Audit and Accountability

The Audit and Accountability family in NIST 800-171 Rev 2 is designed to ensure that organizations have the ability to track, monitor, and analyze activities within their information systems. By logging events and auditing system activity, organizations can detect unauthorized access, identify anomalies, and maintain accountability for user actions, which is critical for protecting Controlled Unclassified Information (CUI).

This family includes requirements for logging events, protecting audit data, and using audits to support incident investigation and ensure compliance with security policies.

Key Audit and Accountability Requirements in NIST 800-171 Rev 2:

The Audit and Accountability family contains nine security requirements, which are divided into basic and derived requirements. These requirements help organizations capture and protect audit logs, monitor system activity, and ensure that users are held accountable for their actions.

1. Create and Retain Audit Logs (3.3.1):

Basic Requirement: Organizations must generate audit records that log the creation, modification, and deletion of key data and system activities, especially those related to CUI.

Key Focus:

• Record critical system events, such as login attempts (successful and unsuccessful), file access, and configuration changes.

• These logs provide a record of who did what and when, which can be crucial for detecting suspicious behavior or conducting incident investigations.

Example: Logging login attempts, file access, and system changes across servers and user devices.

2. Ensure Users are Held Accountable (3.3.2):

Derived Requirement: Organizations must ensure that individual users are held accountable for their actions. This involves linking user actions to specific individuals and ensuring that users can be identified in audit logs.

Key Focus:

• User accountability: By tying specific actions to individual users, organizations can track the origins of any suspicious activities or security breaches.

• User identification helps prevent unauthorized actions from going unnoticed.

Example: Using unique user IDs and logging system access for accountability and traceability.

3. Configure Logs to Capture Important Events (3.3.3):

Derived Requirement: Organizations must configure systems to capture specific types of events that are relevant to security and compliance, such as access to CUI, login/logout attempts, and changes to system configurations.

Key Focus:

• Ensure that audit logs are configured to capture security-relevant events, such as access to sensitive data, account creation, or privilege escalation.

Example: Setting up systems to record changes to user roles, password updates, and unauthorized access attempts.

4. Review and Analyze Audit Logs (3.3.4):

Derived Requirement: Regularly reviewing and analyzing audit logs is essential to detect unusual or unauthorized activities and identify potential security incidents.

Key Focus:

• Organizations should implement processes to routinely examine audit logs for suspicious behavior or deviations from normal system usage.

• Automated tools may assist in monitoring logs and generating alerts for abnormal activities.

Example: Security personnel conducting weekly reviews of access logs and system alerts for signs of unauthorized access or misuse.

5. Alert on Security Events (3.3.5):

Derived Requirement: The system must be capable of generating real-time alerts or notifications when predefined security events occur, such as multiple failed login attempts, unauthorized access to CUI, or system anomalies.

Key Focus:

• These alerts ensure that security personnel are immediately aware of potential security incidents and can take swift action.

Example: Automatically generating alerts for system administrators when an unusual spike in access requests to CUI is detected.

6. Correlate and Analyze Audit Data Across Systems (3.3.6):

Derived Requirement: Organizations must be able to correlate and analyze audit data across multiple systems to identify broader patterns and threats.

Key Focus:

• It’s important to be able to combine and analyze logs from various systems (e.g., servers, endpoints, firewalls) to detect coordinated attacks or other suspicious activities that might not be visible within a single system’s logs.

Example: Aggregating logs from firewalls, servers, and applications to detect complex attack patterns.

7. Provide Protection for Audit Logs (3.3.7):

Derived Requirement: Organizations must protect audit logs from tampering, unauthorized access, or deletion to ensure their integrity and availability for analysis.

Key Focus:

• Ensure that only authorized personnel can access or modify audit logs.

• Implement protections to prevent logs from being altered or deleted by unauthorized users.

Example: Encrypting audit logs and restricting access to security administrators only.

8. Limit Audit Log Data Retention (3.3.8):

Derived Requirement: Organizations must retain audit logs for a sufficient period to allow for historical analysis and investigations, while also limiting unnecessary retention of logs that could pose a security risk.

Key Focus:

• Establish a log retention policy to keep audit data for a specified period (e.g., six months or one year) to support investigations and compliance audits.

• Ensure that logs are securely deleted after the retention period to prevent unauthorized access.

Example: Keeping audit logs for one year for investigative purposes and securely archiving or deleting them after that time.

9. Ensure Audit Logs are Reviewed for Anomalies (3.3.9):

Derived Requirement: Organizations must ensure that audit logs are regularly reviewed to identify anomalous or suspicious activities that may indicate a security breach or misuse of the system.

Key Focus:

• Routine log reviews help detect unusual patterns, such as repeated failed login attempts, large file transfers, or unauthorized access to sensitive data.

• Automated tools can help with the continuous monitoring of logs for specific anomalies.

Example: Using SIEM (Security Information and Event Management) systems to automatically flag anomalies for security teams to review.

Importance of the Audit and Accountability Family:

Detecting Security Incidents: Audit logs are essential for detecting security incidents and breaches. By capturing key events and monitoring for unusual activity, organizations can identify and respond to threats more quickly.

Supporting Investigations: In the event of a security incident, audit logs provide a detailed trail of activity, allowing security personnel to understand the scope and impact of the breach, identify the source, and take corrective actions.

Ensuring Accountability: By tying user actions to specific individuals, audit logs create a clear record of who is responsible for each action within a system. This helps enforce accountability and prevents unauthorized access or abuse of privileges.

Compliance: Many regulations and security standards, such as NIST 800-171, require organizations to maintain audit logs and ensure the integrity and availability of those logs for auditing purposes.

Proactive Monitoring: Regular review and analysis of audit logs can help organizations identify emerging threats or vulnerabilities before they escalate into major security incidents.

Best Practices for Implementing Audit and Accountability:

• Define Key Events: Ensure that your systems log critical security-relevant events, including access to CUI, privilege escalation, and failed login attempts.

• Use SIEM Tools: Implement Security Information and Event Management (SIEM) tools to aggregate and analyze logs across your entire network for anomalies and patterns.

• Automate Alerts: Set up automated alerts for critical events, such as multiple failed login attempts or access to sensitive data outside of normal working hours.

• Regular Log Review: Conduct regular, scheduled reviews of audit logs to detect any abnormal activities that could indicate a security breach.

• Protect Logs: Ensure that logs are encrypted and protected from unauthorized access or tampering. Only authorized security personnel should have access to them.

• Retain Logs Securely: Store audit logs for a predefined retention period, and ensure secure deletion or archiving after that period.

Summary:

The Audit and Accountability family in NIST 800-171 Rev 2 focuses on ensuring that organizations can track, monitor, and analyze activities on their systems to detect unauthorized access, ensure accountability, and respond to security incidents effectively. By implementing robust logging, protection of audit data, and regular log reviews, organizations can maintain the integrity of their systems and protect CUI from unauthorized access or misuse.