How to Use Logs for Better Threat Detection

In an era where cyber threats are more sophisticated and relentless than ever, having a strong logging strategy isn’t just helpful – it’s essential. Whether you’re a UK-based SME or part of a larger enterprise, using logs effectively can mean the difference between quickly detecting a threat and suffering a costly data breach.

Here’s how to use logs for better threat detection and security response.

1. Understand What to Log – and Why

Not all logs are created equal. Start by identifying which data sources provide the most value. Key log types for threat detection include:

• Firewall and IDS/IPS logs: Show attempted intrusions or unauthorised access.

• Authentication logs: Help identify brute-force attacks or suspicious login patterns.

• Endpoint logs: Reveal malware infections, lateral movement, and insider threats.

• Application logs: Expose misuse or vulnerabilities within your own software stack.

• Cloud service logs (e.g., AWS CloudTrail, Azure Activity Logs): Essential if you’re working in hybrid or cloud environments.

The UK’s NCSC (National Cyber Security Centre) advises organisations to collect logs from systems that handle sensitive data, public-facing services, and administrative tools.

2. Centralise and Normalise Your Logs

Manually reviewing logs from different sources is inefficient and error-prone. Instead:

• Use a SIEM (Security Information and Event Management) solution like Splunk, Microsoft Sentinel, or Elastic Security to aggregate logs in one place.

• Ensure logs are normalised – that is, converted to a standard format – so they can be correlated across different systems.

This centralisation allows for real-time monitoring, alerting, and threat hunting.

3. Define and Monitor for Suspicious Behaviour

Once logs are flowing into your SIEM, define detection rules for suspicious activity. Examples include:

• Multiple failed login attempts followed by a successful one.

• Logins at unusual hours or from unexpected locations (e.g., a UK-based user logging in from Russia or North Korea).

• Sudden spikes in data transfers or file access.

• Use of admin tools (like PowerShell or PsExec) on non-administrative machines.

Use MITRE ATT&CK tactics as a framework to build these detection rules around real-world attacker behaviours.

4. Set Up Alerts – But Avoid Alert Fatigue

Getting notified about a genuine security event is great – but being buried under a mountain of false positives isn’t.

• Prioritise high-fidelity alerts – those with strong indicators of compromise.

• Use threat intelligence feeds to enrich alerts with contextual information (e.g., whether an IP address is associated with known threat actors).

• Implement alert tuning over time to cut down on noise.

5. Establish a Retention Policy

Under UK data protection law (such as the UK GDPR), you need to balance security needs with privacy and compliance.

• Retain logs for a sufficient period (often 6 to 12 months) to support incident response and forensic investigations.

• Avoid keeping logs unnecessarily, especially if they contain personally identifiable information (PII).

• Regularly review your data retention policy in line with your risk profile and industry regulations (e.g., PCI DSS, ISO 27001).

6. Conduct Regular Threat Hunting

Go beyond alerts. Threat hunting involves proactively searching for indicators of compromise that may have slipped through.

• Use historical log data to look for stealthy behaviours, like lateral movement or persistence techniques.

• Correlate log data with known IOCs (Indicators of Compromise) from threat intelligence sources.

This proactive approach improves your chance of catching slow-burning or targeted attacks.

7. Test Your Logging and Detection

Finally, test the effectiveness of your logging strategy through:

• Red teaming / penetration testing

• Purple teaming (collaboration between offensive and defensive teams)

• Simulated attacks using tools like Atomic Red Team or MITRE Caldera

These exercises help you understand whether your logs would actually detect a real attack – and how quickly you’d respond.

Final Thoughts

Logs are more than just a compliance checkbox – they’re a crucial weapon in your cybersecurity arsenal. By collecting the right logs, centralising them, and actively analysing them for signs of threat activity, UK organisations can detect threats earlier, respond faster, and stay ahead of attackers.

If you haven’t reviewed your logging strategy recently, now’s the time. Because when it comes to cyber threats, what you don’t see can absolutely hurt you.

Need help with your log management or threat detection?