In this simulation, you will learn how to parse and interpret Windows Event Logs to identify unauthorized access. Mastering Event IDs is crucial for tracing the exact moments a threat actor successfully authenticates to a compromised system.
CHFI (312-49) Digital Forensics Simulation
Investigation Scenario
A Seattle-based financial firm suspected unauthorized data exfiltration via Remote Desktop Protocol (RDP) on a critical Windows Server 2019 instance (Hostname: FIN-SRV-01). The digital forensics team was deployed to preserve the evidence. A physical disk image was acquired using FTK Imager, and the resulting .E01 file was hashed and verified.
During the examination phase, the investigator mounted the image and focused on the operating system's native auditing artifacts to establish a timeline of access.
A preliminary extraction of the Security.evtx log reveals suspicious activity originating from an external IP address (198.51.100.44) between 02:00 and 02:15 AM local time.
TimeCreated Id LevelDisplayName Message
----------- -- ---------------- -------
10/24/2025 02:02:11 AM 4625 Information An account failed to log on.
10/24/2025 02:02:14 AM 4625 Information An account failed to log on.
10/24/2025 02:02:18 AM 4625 Information An account failed to log on.
... [14 identical events omitted] ...
10/24/2025 02:03:05 AM [???] Information An account was successfully logged on.
Question
During an investigation of a Windows-based server in Seattle, forensic examiners are looking for evidence of unauthorized remote access. They decide to analyze the Windows Event Logs for failed login attempts and remote desktop sessions. Which of the following Event ID numbers is typically associated with a successful logon?
Forensic Hint: Look at the chronological sequence in the evidence box. The failed attempts are ID 4625. In modern Windows auditing (Vista and later), the successful equivalent immediately precedes this number numerically.
Expert Analysis
What the evidence shows: The Security.evtx artifact demonstrates a brute-force attack (multiple 4625 events in rapid succession) followed immediately by a successful authentication event.
Forensic Stage: Examination & Analysis. The investigator has already collected the E01 image and is now parsing logical artifacts to answer the "who, what, when, and how."
Why the correct answer is correct: In the Windows Security Log, Event ID 4624 explicitly records that an account was successfully logged on. This event contains crucial metadata, including the Logon Type (e.g., Type 10 for RDP, Type 3 for Network) and the source IP address.
Why others are wrong:
4625: Indicates a failed logon attempt.
4634: Indicates an account was logged off, marking the end of a session.
4648: Indicates a logon was attempted using explicit credentials (often seen when running a process as another user, or using runas).
Real-world forensic action: An investigator would filter the Security.evtx file for Event ID 4624, specifically isolating Logon Type 10 (RemoteInteractive) to confirm RDP access. They would then correlate the generated Logon ID with the corresponding Event ID 4634 (Logoff) to determine the exact duration of the attacker's session.
MINI LESSON: Artifact Interpretation & Chain of Custody
When analyzing event logs, isolated events provide limited value. Forensic investigations require correlation. By pairing a 4624 (Logon) with a 4634 (Logoff) using the unique Logon ID assigned to that session, investigators can establish a strict timeframe for a suspect's activity. Furthermore, always ensure that log analysis is performed on an acquired image (like the E01 mentioned in the scenario) rather than the live system to maintain the integrity of the evidence and preserve the chain of custody.