12.3 4 Configure Advanced Audit Policy

Let's delve into the intricacies of configuring Advanced Audit Policy, a crucial aspect of Windows security. Mastering this allows for granular control over what events are logged, providing invaluable insights into system activity and potential security breaches. Understanding and implementing this policy effectively is paramount for any organization striving to maintain a robust security posture and adhere to compliance requirements.

Understanding Advanced Audit Policy

The Advanced Audit Policy Configuration, introduced in Windows Vista and Windows Server 2008, provides a far more detailed and flexible approach to auditing security-related events compared to the basic audit policies. Instead of broad categories, it offers a wide range of subcategories that allow you to pinpoint specific activities to monitor. This level of precision reduces the noise generated by unnecessary audit logs, making it easier to identify genuine security concerns.

Why is it important?

• Improved Security: By focusing on specific events, you can detect malicious activities more effectively.
• Compliance: Many regulatory frameworks require detailed audit trails. Advanced Audit Policy helps meet these requirements.
• Performance: Reduces the overhead of excessive logging by focusing only on relevant events.
• Forensic Analysis: Provides comprehensive data for investigating security incidents.

Basic Audit Policies vs. Advanced Audit Policies

Traditional basic audit policies are configured under Local Security Policy (secpol.msc) under Security Settings -> Local Policies -> Audit Policy. These policies are broader and less specific.

Advanced Audit Policies, found under Local Security Policy -> Security Settings -> Advanced Audit Policy Configuration, offer a much more granular approach. They consist of several subcategories under nine main categories:

• Account Logon: Audits events related to account logon attempts.
• Account Management: Audits events related to user and group account management.
• Detailed Tracking: Provides detailed tracking of processes and other system activities.
• DS Access: Audits access to Active Directory objects.
• Logon/Logoff: Audits user logon and logoff events.
• Object Access: Audits access to specific objects like files, folders, and registry keys.
• Policy Change: Audits changes to security policies.
• Privilege Use: Audits the use of user rights and privileges.
• System: Audits system-level events like startup, shutdown, and time changes.

The key difference is the level of detail and the ability to target specific actions. For example, instead of simply auditing "Account Logon" failures, you can specifically audit "Kerberos Authentication Service" failures. This precision drastically reduces the volume of irrelevant logs.

Configuring Advanced Audit Policy: A Step-by-Step Guide

Configuring Advanced Audit Policy involves several steps, from planning and testing to implementation and monitoring. Here's a detailed guide to navigate the process:

Step 1: Planning and Defining Objectives

Before diving into configuration, you need a clear understanding of what you want to audit and why. This involves:

• Identifying Critical Assets: Determine which systems, data, and applications are most critical to your organization.
• Defining Security Threats: Identify potential threats that could target these critical assets (e.g., unauthorized access, data breaches, malware infections).
• Compliance Requirements: Understand any relevant compliance mandates (e.g., HIPAA, PCI DSS, GDPR) that dictate specific audit requirements.
• Documenting Objectives: Clearly document your audit objectives. This will serve as a guide throughout the configuration process.

For example, you might decide to audit failed logon attempts to domain controllers to detect potential brute-force attacks, or track changes to sensitive files to monitor for data tampering.

Step 2: Identifying Relevant Audit Subcategories

Based on your objectives, identify the specific audit subcategories that will provide the necessary information. This requires careful consideration of the available subcategories and their descriptions.

Let's consider a scenario where you want to audit access to a specific folder containing sensitive financial data. You would need to focus on the "Object Access" category and its subcategories, specifically:

• Audit File System: This subcategory audits access to files and folders.
• Audit Handle Manipulation: This can be helpful to track how handles to specific objects are being used.

Step 3: Choosing Audit Settings: Success, Failure, or Both

For each selected subcategory, you need to determine whether to audit success events, failure events, or both. This depends on your objectives.

• Success: Auditing success events can help track normal activities and identify patterns of use.
• Failure: Auditing failure events is crucial for detecting unauthorized access attempts, policy violations, and other security breaches.
• Both: Auditing both success and failure events provides the most comprehensive picture, but can also generate a higher volume of logs.

In our financial data folder example, you would likely audit both success and failure events for "Audit File System." Successful access might indicate legitimate use, while failed access attempts could signal unauthorized activity.

