Tyepes of operating Module 4 chapter .pptx

Operation sysytem

1. Types of Operating Systems There are several types of operating systems, with Windows, Linux and Macintosh suites being the most widely used. Here is an overview on each system: Windows: Windows is the popular Microsoft brand preferred by most personal users.This system has come a long way from version 1.0 all the way up to the new Vista and soon to be released Windows 7. Although Windows has made strides in regard to security, it has a reputation for being one of the most vulnerable systems. Unix/Linux: The Unix operating system has been around for years, and it is well known for its stability. Unix is often used more as a server than a workstation. Linux was based on the Unix system, with the source code being a part of GNU open-source project. Both systems are very secure yet far more complex than Windows. Macintosh: Recent versions of the Macintosh operating system, including the Mac OS X, follow the secure architecture of Unix. Systems developed by Apple are efficient and easy to use, but can only function on Apple branded hardware.

2. Security Concerns The fact that an operating system is computer software makes it prone to error just as any human creation. Programmers make mistakes, and inefficient code is often implemented into programs even after testing. Some developers perform more thorough testing and generally produce more efficient software. Therefore, some operating systems and more error prone while others are more secure. Here are some common security issues that pose a threat to all operating systems: Instabilities and Crashes - Both of these instances may be the result of software bugs in the operating system. Bugs in software applications on the computer may also cause problems, such as preventing the system from communicating with hardware devices. They can even cause the system to become unstable or crash. A system crash consists of freezing and becoming unresponsive to point where the machine needs to be rebooted. These issues vary depending on the type of operating system. Flaws - Software bugs will not only make a system unstable, but also leave it wide open to unauthorized users. Once these vulnerabilities are discovered, attackers can exploit them and gain access to your system. From there, they can install malware, launch attacks on other machines or even take complete control of your system. Software developers usually distribute security patches rather quickly to update the operating system and fix the vulnerabilities. 2 2/19/2019

3. Protection and Security Protection is to provide mechanisms that prevent accidental or intentional misuse of a system. Three aspects to a protection mechanism: Authentication: identify a responsible party ( principal ) behind each action. Authorization: determine which principals are allowed to perform which actions. Access enforcement: combine authentication and authorization to control access. A tiny flaw in any of these areas can compromise the entire protection mechanism. 3 2/19/2019

4. Authentication How to do? Using password??? Identity of user…. Once you log in, your user id is associated with every process executed under that login: each process inherits the user id from its parent. 4 2/19/2019

5. A u t h o ri z ation Goal of authorization is…. Access Matrix is used to represent authorization information. Each entry of it shows what that principal can do to that object. Drawback of this approach? One row per principal. One column per object. Each entry indicates what that principle can do to that object. Access Control Lists (ACLs): organize by columns. With each object, store information about which users are allowed to perform which operations. Most general form: list of <user, privilege> pairs. Capabilities : organize by rows. With each user, indicate which objects may be accessed, and in what ways. Store a list of <object, privilege> pairs with each user. This is called a capability list . 5 2/19/2019

6. Access Enforcement Some part of the system must be responsible for enforcing access controls and protecting authentication and authorization info. 6 2/19/2019

7. Few common problems Trojan Horse: modify valid program to misbehave or steal information. Network attack: snoop on network traffic or other communications and steal unprotected information (e.g. passwords). Denial of service: create program that uses up all system resources to make system crash or prevent others from getting work done 7 2/19/2019

8. Some Attacks… Botnets and denial of service How to prevent your computer becoming part of a Botnet? Installing effective anti-malware software will help to protect your computer against Trojans and other threats. Kaspersky Lab has award-winning anti-malware solutions for:windows , apple macs and linux "Salami attack": checking account interest calculator that credited fractional cents to the account of the creator. A botnet is an interconnected network of computers infected with malware without the user's knowledge and controlled by cybercriminals. They're typically used to send spam emails, transmit viruses and engage in other acts of cybercrime. Sometimes known as a zombie army, botnets are often considered one of the biggest online threats today. The word Botnet is formed from the words ‘robot’ and ‘network’. Cybercriminals use special Trojan viruses to breach the security of several users’ computers, take control of each computer, and organize all of the infected machines into a network of ‘bots’ that the criminal can remotely manage. A salami attack is a small attack that can be repeated many times very efficiently. Thus the combined output of the attack is great. salami slicing/penny shaving where the attacker uses an online database to seize the information of customers, that is bank/credit card details, 8 2/19/2019

9. Some common Security Solutions Logging: record important actions and uses of privilege Principle of minimum privilege: limit access to only what is absolutely needed. Involve humans more: Auditing code to catch bugs and Trojan Horses. Human approval for particularly dangerous operations (e.g., large funds transfers) Prove correctness of system (absence of bugs) Information flow control : Control not only who can access what, but what they can do with the information once they have it. 9 2/19/2019

10. Clean up Activity Files That Need Computer Clean Up :There are a number of files that you want to include in a computer clean up to protect yourself against hackers that compromise your operating system with spyware so they can view your information. Browsing History: When you browse the Internet, your computer logs all of the websites you have visited. If these files are not deleted, anyone with unauthorized access your operating system can view your browsing history. Cookies: Cookies are files that originate from websites that you have visited. Every time you visit a website it installs a cookie into your PC that remembers your name, your shopping preferences, items of interest, and other information about you. Hackers often use cookies to find out sensitive information about you. Temporary Internet Files : Temporary Internet Files store a wide variety of information from websites that you visited.The information includes website pictures, links, sound files, and any other type of component from the website. All of these files are stored on your PC every time you visit a website.Temporary Internet Files are also known as a cache which can be viewed by anyone with unauthorized access to your PC's operating system. Documents: Microsoft Windows contains a feature that stores documents you recently worked on in the Start menu. Anyone who accesses your computer can view the files and if they contain sensitive information, this can present a problem. 10 2/19/2019