applied

# Example: Restrict access to Nagios XI admin interface via iptables
# Allow only specific trusted management networks
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Verify Nagios XI version to confirm vulnerability status
cat /usr/local/nagiosxi/var/xiversion