How effective logging of information systems can help you meet the challenge of cyberattacks

The pivotal role of logging in cybersecurity

Logging of information systems forms the cornerstone of cybersecurity. Within any information system (IS), every action executed - from data access to file modifications - constitutes a security event that requires meticulous recording.

This process, known as logging, involves the generation of log files which capture all actions, their initiators, and the precise timestamps. Effective logging ensures traceability, accountability, and a solid evidential base for addressing security incidents.

Logs serve multiple critical purposes:

• Incident detection: Log files enable the identification of anomalous activities, such as unauthorised access attempts or irregular data movements, which may indicate that a cyberattack is in progress.
• Post-incident analysis: Forensic analysis relies heavily on logs to reconstruct events, trace exploited vulnerabilities and understand attack vectors. Consider, for instance, a breach involving unauthorised data exfiltration; without detailed logs, identifying how and when the breach occurred would be nearly impossible.
• Regulatory compliance: Regulations such as the General Data Protection Regulation (GDPR) necessitate comprehensive logging practices to ensure data access and modification records are available for audits or investigations.

Synchronising time: the hidden backbone of logging

For logging to be truly effective, consistency and precision in timestamps are very important. The task of accurately timestamping events is the role of time servers, which synchronise clocks across an organisation’s entire IT infrastructure. Without precise timekeeping, logs become unreliable. A minor drift in one system’s clock can result in discrepancies that obscure the true sequence of events, potentially derailing forensic investigations.

Consider an example: imagine a scenario where a critical database is accessed after hours. If timestamps between systems aren’t accurately aligned, it may be impossible to determine whether the access was legitimate or malicious.

Time servers, particularly those using the Network Time Protocol (NTP), eliminate these ambiguities, ensuring that all actions are recorded with high temporal accuracy. Accurate timestamps are more than a convenience, they are a legal requirement when logs are used as evidence in court proceedings.

Best practices for robust and secure logging

To maximise the effectiveness of logging, certain best practices must be observed. In France, the National Agency for the Security of Information Systems (ANSSI) offers detailed guidelines, which can serve as a reference point for organisations worldwide:

• Log integrity: logs are prime targets for tampering during cyberattacks, as attackers often seek to erase evidence of their actions. To mitigate this risk, organisations should implement encryption and digital signatures for logs. Such measures ensure that any tampering attempts can be detected. Synchronisation protocols, like NTS (Network Time Security) for NTP, further bolster log integrity by safeguarding the time synchronisation process.
• Granular yet manageable log configuration: effective logging strikes a balance between detail and manageability. Excessively granular logs may generate an unmanageable volume of data, obscuring critical insights and complicating analysis. Conversely, insufficient granularity may omit essential information, leaving gaps in the security trail.
• Strategic log retention policies: effective logging also involves smart data management. Logs should be retained for a period consistent with legal requirements and the organisation’s operational needs. No more no less.
• Continuous monitoring and analysis: proactive log analysis is a cornerstone of effective threat detection. Real-time monitoring, often achieved through Security Information and Event Management (SIEM) tools, allows organisations to detect and respond to threats as they unfold, rather than after the fact. Such systems enable the correlation of events, identification of patterns, and automated alerts, enhancing situational awareness.

Challenges in implementing effective logging

Logging is of the utmost importance, but presents several challenges. One of the most significant is the volume of data generated, which can overwhelm storage systems and analysis tools if not carefully managed. Moreover, the evolving nature of cyber threats demands continuous adaptation and updating of logging practices. For instance, attacks targeting supply chain vulnerabilities may introduce new logging requirements to capture interactions across disparate, but connected, systems.

A new challenge is that logging must now extend beyond traditional IT infrastructure to encompass emerging technologies such as the Internet of Things (IoT). IoT devices, with their often-limited processing capabilities, can pose unique challenges for logging due to resource constraints and connectivity issues. As these devices become fully integrated into critical infrastructure, ensuring full logging coverage is necessary.

It's a wrap! Proactive cybersecurity is possible with effective logging

Implementing a robust logging strategy is not a miracle medicine to avoid cyberattacks. By adhering to best practices and using accurate and synchronised logs, organisations can however enhance their resilience against cyber threats.

Logging provides the insights necessary to detect, understand, and mitigate attacks, ultimately giving a better overall security for a whole organisation. While attackers may evolve, effective logging ensures they leave a trail. If a trail exists, it can be analysed, understood, and used to build defence strategies against future threats. Otherwise, nothing is possible.