Firewall Audit Logs: Analysis and 6 Steps for Improvement in 2024

Firewall logging is essential for monitoring, analyzing, and auditing network traffic to detect potential security threats and attacks at an early stage. In the realm of cybersecurity, the management and analysis of firewall audit logs play a pivotal role in fortifying network defenses and upholding regulatory standards.

Firewall audit complements logging by systematically evaluating firewall configurations, rule sets, and policies to ensure they align with security best practices and compliance requirements, further enhancing the overall security posture of an organization’s network infrastructure. Businesses looking for firewall audit solutions may explore firewall audit software.

What is firewall logging?

Firewall logging is the process of recording activities that occur within a firewall system, including the source of data packets and the protocols used. Firewall logging provides insights into network traffic, security threats and vulnerabilities. 

Firewall audit logs

Firewall audit logs offer a time-ordered account of system events, encompassing user activities, access attempts, and configuration modifications, vital for security surveillance and compliance assessments. Derived from firewall audit logs, they significantly assist in monitoring and analyzing firewall management activities.

These logs, stored in log data or a data lake, can be accessed through the web interface or command line interface. They help in generating reports, analyzing traffic patterns, and verifying security configurations.

Firewall rules and standards

Audit logs capture the implementation and execution of firewall rules, providing visibility into how the firewall is enforcing security policies and handling network traffic. In turn, adherence to established rules and standards ensures that firewall activities are aligned with security objectives, compliance requirements, and operational best practices.

For more detailed information, please refer to the article on firewall compliance.

Firewall security standards

They encompass guidelines, requirements, and specifications aimed at securing firewall configuration and management. Adhering to these standards is crucial for organizations to safeguard their internal networks from threats and enhance their security posture. Common firewall security standards include ISO, NIST, GDPR, PCI-DSS, PSD2, FINRA, SOX, DORA, DISA STIG, HIPAA, FISMA, and NERC CIP.

Firewall rules

They are also referred to as rule sets or rule bases, consisting of specific configurations within a firewall that dictate how incoming and outgoing network traffic should be handled. These rules determine whether traffic should be allowed, blocked, or redirected based on defined criteria, effectively controlling network communication and access. The five main firewall rules include deny all, least privilege, explicit allow, explicit deny, and stateful inspection.

Different levels of firewall logs

Firewall logs typically operate on a variety of levels, from low level of details to high level of details, depending on the configuration and the types of events they capture.

1. Low level of details in firewall logs

Some logs may contain basic information about network traffic like source and destination IP addresses, ports, protocols, and actions taken by the firewall (allowing or blocking traffic). These levels are suitable for monitoring authentication events and administrative change events, such as modifications to low-level kernel settings, firewall status, or user objects on a computer.

2. High level of details in firewall logs

Some other logs may provide more comprehensive insights, including user names and application names. These higher levels of logging are suitable for computers managing sensitive information or those operating in high-risk security environments, as they can help confirm potential system compromises, especially when accessing systems remotely.

Determining the appropriate log level for your firewall involves balancing your security objectives, compliance needs, and available resources. It’s crucial to strike a balance between the need for visibility and analysis and the potential impact on performance and storage requirements.

Log retention

Effective firewall logging is essential for network security, and log retention ensures that valuable information is stored for future analysis and forensic investigation purposes. Log retention refers to the practice of storing log files for a specified duration, determined by legal or operational requirements, before deletion. To ensure data integrity, logs should be archived in a specific format and stored securely offsite, using appropriate backup media based on budget and other considerations. 

Log retention periods vary based on organizational policies and the value of data. Data with little value may not be stored at all, while data important for system administration but not log management infrastructure can be kept at the system level only. Most enterprises keep audit logs, IDS logs, and firewall logs for at least two months. Some regulations mandate retention periods ranging from six months to seven years.

Figure 1: Shows the firewall management system settings on log retention

Source: AlgoSec¹

How to improve a firewall logging in 6 steps

1. Use a centralized log management system

• Utilize a centralized log management system to receive, store, normalize, and index logs from all firewalls.
• Achieve a unified view of network activity and security status for comprehensive monitoring and reporting.

This practice provides a unified view of network activity and security status for comprehensive monitoring and reporting and enables efficient log storage, normalization, and indexing from all firewalls for effective analysis.

Figure 2: Shows the control panel of a firewall management system

Source: Tufin²

2. Choose the right logging level

• Configure your firewall to log relevant network traffic based on security objectives and compliance requirements.
• Balance visibility and analysis needs with performance and storage impact.

This balances visibility and analysis needs with performance and storage impact for optimized logging.

3. Enable comprehensive logging

• Ensure all relevant network traffic is logged, including allowed and denied connections.
• Provide a complete view of network activity for effective monitoring and analysis.

This practice provides a comprehensive record of events for effective monitoring, analysis, and threat detection.

4. Enable log rotation and retention

• Implement log retention policies based on legal and operational requirements to manage log files efficiently.
• Set up log rotation to create new log files periodically and archive or delete old logs based on time or size limits.

It helps to manage log files efficiently and ensures maintaining the integrity and accessibility of audit trail logs.

5. Secure audit trail

• For secure firewall log storage, it’s advisable to store and analyze firewall logs in a centralized server rather than locally, where they are initially stored when logging is enabled.

This practice protects audit logs from unauthorized access or tampering, ensuring the accuracy and reliability of log data. The image displayed below shows an audit trail of a firewall audit software.

Figure 3: Image of audit trail of a firewall management system

Source: Tufin³

6. Apply filters and alerts

• Use filters to focus on relevant log entries and exclude noise and irrelevant information.
• Configure alerts to trigger notifications or actions for specific events or patterns, streamlining log analysis and response processes.

This approach reduces noise and irrelevant information in audit logs while enabling timely detection and response to security incidents.

FAQs

Further reading

• 3-Step Guide to Effective Firewall Audit in 2024
• Key Components of Firewall Compliance: Guidance in 2024

External Links

• 1. AlgoSecDocs. AlgoSec. Accessed: 4/April/2024.
• 2. User Guide. Tufin. Accessed: 4/April/2024.
• 3. User Guide. Tufin. Accessed: 4/April/2024.