Step 4: Implementing the Audit Policy

There are several ways to implement Advanced Audit Policy:

• Local Security Policy (secpol.msc): This is suitable for configuring audit policies on individual computers.
• Group Policy Management Console (GPMC): This is the preferred method for managing audit policies in a domain environment. It allows you to apply policies consistently across multiple computers.
• Command-Line Tools (auditpol.exe): This tool provides a command-line interface for configuring and managing audit policies.

Using Group Policy (Recommended)

1. Open the Group Policy Management Console (GPMC) by typing gpmc.msc in the Run dialog box.
2. Navigate to the Organizational Unit (OU) or Domain where you want to apply the audit policy. It's generally best practice to create a dedicated OU for servers requiring specific audit settings.
3. Right-click the OU and select "Create a GPO in this domain, and Link it here...".
4. Give the GPO a descriptive name (e.g., "Advanced Audit Policy - Financial Data Server").
5. Right-click the newly created GPO and select "Edit".
6. In the Group Policy Management Editor, navigate to: Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Advanced Audit Policy Configuration.
7. Expand the desired category (e.g., "Object Access") and select the relevant subcategory (e.g., "Audit File System").
8. Double-click the subcategory and configure the audit settings (Success, Failure, or both).
9. Click "Apply" and "OK".
10. Close the Group Policy Management Editor.
11. Update Group Policy: On the target computers, run gpupdate /force in an elevated command prompt to apply the new policy.

Configuring Object Access Auditing (Specific Files/Folders)

Auditing access to specific files or folders requires an additional configuration step:

1. Enable "Audit Object Access" category: Make sure the "Audit Object Access" category (and the appropriate subcategories) is enabled in the Advanced Audit Policy as described above.
2. Configure System Access Control List (SACL): Right-click the file or folder you want to audit and select "Properties".
3. Go to the "Security" tab and click "Advanced".
4. Go to the "Auditing" tab. If you see a message saying "You must have Read permissions to view the auditing information for this object," you may need to take ownership of the object.
5. Click "Add".
6. Enter the user or group you want to audit. You can choose "Everyone" to audit all users.
7. In the "Auditing Entry" dialog box, select the types of access you want to audit (e.g., Read, Write, Delete).
8. Choose whether to audit successful access, failed access, or both.
9. Click "OK" to save the auditing entry.
10. Click "Apply" and "OK" on the Advanced Security Settings window.

Step 5: Testing the Audit Policy

Before deploying the audit policy to your entire environment, thoroughly test it in a test environment. This involves:

• Simulating Events: Perform actions that should trigger audit events (e.g., failed logon attempts, accessing restricted files).
• Reviewing Event Logs: Examine the Windows Event Logs to verify that the expected events are being logged. Look for events with the appropriate Event IDs and descriptions.
• Analyzing Log Volume: Assess the volume of generated logs. Adjust the audit policy if the volume is too high or too low.
• Identifying False Positives: Identify any events that are being logged incorrectly or unnecessarily. Fine-tune the audit policy to eliminate these false positives.

Step 6: Deployment and Monitoring

Once you're satisfied with the test results, you can deploy the audit policy to your production environment.

• Phased Rollout: Consider a phased rollout, starting with a small group of computers and gradually expanding to the entire environment.
• Centralized Log Management: Implement a centralized log management solution to collect and analyze audit logs from all computers. This will simplify monitoring and incident response. Solutions like Splunk, ELK Stack (Elasticsearch, Logstash, Kibana), and SolarWinds Security Event Manager are popular choices.
• Alerting: Configure alerts to notify you of critical security events (e.g., multiple failed logon attempts, unauthorized access to sensitive data).
• Regular Review: Regularly review your audit policy to ensure it remains effective and relevant. Adjust the policy as needed to address new threats and changing business requirements.

Step 7: Maintaining and Refining the Audit Policy

Audit policies are not a "set it and forget it" endeavor. They require ongoing maintenance and refinement.

• Analyze Event Logs Regularly: Don't just collect logs; analyze them! Look for patterns, anomalies, and potential security breaches.
• Stay Updated on Threats: Keep abreast of the latest security threats and vulnerabilities. Adjust your audit policy accordingly to detect and respond to these threats.
• Review and Update: Review your audit policy at least annually, or more frequently if your environment changes significantly.
• Feedback Loop: Establish a feedback loop between security administrators, IT staff, and business stakeholders to identify areas for improvement.

