When investigating suspected data theft, unauthorized access, or policy violations, network logs can be a goldmine of evidence. These records document the flow of data, system access, and connection attempts across your environment, often providing the missing link between device activity and account behavior.
The key is knowing which logs to collect, how to preserve them, and how to interpret them in the context of other forensic findings.
Why Network Logs Matter
Network logs can:
- Confirm or disprove claims about who accessed systems and when.
- Show the source and destination of data transfers.
- Highlight unusual patterns, such as large uploads, after-hours activity, or repeated failed logins.
- Corroborate evidence from computers, mobile devices, and cloud accounts.
Common Sources of Network Logs
- Firewall Logs: Track inbound and outbound traffic, blocked attempts, and policy rule matches.
- VPN Logs: Show remote access activity, including connection times, originating IPs, and device IDs.
- Switch and Router Logs: Record physical port usage, link changes, and MAC address activity.
- Intrusion Detection/Prevention Systems (IDS/IPS): Document suspicious or known-malicious traffic.
- Web Proxies: Log browsing activity and large file transfers.
Preservation Best Practices
- Identify relevant systems quickly and secure their log archives before they rotate or overwrite.
- Export logs in original formats with timestamps intact.
- Document the collection process for chain of custody.
- Align all timestamps to a common standard for cross-system analysis.
Interpreting Network Evidence
Network logs are most powerful when correlated with other artifacts. For example, firewall logs showing a large upload to a personal cloud service can be paired with endpoint evidence confirming the specific files transferred. This layered approach strengthens attribution and reduces ambiguity.
About Swailes Computer Forensics
Swailes Computer Forensics provides expert digital forensic services to law firms, corporations, and organizations nationwide. Our work includes investigations into intellectual property theft, employee misconduct, data breaches, and more. With decades of experience and a commitment to integrity and clarity, we help clients uncover critical evidence and take informed action. If you need to preserve or analyze network logs as part of an investigation, contact us for a consultation.