Network logs (specifically flow logs or NetFlow/IPFIX data) capture detailed information about network traffic, including source and destination IPs, ports used, protocols, and the volume of data transferred. This granularity is crucial for detecting subtle lateral movement. By analyzing these logs, you can identify unusual communication patterns between internal devices, deviations from established baselines, and suspicious port usage indicative of reconnaissance or exploitation activities.
You could use Wireshark and conduct a thorough PCAP analysis, for example.
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Firewall logs: While valuable for tracking allowed and denied connections at the network perimeter, firewall logs often lack the detailed inter-device communication within the internal network needed to detect lateral movement. They primarily focus on traffic crossing the firewall boundary.
Intrusion Detection System (IDS) logs: IDS logs are excellent for detecting known attack signatures and malicious activity. However, stealthy lateral movement often involves techniques that evade signature-based detection. While an IDS might catch some aspects of lateral movement, it's not the primary source for detecting subtle traffic pattern changes.
Security logs: These logs are essential for tracking user logins and access attempts. They can be helpful in identifying compromised accounts used for lateral movement. However, they don't directly provide the network traffic data (ports, protocols, communication patterns) needed to detect the movement itself. They show who might be moving, but not how they are moving across the network.