Reconstructing execution history from Windows disk artifacts

// Understanding Windows disk artifacts

Windows systems maintain various artifacts on disk that can help reconstruct user and system activity. This is particularly useful in forensic investigations to trace malicious actions or analyze user behavior.

Artifacts such as the Windows Registry, Event Logs, and file system metadata play a crucial role. Familiarity with these can significantly improve your investigation efficacy.

// Key Artifacts for Execution History

1. Windows Registry: The Registry is a hierarchical database that stores settings and options for the operating system and installed applications. Key hives to look at include: - HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run - HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall - HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Assist - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce

2. Event Logs: Windows logs various events which can indicate when applications were started or stopped. Use the Windows Event Viewer or PowerShell for extraction. - Look for Event IDs related to process creation, such as 4688 in the Security log.

3. File System Metadata: NTFS file system timestamps (created, modified, accessed) can provide insights into when files were executed or altered. Use NTFS tools to extract this data.

// Extracting and Analyzing Artifacts

Using PowerShell for Event Log Analysis

PowerShell offers powerful cmdlets for interacting with Windows Event Logs. The following command retrieves the last 50 process creation events:

Get-WinEvent -LogName Security | Where-Object { $_.Id -eq 4688 } | Select-Object -First 50

Each log entry will provide:

• TimeCreated: When the process was initiated.
• SubjectUserName: The user who created the process.
• NewProcessName: The path of the executable.

Registry Access via Command Line

You can extract relevant registry keys for analysis using the reg command:

reg query "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run" /s

This command will list all entries set to run on user login, providing insights into potential persistence mechanisms employed by malware.

File System Examination with FTK Imager

For file system metadata analysis, a tool like FTK Imager can be indispensable. It allows you to view and export file system structures while preserving original timestamps. The following checklist could guide your FTK Imager usage:

• Acquire the disk image: Use a write-blocker to ensure the original disk remains unaltered.
• Load the image: Open the acquired image in FTK Imager.
• Navigate to the relevant partitions: Look for the $MFT or specific user directories.
• Examine file timestamps: Check Created, Modified, and Accessed timestamps for executables.

Pitfalls to Avoid

• Ignoring User Assist: This registry key can reveal applications that users frequently execute, sometimes even outside typical access methods. Don't overlook this data.
• Overlooking the importance of Log Retention Policies: Ensure you understand the log retention policies of the systems you analyze, as older logs may be purged, leading to incomplete data.
• Neglecting alternate data streams: NTFS file systems allow data to be hidden in alternate streams, which could contain additional context about file usage.

// Conclusion

Understanding and reconstructing execution history from Windows disk artifacts is a multifaceted process that requires careful analysis of various data sources. By effectively leveraging the Windows Registry, Event Logs, and file system metadata, you can piece together a comprehensive view of user and system activities.

Utilizing these techniques in a controlled environment, such as a disposable lab range, can help solidify your skills without the ethical implications of unauthorized access.

--- // FIELDOPS REPORT AUTHORIZED BY: Rachel H. //