Question

Write 400–600 words that respond to the following questions: Distinguish Operating System (OS) component from architecture. Describe the basic Windows OS architecture. Discuss access control and authorization. Summarize the principles of least privilege. Differentiate among identification, authentication, and authorization. Describe Microsoft Windows access permissions.

Answer 1

Distinguish Operating System (OS) component from architecture =>

An operating system provide interface between user and hardware,

The kernel is the core of an operating system. It is the software responsible for running programs and providing secure access to the machine's hardware. Since there are many programs, and resources are limited, the kernel also decides when and how long a program should run. This is called scheduling. Accessing the hardware directly can be very complex, since there are many different hardware designs for the same type of component. Kernels usually implement some level of hardware abstraction (a set of instructions universal to all devices of a certain type) to hide the underlying complexity from applications and provide a clean and uniform interface. This helps application programmers to develop programs without having to know how to program for specific devices. The kernel relies upon software drivers that translate the generic command into instructions specific to that device.

An operating system kernel is not strictly needed to run a computer. Programs can be directly loaded and executed on the "bare metal" machine, provided that the authors of those programs are willing to do without any hardware abstraction or operating system support. This was the normal operating method of many early computers, which were reset and reloaded between the running of different programs. Eventually, small ancillary programs such as program loaders and debuggers were typically left in-core between runs, or loaded from read-only memory. As these were developed, they formed the basis of what became early operating system kernels. The "bare metal" approach is still used today on many video game consoles and embedded systems, but in general, newer systems use kernels and operating systems.

Four broad categories of kernels:

• Monolithic kernels provide rich and powerful abstractions of the underlying hardware.
• Microkernels provide a small set of simple hardware abstractions and use applications called servers to provide more functionality.
• Exokernels provide minimal abstractions, allowing low-level hardware access. In exokernel systems, library operating systems provide the abstractions typically present in monolithic kernels.
• Hybrid (modified microkernels) are much like pure microkernels, except that they include some additional code in kernelspace to increase performance.

History of monolithic operating system

The monolithic operating system is also known as the monolithic kernel. This is an old type of operating system. They were used to perform small tasks like batch processing, time sharing tasks in banks. Monolithic kernel acts as a virtual machine which controls all hardware parts. It is different than microkernel which has limited tasks. A microkernel is divided into two parts i.e. kernel space and user space. Both these parts communicate with each other through IPC (Inter-process communication). Microkernel advantage is that if one server fails then other server takes control of it. Operating systems which use monolithic architecture were first time used in the 1970’s.

Features of the monolithic operating system

Simple structure:

This type of operating system has a simple structure. All the components needed for processing are embedded into the kernel.

Works for smaller tasks:

It works better for performing smaller tasks as it can handle limited resources.

Communication between components:

All the components can directly communicate with each other and also with the kernel.

Fast operating system:

The code to make monolithic kernel is very fast and robust.

Limitations of a monolithic operating system

• Code written in this operating system (OS) is difficult to port.
• Monolithic OS has more tendency to generate errors and bugs. The reason is that user processes use same address locations as the kernel.
• Adding and removing features from monolithic OS is very difficult. All the code needs to be rewritten and recompiled to add or remove any feature.

Examples of monolithic operating system

• VMS
• Linux
• OS/360
• OpenVMS
• Multics
• AIX
• BSD

The basic Windows OS architecture =>

The architecture of Windows NT, a line of operating systems produced and sold by Microsoft, is a layered design that consists of two main components, user mode and kernel mode. It is a preemptive, reentrant operating system, which has been designed to work with uniprocessor and symmetrical multiprocessor (SMP)-based computers. To process input/output (I/O) requests, they use packet-driven I/O, which utilizes I/O request packets (IRPs) and asynchronous I/O. Starting with Windows XP, Microsoft began making 64-bit versions of Windows available; before this, these operating systems only existed in 32-bit versions.

Programs and subsystems in user mode are limited in terms of to what system resources they have access, while the kernel mode has unrestricted access to the system memory and external devices. Kernel mode in Windows NT has full access to the hardware and system resources of the computer. The Windows NT kernel is known as a hybrid kernel. The architecture comprises a simple kernel, hardware abstraction layer (HAL), drivers, and a range of services (collectively named Executive), which all exist in kernel mode.^[1]

User mode in Windows NT is made of subsystems capable of passing I/O requests to the appropriate kernel mode device drivers by using the I/O manager. The user mode layer of Windows NT is made up of the "Environment subsystems", which run applications written for many different types of operating systems, and the "Integral subsystem", which operates system-specific functions on behalf of environment subsystems. The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to.

Access control and authorization. Summarize the principles of least privilege =>

The principle of least privilege (POLP), an important concept in computer security, is the practice of limiting access rights for users to the bare minimum permissions they need to perform their work. Under POLP, users are granted permission to read, write or execute only the files or resources they need to do their jobs: In other words, the least amount of privilege necessary.

Additionally, the principle of least privilege can be applied to restricting access rights for applications, systems, processes and devices to only those permissions required to perform authorized activities.

Depending on the system, some privilege assignments may be based on attributes that are role-based, such as business units like marketing, human resources or IT, in addition to other parameters such as location, seniority, special circumstances or time of day. Depending on the operating system in use, administrators may need to tailor the different default privilege settings available for different types of user accounts.

Superuser accounts, mainly used for administration by IT staff members, have unlimited privileges over a system. The privileges granted to superuser accounts include full read, write and execute privileges as well as the ability to make changes across a network, e.g., installing or creating software or files, modifying settings and files, and deleting data and users.

Under current best practices for security, access through superuser accounts should be limited to only those required to administer systems; ideally, superuser credentials should never be used to log in to an account, but rather used with the "sudo" ("superuser do") command in Unix/Linux systems, which allows the holder of superuser credentials to issue a single command that is executed with superuser privileges. This reduces the risk of an active superuser session being hijacked.

