1. SYSTEM SECURITY & ANTIVIRUS Chapter - 5 12015-2016 Dr. BALAMURUGAN MUTHURAMAN

2. The meaning of the term computer security has evolved in recent years. Before the problem of data security became widely publicized in the media, most people’s idea of computer security focused on the physical machine. Traditionally, computer facilities have been physically protected for three reasons.  To prevent theft of or damage to the hardware  To prevent theft of or damage to the information  To prevent disruption of service Strict procedures for access to the machine room are used by most organizations, and these procedures are often an organization’s only obvious computer security measures. Today, however, with pervasive remote terminal access, communications, and networking, physical measures rarely provide meaningful protection for either the information or the service; only the hardware is secure. M EANING OF C OMPUTER SECURITY 22015-2016

3. Today, however, with pervasive remote terminal access, communications, and networking, physical measures rarely provide meaningful protection for either the information or the service; only the hardware is secure. Most computer facilities continue to protect their physical machine far better than they do their data, even when the value of the data is several times greater than the value of the hardware. Despite significant advances in the state of the art of computer security in recent years, information in computers is more vulnerable than ever. Each major technological advance in computing raises new security threats that require new security solutions, and technology moves faster than the rate at which such solutions can be developed. 32015-2016

4. VIRUS A virus is software that spreads from program to program, or from disk to disk, and uses each infected program or disk to make copies of itself. Basically computer damage. 42015-2016

5. The term comes from biology. A computer virus reproduces by making, possibly modified, copies of itself in the computer’s memory, storage, or over a network. Similar to the way a biological virus would work. The very first virus to be created outside the single computer or lab was the program called "Elk Cloner.” It was written by Rich Skrenta in 1982. The virus attached itself to the Apple DOS 3.3 operating system and spread through floppy disk. The virus was originally a joke, created by a high school student and put onto a game. The 50 th time someone played the game, the virus would be released. So instead of playing the game, the user saw a blank screen that read a poem about the virus named Elk Cloner. 52015-2016

6. A VIRUS SPREAD First a programmer writes the virus most often being attached to a normal program; unknown to the user, the virus spreads to other software. Then the virus is passed by disk or network to other users who use other computers. The virus then remains hidden as it is passed on. 62015-2016

7. TYPES OF VIRUSES The way viruses are usually categorized is by what they do.  The boot virus which infects the boot sector of disk storage  The program virus which infects the executable programs  The multipartite virus which is a combination of the boot and program virus  The stealth virus which is able avoid detection by a variety of means such as removing itself from the system registry, or hidden as a system file  The parasitic virus which inserts itself into another file or program such that the original file is still workable  The polymorphic virus which changes its code structure to avoid detection and removal  The macro virus which exploits the macro language of a program like Microsoft Word or Excel. 72015-2016

8. TO PROTECT THE SYSTEM Run a more secure operating system like UNIX, another computer operating system in which you never hear about viruses on these operating systems because the of the security features If you are using an unsecured operating system, you can buy virus protection software like McAfee or Norton AntiVirus To help avoid viruses, it is very important that your computer is current with the latest update and antivirus tools, try to stay informed with recent threats about viruses and that you be careful when surfing the Internet, downloading files and opening attachments 82015-2016

9. WORMS Worms have been around since 1988. A computer worm is very similar to that of a normal computer virus. Unlike a virus though, the worm is a program that can copy itself across a network and it can run on itself. A worm also has a unique feature in the sense it does not have to host program in order to run. A worm works by copying itself into nodes or network terminals which does not require any intervention from the user itself. Worms began to take off in the late ‘90s and early 2000’s. These modern worms ran themselves through the internet and many file sharing programs such as KaZaa, a music file-sharing program. 92015-2016

10. TYPES OF WORMS The “Email Worm” – The email worm spreads itself through email – The worm can hide itself in messages as a link or an attachment that will redirect the user to an infected website. – Many users become losses to this particular worm due to their weakness and willingness to read and open messages that they think could be interesting. The Instant Messaging Worm – This worm masks itself in the form of an “IM” with the contents of a link that will redirect the user to an infected website and then try to gain full access of the machine. 102015-2016

11. PROTECT YOURSELVES Even though it seems impossible to not catch a worm, it is not. One of the best things a computer owner can do is install and run anti-virus software, especially the kind that updates automatically. Anti-virus software will notify the user when a virus or worm is found and prevent it from running and/or copying itself. Other precautions to protect in worm  Choosing secure passwords and changing them regularly  Not opening unfamiliar emails or attachments and most importantly not running or copying software from an unsecured website. 112015-2016

12. VIRUSES VS WORMS 1.Spreads from program to program, or from disk to disk 2.Uses each infected program or disk to make copies of itself 3.Computer damage 4.Destroys data or erases disks 5.Operating system specific 1. Uses computer hosts to reproduce themselves 2. Travel independently over computer networks 3. Software sabotage 4. Resides in memory rather on disk 5. Puts computers at a standstill 122015-2016

13. ANTIVIRUS SOFTWARE Computer programs intended to identify and eliminate computer viruses. 132015-2016

14.  The most widely used software is the Norton Antivirus. (NAV)  Since its release in 1990, over 100 million people around the world have used it.  It is a free program but in order to receive live updates, a valid subscription is needed. 142015-2016

15.  McAfee Virus Scan is another popular antivirus program.  It’s designed for home and home-office use.  It’s used specifically on a Microsoft Windows platform.  The latest edition includes a number of features including on access file sharing, inbound and outbound firewall protection, and daily definition updates. 152015-2016

16.  For the average home user and advanced users the Kaspersky antivirus software has an easy to use interface.  The program uses 3 tabs for protection, settings and support.  It updates itself on an hourly basis and is one of the fastest antivirus programs available. 162015-2016

17. ANTIVIRUS SOFTWARE: HOW IT WORKS “Antivirus software is the equivalent to penicillin of the computer world.” Like penicillin, antivirus applications act as a protector over your system, scanning incoming files and applications, “quarantining” or cleaning up unwanted viruses looking to cause harm to your system. Antivirus software is considered to be an aid that detects, fixes and even prevents viruses and worms from spreading to your computer as well as connecting computers. 172015-2016

18. DRAWBACKS OF ANTIVIRUS SOFTWARE  Some antivirus software can considerably reduce performance.  There should not be more than one antivirus software installed on a single computer at any given time.  It is sometimes necessary to temporarily disable virus protection when installing major updates.  Some argue that antivirus software often delivers more pain than value to end users. 182015-2016

19. TWO MAIN TYPES OF ANTIVIRUS There are different types of antivirus software for different computers. Some are designed for personal computers. Some are for servers and others for enterprises. There are mainly two types of antivirus software are Specific Scanning and Generic Scanning 192015-2016

20. SPECIFIC SCANNING Specific scanning also called signature detection The application scans files to look for known viruses matching definitions in a “virus dictionary” then it takes necessary action The specific scanning is not always reliable because virus authors are creating new ways of masking their viruses so the antivirus software does not match the virus signature to the virus dictionary. 202015-2016

21. GENERIC SCANNING Generic scanning is also referred to as the suspicious behavior approach. Generic Scanning is used when new viruses appear. In this method the software does not look for a specific signature but instead monitors the behavior of all applications. If anything questionable is found by the software the application is quarantined and a warning is broadcasted to the user about what the program may be trying to do. 212015-2016

22. Computer viruses and worms can so easily be placed into your work station and you must be careful when going on the internet, opening emails from unknown users, make sure you have some kind of anti-virus software and always get updates then only you are not helping to spread viruses and worms to other people as well as harming yourself and your pocket. 222015-2016