ISO 27001:2022 Annex A Control 8.15

Abstract of Annex A Control 8.15: Logging

Control 8.15 (Logging) in ISO/IEC 27001 focuses on ensuring that organizations record system activities and events to support security monitoring and incident response. This includes identifying what should be logged, how logs should be protected, and how they should be analyzed. Effective logging helps organizations detect anomalies, investigate potential incidents, and maintain accountability for privileged users.

Control Type

Information Security Properties

Cybersecurity Concepts

Operational Capabilities

Security Domains

Objective: Detect and Investigate Security Events

The primary objective of ISO 27001 Control 8.15 is to ensure that your organization can effectively detect and investigate security events. These objectives align with broader ISO 27001 goals by promoting proactive, detective controls that help you respond more rapidly to emerging threats.

Identify unauthorized access attempts and policy violations.
Trace root causes of incidents or disruptions.
Support forensic investigations with reliable log data.
Enhance overall security visibility to safeguard your assets.

Purpose: Strengthening Evidence and Accountability

To fulfill this objective, the purpose of Control 8.15 is multifold:

Record events and generate evidence: Through capturing relevant data in logs, you create documentation that can serve as legal or investigatory evidence.
Maintain log integrity: Proper procedures and tools protect logs from tampering, deletions, or unauthorized alterations.
Prevent unauthorized access: Ensuring only authorized individuals can view or manipulate logs.
Identify information security incidents: Quickly detect anomalies indicating cybersecurity threats, whether internal or external.
Support incident response: Provide high-quality, detailed information to bolster incident investigations and resolution.

Scope and Applicability: Where Logging Should Be Applied

When you’re determining which systems, applications, or areas of your organization should be monitored with event logging, consider the following:

Critical Systems: Servers, databases, firewalls, and any systems storing or processing sensitive data.
Applications: Mission-critical software solutions (e.g., ERP, CRM, financial applications).
Physical Access Points: Badge readers, surveillance systems, and other physical security devices that could correlate with digital events.
Cloud Environments: Cloud platforms often share logging responsibilities between you and the service provider. Ensure clarity in service-level agreements (SLAs).

Log Content and Events to Capture

When defining your logging strategy, clarity on what to log is essential. Collecting too little data can mean missing critical information, while logging everything can cause data overload. ISO 27001 Control 8.15 recommends including:

User IDs and activity details.
Dates, times, and event specifics (e.g., successful and rejected login attempts).
Device identities, system identifiers, and locations (to correlate physical and virtual assets).
Network addresses and protocols (for analyzing traffic patterns).
System and configuration changes (especially when administrative privileges are used).
File operations (creation, modification, deletion of data, and changes to access levels).
Activation or deactivation of security services (intrusion detection systems, antivirus solutions).
Application transactions (for finance, HR, or other critical operations).

Time Synchronization: Ensuring Accurate Correlation

All logs in your environment need to have synchronized timestamps for accurate event correlation. If your systems aren’t in sync, you risk confusion and delay during investigations. Consider implementing a Network Time Protocol (NTP) solution so that all devices record events in a standardized time format, making it easier to piece together timelines and sequences of events.

Protection and Retention of Logs

Access Control
One of the biggest risks to log integrity arises when privileged users (administrators or security personnel) have the ability to edit or delete their own activity records. To mitigate this, enforce strict access controls so that logs remain reliable. Only a limited set of authorized roles should have the permission to manage or delete log files.

Integrity and Security of Logs
Protect logs from tampering and corruption by:

Cryptographic Hashing: Automatically apply hashing algorithms (e.g., SHA-256) to log files so that any changes are easily detected.
Append-Only and Read-Only Storage: Store logs on write-once media or use configurations that prevent overwriting.
Public Transparency Files: Sometimes used in certificate systems, these help detect tampering by making logs publicly verifiable.

Retention Requirements
Your organization may need to retain logs for specific periods to comply with legal or regulatory mandates. Archiving older logs in secure, long-term storage helps maintain data integrity for future investigations or audits.

