Security Event Logs: Importance, best practices, and management

Logs help identify anomalies that may signal a breach early on, such as repeated login failures or unusual network activity.

In the aftermath of a security incident, security event logs provide the evidence trail needed to identify what happened, when, and how.

Regulatory frameworks such as GDPR, HIPAA, PCI DSS, and ISO 27001 mandate that organizations retain and monitor logs to demonstrate security and accountability.

Security logs can serve as legal evidence in disputes or investigations, ensuring actions are traceable to specific users or systems.

Beyond security, logs provide valuable insights into system performance and usage, enabling IT administrators to identify issues such as misconfigurations and policy violations.

Security log sources produce massive amounts of data, making storage and analysis difficult. Important security events can easily get lost in a "sea of data" if not properly managed. Implementing log management best practices helps to reduce the strain on system resources and personnel.

Not all log events indicate a threat. However, you often still need to log events for regular activity for security and compliance purposes. Sorting through benign versus suspicious events can be overwhelming.

Logs from different sources come in various formats, making it hard to correlate events across systems. Normalizing and aggregating data from disparate sources is challenging, and you need the right tools to ingest and centralize the logs.

Attackers can delete or tamper with logs to cover their tracks. Ensuring log integrity and limiting access to logs is critical. For example, Windows logs event ID 1102 whenever the security audit log is cleared. This event is one of the top 5 events to monitor.

Different regulations require different retention periods and data protection standards, adding complexity to log storage and access control. You must find the right balance to meet data retention requirements while managing costs and privacy.

Analyzing logs requires expertise in threat detection, system behavior, and the use of security tools. These skills are in high demand but short in supply. Nowadays, automating log analysis, for example, by using a SIEM, is a necessity.

Utilize a centralized logging solution, such as NXLog Platform, to collect logs from across your infrastructure. Normalizing and aggregating your logs in a central location simplifies analysis and enables the correlation of events from different sources.

Set up real-time security log monitoring to detect and alert on suspicious activity, such as multiple failed logins within a short period, turning off antivirus software, and the creation of new administrative accounts. Real-time threat detection is crucial for catching incidents as they happen, not weeks or months later.

Filtering logs at the source helps you reduce the data volume. For example, you can use NXLog Agent to discard non-actionable logs or route logs to different destinations based on log levels.

Protect logs in transit and at rest by using encryption, user access control, and checksums to detect tampering. Additionally, back up your logs to a secondary secure storage location, preferably off-site. Maintaining log data integrity is paramount. If it’s easy to alter the logs, they lose their value.

Define clear log retention policies based on business, legal, and regulatory requirements to ensure compliance. For example, store recent logs in a readily accessible location and archive older logs in a cost-effective storage solution. Automate log rotation and archival according to your policy to minimize manual effort and prevent disruptions to your logging infrastructure.

Schedule routine log reviews to identify patterns and long-term trends. This practice helps spot slow-moving attacks or policy violations that real-time systems might miss. For example, a gradual increase in failed logins over months may indicate a slow brute-force attack.

Utilize machine learning and behavioral analytics to identify anomalies and enhance threat detection. Most SIEM and EDR systems today feature built-in machine learning and pattern detection capabilities, along with automated response features. These tools can help flag and contain threats based on security log data before human intervention.

Document your security logging policy, including which events are logged and why, how long to retain logs, who can access them, and how often they should be reviewed. Documenting procedures ensures consistency and accountability. Regularly review and update your policy as your business needs evolve, for example, to address emerging threats or the adoption of new systems.

SIEM platforms, such as Splunk, Graylog, Microsoft Sentinel, and Google SecOps, analyze security events in real time and provide data visualization, correlation, and alerting capabilities. SIEMs rely on receiving high-quality data, which typically requires an intermediate log collector, such as NXLog Agent, to sanitize the data before forwarding it to the SIEM.

Log collectors, such as NXLog Agent and Fluentd, specialize in collecting, transforming, and forwarding logs to SIEMs or data lakes. They help unify disparate log formats and reduce data ingestion costs. Solutions like NXLog Platform can be used in conjunction with a SIEM platform, aggregating logs in a centralized location while feeding the SIEM with critical security event logs.

Many modern EDR and network monitoring systems include built-in logging capabilities and can export logs to a SIEM platform. These platforms are often easier to integrate and manage in smaller environments.

Cloud providers offer native logging tools, such as AWS CloudTrail, Azure Monitor, and Google Cloud Logging. These services are tailored for cloud-native applications and often provide APIs to integrate with third-party systems. For example, NXLog Agent can pull logs from these services and forward them to a SIEM.