Windows System Files Every Cyber ​​Analyst Should Know

Windows System Files

Essential Knowledge for Cybersecurity and System Investigations

Windows is more than just a place to browse the internet or Shut Down your computer, It has many hidden features and secrets that most people don’t know about. Have you ever wondered where Windows stores your passwords? Or where does it keep DNS records? And when something goes wrong, how do experts find out what happened using log files?

In this blog, we’ll explore all these hidden parts of Windows. We’ll break down where this important data is stored and why it’s useful to know. By the end, you’ll have a clearer understanding of how Windows works behind the scenes.

C:\Windows\System32\drivers\etc\hosts

This file is a crucial part of Windows. It’s like a local map that tells your computer where to find certain websites or servers. Before your system checks the DNS (Domain Name System) on the internet to find the IP address of a website, it first looks at this file to see if there’s already an entry for that site.

For example, if you add a line in the `hosts` file like:
xxx.xx1 example.com

This tells your computer that whenever you try to visit “example.com“, it should redirect you to the IP address “xxx.xx1” which is the address for your local machine. This can be useful for blocking websites, testing websites before they go live, or redirecting domains for specific purposes.

Remember, editing the `hosts` file requires Administrative Privilegesand it should be done with care since incorrect entries could affect your ability to access websites properly.

C:\Windows\System32\config\SAM

This file is one of the most critical and sensitive files in the Windows operating system. SAM stands for ‘Security Account Manager’. This file stores user account information, including the hashed passwords for every user on the system.

Because of the sensitive nature of the data stored in the SAM file , It is heavily protected by Windows. The file is locked by the system, meaning you can’t simply open or edit it while Windows is running. This security measure helps prevent unauthorized access to user credentials.

Even though the passwords in the SAM file are hashed (which means they are stored in an encrypted format), the file is still a prime target for attackers looking to gain control of a system. This is why understanding and securing the SAM file is essential for maintaining the security of your Windows system.

C:\Windows\System32\repair\SAM

This file is a Backup Copy of the main SAM file found in the `Config` directory. This backup is created during the installation of Windows and can be used to restore the original SAM file in case it gets corrupted or damaged.

The `repair` folder contains backups of critical system files, and the `SAM` file in this directory can be vital for system recovery. However, since this backup is usually created during the initial setup of Windows, it may not contain any updates or changes made to user accounts after installation.

Just like the main SAM filethis backup should be handled with extreme caution, as it also contains hashed passwords and sensitive user account information. However, unlike the active SAM file in the `config` directory, this one can be accessed without the system locking it, making it easier to retrieve for recovery purposes.

C:\Windows\System32\config

This directory contains several critical files that are part of the Windows Registry. These files include `SYSTEM`, `SECURITY`, and `SOFTWARE`, among others. Each of these files stores essential system settings and configurations that Windows relies on to operate properly.

These files are critical for the operation of Windows, and any corruption or unauthorized modification can lead to serious system instability or even render the system unbootable. They are typically accessed and modified only by the operating system, although advanced users and administrators may interact with them via the Registry Editor or during recovery operations.

C:\Windows\System32\config\SYSTEM

The `SYSTEM` file contains information about the computer’s hardware and the system configuration, such as the drivers and services that should be loaded at startup. It’s a vital part of the Windows Registry‘s `HKEY_LOCAL_MACHINE\SYSTEM` hive, which includes settings related to the Windows boot process, hardware profiles, and control sets.

C:\Windows\System32\config\SECURITY

The `SECURITY` file stores security-related information and policies, including details about user rights, security policies, and auditing settings. It corresponds to the `HKEY_LOCAL_MACHINE\SECURITY` hive in the Registry and is crucial for enforcing security policies on the system.

C:\Windows\System32\config\SOFTWARE

The `SOFTWARE` file contains information about the installed applications and system components. This file is associated with the `HKEY_LOCAL_MACHINE\SOFTWARE` hive, where you can find settings related to both the operating system and third-party software, including application configurations, licensing information, and system-wide settings.

C:\Windows\System32\winevt

directory stores Windows event logs, which are detailed records of system, application, and security activities. These logs, saved in .evtx files, track events like program starts, errors, and login attempts. For cyber analysts, this directory is crucial as it provides a comprehensive history of system activities, helping in troubleshooting issues and detecting suspicious behavior by reviewing the logs with tools like the Event Viewer.

C:\Windows\WindowsUpdate.log

The WindowsUpdate.log file is a log file that records the details of the Windows Update process. It contains information about updates that have been installed or attempted, including success and failure messages, error codes, and other relevant details. This file is essential for troubleshooting Windows Update issues, as it provides a comprehensive record of update activities on the system.

While not as sensitive as files like the SAM file, the WindowsUpdate.log can be valuable for IT professionals and system administrators to diagnose and resolve update-related problems. By analyzing the contents of this log, one can identify patterns or specific errors that might be preventing updates from installing correctly. However, due to its detailed nature, it can also reveal insights into the system’s configuration and update history, making it a useful tool for maintaining and optimizing the Windows operating system.

The file is not locked by the system, so it can be opened and reviewed by anyone with appropriate permissions on the system. However, it is generally read-only by standard users, with modifications typically limited to administrative processes.

Understanding these directories helps in locating important files, logs, and configurations that might be targeted or altered during a cyber attack. It also aids in tracing the activities of users and applications, identifying malicious software, and determining the persistence mechanisms employed by attackers.

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