Applying the principle of least privilege to standard user accounts means granting a limited set of privileges -- just enough privileges for users to get their jobs done, but no more than that. This type of account should be the template for ordinary employees -- least privileged users (LPUs) -- who do not need to manage or administer systems or network resources. These are the type of accounts that most users should be operating the majority of the time.

Why the principle of least privilege is used

As an essential aspect of IT security, the principle of least privilege is one of the most important security policies enterprises must enforce. It is designed to improve the protection of data and functionality from faults, i.e., fault tolerance, as well as from malicious behavior. Organizations that follow the principle of least privilege ensure that users don't have more access to systems and data than they need to do their jobs.

For example, an HR staffer may need read and write access to the enterprise payroll database, but that same employee would have no need to access the enterprise client database; at the same time, an employee in the sales department would need access to the client database, but would be denied access to the payroll database.

Ensuring that employees are assigned the correct privileges prevents giving employees access to systems they don't need while also preventing malicious workers from accessing systems or data outside of their job functions. In addition, if an employee's credentials are compromised, the thief can only gain that employee's privileges.

Differentiate among identification, authentication, and authorization =>

Both the terms are often used in conjunction with each other in terms of security, especially when it comes to gaining access to the system. Both are very crucial topics often associated with the web as key pieces of its service infrastructure. However, both the terms are very different with totally different concepts. While it’s true that they are often used in the same context with the same tool, they are completely distinct from each other.

Authentication means confirming your own identity, while authorization means granting access to the system. In simple terms, authentication is the process of verifying who you are, while authorization is the process of verifying what you have access to.

Authentication

Authentication is about validating your credentials like User Name/User ID and password to verify your identity. The system determines whether you are what you say you are using your credentials. In public and private networks, the system authenticates the user identity via login passwords. Authentication is usually done by a username and password, and sometimes in conjunction with factors of authentication, which refers to the various ways to be authenticated.

Authentication factors determine the various elements the system use to verify one’s identity prior to granting him access to anything from accessing a file to requesting a bank transaction. A user’s identity can be determined by what he knows, what he has, or what he is. When it comes to security, at least two or all the three authentication factors must be verified in order to grant someone access to the system.

Based on the security level, authentication factor can vary from one of the following:

• Single-Factor Authentication – It’s the simplest authentication method which commonly relies on a simple password to grant user access to a particular system such as a website or a network. The person can request access to the system using only one of the credentials to verify his identity. The most common example of a single-factor authentication would be login credentials which only require a password against a username.
• Two-Factor Authentication – As the name suggests, it’s a two-step verification process which not only requires a username and password, but also something only the user knows, to ensure an additional level of security, such as an ATM pin, which only the user knows. Using a username and password along with an additional piece of confidential information makes it virtually impossible for fraudsters to steal valuable data.
• Multi-Factor Authentication – It’s the most advanced method of authentication which uses two or more levels of security from independent categories of authentication to grant user access to the system. All the factors should be independent of each other to eliminate any vulnerability in the system. Financial organizations, banks, and law enforcement agencies use multiple-factor authentication to safeguard their data and applications from potential threats.

For example, when you enter your ATM card into the ATM machine, the machine asks you to enter your pin. After you enter the pin correctly, the bank then confirms your identity that the card really belongs to you and you’re the rightful owner of the card. By validating your ATM card pin, the bank actually verifies your identity, which is called authentication. It merely identifies who you are, nothing else.

Authorization

Authorization, on the other hand, occurs after your identity is successfully authenticated by the system, which ultimately gives you full permission to access the resources such as information, files, databases, funds, locations, almost anything. In simple terms, authorization determines your ability to access the system and up to what extent. Once your identity is verified by the system after successful authentication, you are then authorized to access the resources of the system.

Authorization is the process to determine whether the authenticated user has access to the particular resources. It verifies your rights to grant you access to resources such as information, databases, files, etc. Authorization usually comes after authentication which confirms your privileges to perform. In simple terms, it’s like giving someone official permission to do something or anything.

For example, the process of verifying and confirming employees ID and passwords in an organization is called authentication, but determining which employee has access to which floor is called authorization. Let’s say you are traveling and you’re about to board a flight. When you show your ticket and some identification before checking in, you receive a boarding pass which confirms that the airport authority has authenticated your identity. But that’s not it. A flight attendant must authorize you to board the flight you’re supposed to be flying on, allowing you access to the inside of the plane and its resources.

Access to a system is protected by both authentication and authorization. Any attempt to access the system might be authenticated by entering valid credentials, but it can only be accepted after successful authorization. If the attempt is authenticated but not authorized, the system will deny access to the system.

Authentication	Authorization
Authentication confirms your identity to grant access to the system.	Authorization determines whether you are authorized to access the resources.
It is the process of validating user credentials to gain user access.	It is the process of verifying whether access is allowed or not.
It determines whether user is what he claims to be.	It determines what user can and cannot access.
Authentication usually requires a username and a password.	Authentication factors required for authorization may vary, depending on the security level.
Authentication is the first step of authorization so always comes first.	Authorization is done after successful authentication.
For example, students of a particular university are required to authenticate themselves before accessing the student link of the university’s official website. This is called authentication.	For example, authorization determines exactly what information the students are authorized to access on the university website after successful authentication

Microsoft Windows access permissions =>

access control refers to security features that control who can access resources in the operating system. Applications call access control functions to set who can access specific resources or control access to resources provided by the application.

This overview describes the security model for controlling access to Windows objects, such as files, and for controlling access to administrative functions, such as setting the system time or auditing user actions. The Access Control Model topic provides a high-level description of the parts of access control and how they interact with each other.