The Windows NT and Windows 2000 operating systems were designed from inception to be secure. Both enforce user logon and ensure that all software runs within the context of an account, which can be restricted or permitted appropriately. Windows security is not limited to user logon-based security, but extends to all objects within the operating system. Files on the hard drive, entries in the registry, software components?all these elements have a security aspect. Operating system components can access objects only with the appropriate permissions and credentials. This can be both a benefit and a detriment.
Enforcing security restrictions on every component of the operating system can seem daunting. Access checks must occur when one Windows component talks to another. These include programs, device drivers, core operating system components, and so on?in short, everything. Setting appropriate security permissions is a task that requires detailed knowledge of the subject and the interaction between the components being configured. Misconfiguration of these permissions could cause undesirable behavior ranging in severity from a minor and easily fixed problem to a complete and irreversible loss of functionality.
The fact that this daunting security environment is part of the fundamental design of Windows Server 2003 is a big advantage. If strong and pervasive security is not designed into the core of an operating system (for example, Windows 95), it is nearly impossible to add it later. Developers and testers may find holes or make compromises when they patch security into an operating system. Legitimate components may already be designed to take advantage of the lack of security. The environment would necessarily be less secure than one designed for security from the beginning.