DFIR and Windows Event Logs

Digital forensics plays a critical role in modern incident response. Since most organizations rely upon Windows-based systems, Investigators must deep dive and interpret the system-generated artifacts that document user activity, security events, and administrative changes. Among these artifacts, the Windows Event Logs are a gold mine for structured sources of evidence. When examined carefully and within proper context, these logs reconstruct what the attacker did, identify other potentially compromised accounts, and assess the impact of the attacker’s activity.

When Incident response starts, the investigators and analysts operate under extreme time pressure to limit the incident’s impact, and in many cases digital forensics slows this down. Since many modern Security Incident and Event Management systems are extremely expensive, a workstations windows event logs may only be available on the local system. These logs are generated by the operating system itself and are difficult to falsify at scale without leaving secondary traces. These logs record authentication events, privilege assignments, process creation, and account management activity. Together, they form a framework for understanding how access occurred and how that access evolved during an incident.

Authentication is the foundation of nearly every intrusion investigation. An attacker may exploit a vulnerability, harvest credentials, or abuse misconfigurations, but continued access manifests as a logon event. Windows Event Logs has two helpful Event IDs. These are 4624 and 4625, which records successful and failed logon attempts respectively. These events reveal the account name, logon type, authentication mechanism, source workstation or IP address, and timestamp. When correlated across systems, they expose patterns such as brute-force attempts, credential stuffing, or lateral movement.

Event ID 4625 documents failed logons and often appears in large volumes during password attacks or with misconfigured services. Repeated failures against a single account may indicate a brute force attack, while failures across many accounts may indicate a password spraying attack. Event ID 4624 documents successful logons and carries even greater significance. A successful authentication using a privileged account from an unusual source or time may represent the moment an attacker achieves access. However, these events identify the account used, not the individual operating the keyboard. We must keep this in the back of our head.

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