De-Identification for External Analysis
When sharing logs with third-party vendors (e.g., for troubleshooting), redact or mask sensitive information like usernames and IP addresses to maintain privacy while still providing enough details to resolve issues.

Privacy Considerations
Many logs contain personally identifiable information (PII). Align your processes with privacy regulations, ensuring you only store data as long as necessary and secure it from unauthorized access.

Log Analysis: Turning Data into Actionable Insights

Capturing logs is only half the battle—analysis is where you can truly gain cybersecurity value. For example, a Security Information and Event Management (SIEM) platform can automatically ingest logs from various sources, normalize the data, and highlight anomalies. Key activities include:

Monitoring for Anomalies: Baselines of “normal” behaviors can help you quickly detect significant deviations.
Correlation: Cross-reference events in your firewall logs, application logs, and physical access logs to build a complete incident timeline.
Automated Alerts: Leverage predetermined rules to trigger alerts for suspicious activity (e.g., repeated failed login attempts).
Threat Intelligence Integration: Combine your log analysis with external threat feeds to identify known malicious IPs or signatures.

Incident Response Integration: Moving from Detection to Action

When log data indicates a potential breach or anomaly, it’s imperative that your organization moves quickly to contain and investigate the threat. Integrate your logging strategy with an established incident response plan so that when suspicious activity is flagged, incident handlers:

Escalate the issue to the appropriate response team.
Preserve log evidence securely for forensic analysis.
Investigate the root cause to guide remediation efforts.
Report the incident following legal or regulatory requirements.

Other Relevant Controls

IT Operations and Security Teams
Monitor dashboards, respond to alerts, manage security tools, and coordinate with incident response.

System Owners
Collaborate on establishing baselines for normal usage. They also approve recommended controls for their systems.

Compliance and Audit Teams
Regularly review and assess monitoring systems to ensure alignment with ISO 27001 and other relevant standards or regulations.

Management
Provide budget, oversight, and policy direction to uphold a culture of security awareness throughout the organization.

Integration with Other Controls

everal other ISO 27001 controls work hand-in-hand with Control 8.15:

Control 5.25: Information Security Incident Management – Ensures systematic handling of security events once they’re discovered.
Control 5.28: Collection of Evidence – Guides how logged data should be handled to remain admissible in legal investigations.
Control 5.34: Privacy and Protection of PII – Critical if logs contain personal data.
Control 8.11: Data Masking – Supports the redaction or obfuscation of sensitive information before sharing logs externally.
Control 8.16: Monitoring Activities – Leverages logs as input for real-time monitoring solutions and threat intelligence.
Control 8.17: Clock Synchronization – Ensures logs maintain consistent timestamps for accurate event correlation.

Templates That May Assist with This Control

On your journey to implement ISO 27001 Control 8.15, you can streamline your efforts using handy templates, such as:

Logging Policy Template
Outlines the policies, roles, and responsibilities for event logging across your organization.
SIEM Configuration Checklist
Provides guidelines to configure your SIEM system, including log source selection and rule tuning.
Log Review Procedure Template
Describes the frequency, methods, and escalation process for reviewing log data regularly.
Incident Response Log Collection Template
Ensures a systematic approach when collecting logs during or after a suspected security incident.

Implementation Tips and Best Practices

Start with Critical Systems
Prioritize logging on servers and applications that host sensitive data or support key business functions.
Automate Analysis
Incorporate SIEM solutions or advanced analytics to handle large volumes of logs and highlight anomalies in real time.
Regularly Review and Update
Security threats evolve quickly. Schedule periodic reviews of your logging strategy, including retention periods, log sources, and analysis rules.
Test and Validate
Run drills or tabletop exercises to verify that your log management process and incident response plan work seamlessly when faced with real threats.
Collaborate Across Teams
Log management isn’t solely an IT or security function. Work with business units, legal, and compliance teams to address regulatory requirements and privacy considerations.