Common Mistakes to Avoid

• Enabling Too Many Audits: This can lead to excessive log volume, making it difficult to identify genuine security concerns and potentially impacting system performance.
• Not Auditing Important Events: Failing to audit critical events can leave you blind to potential security breaches.
• Ignoring the Event Logs: Collecting audit logs is useless if you don't analyze them.
• Not Testing the Audit Policy: Failing to test the audit policy can result in unexpected behavior and inaccurate data.
• Not Documenting the Audit Policy: Proper documentation is essential for understanding, maintaining, and troubleshooting the audit policy.
• Overlooking Object Access Auditing: For detailed tracking of specific files and folders, remember to configure the SACL in addition to enabling the "Audit Object Access" category.
• Using Basic Audit Policies with Advanced Audit Policies: Basic audit policies can override advanced audit policies. Disable basic audit policies when using advanced audit policies to ensure the advanced settings are enforced. You can do this by configuring the following setting within your GPO: Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> "Audit: Force audit policy subcategory settings (Windows Vista or later) to override audit policy category settings". Set this to "Enabled."

Troubleshooting Advanced Audit Policy

Even with careful planning and configuration, issues can sometimes arise with Advanced Audit Policy. Here are some common problems and how to troubleshoot them:

• No Events Being Logged:
  • Verify Audit Policy is Enabled: Double-check that the audit policy is enabled and applied correctly through Group Policy or Local Security Policy.
  • Check Event Log Size: Ensure the event logs are not full. Configure the event log settings to automatically archive or overwrite old events.
  • Verify SACL Configuration: If you're auditing object access, make sure the SACL is configured correctly on the file or folder.
  • Check for Conflicting Policies: Ensure there are no conflicting audit policies (basic vs. advanced).
• Excessive Log Volume:
  • Review Audit Settings: Re-evaluate your audit objectives and adjust the audit settings to focus on the most critical events.
  • Exclude Specific Events: Use event filtering to exclude specific events that are not relevant to your security objectives.
  • Increase Log Size: If you need to retain a high volume of logs, increase the size of the event logs.
• Incorrect Events Being Logged:
  • Verify Audit Subcategories: Double-check that you've selected the correct audit subcategories.
  • Review Event Descriptions: Carefully review the event descriptions to understand what events are being logged.
  • Test and Fine-Tune: Continue to test and fine-tune the audit policy to eliminate false positives.
• Group Policy Not Applying:
  • Verify GPO Scope: Ensure the GPO is linked to the correct OU or domain.
  • Check GPO Permissions: Verify that the target computers have permission to access the GPO.
  • Run gpupdate /force: Force a Group Policy update on the target computers.
  • Review Event Logs for Errors: Check the event logs for any errors related to Group Policy processing.

Advanced Techniques and Considerations

• Using PowerShell for Management: The auditpol.exe command-line tool can be used in conjunction with PowerShell to automate audit policy management. This allows for scripting complex configurations and deployments.

  # Example: Enable auditing for Account Logon failures
  auditpol /set /subcategory:"Kerberos Authentication Service" /failure:enable
  

• Correlation with Other Security Tools: Integrate audit logs with other security tools, such as intrusion detection systems (IDS) and security information and event management (SIEM) systems, to provide a more comprehensive security picture.

• Auditing Removable Storage: Audit access to removable storage devices to detect and prevent data leakage. Focus on the "Audit Removable Storage" subcategory under the "Object Access" category.

• Auditing Print Services: Audit print services to track who is printing what and identify potential security risks. Focus on the "Audit Print Service" subcategory under the "Object Access" category.

• Auditing Registry Access: While powerful, auditing registry access can generate a large volume of logs. Carefully select the registry keys you want to audit and focus on critical configuration settings.

Conclusion

Configuring Advanced Audit Policy is a critical step in strengthening your organization's security posture. By understanding the principles, following the steps outlined in this guide, and avoiding common mistakes, you can create a robust audit policy that provides valuable insights into system activity and helps you detect and respond to security threats effectively. Remember that audit policies are not static; they require ongoing maintenance and refinement to remain effective in the face of evolving threats. Implementing a comprehensive and well-managed Advanced Audit Policy is an investment that will pay dividends in improved security, compliance, and incident response capabilities.