Class 11 Computer Science Chapter 6 Notes

• Define Security ? Describe the means to give access to authorized persons.
• Describe the means through which virus propagates (reaches from one computer to the other).
• Describe important types of viruses.
• Describe the ways, How to safe guard against viruses.
• Explain Data Security.
• Describe the ways the Data Security may be violated.
• Describe the main threats to Data Security.
• Describe Data Protection.
• Describe Data Privacy Issue.
• Describe the points necessary to ensure Individual’s Privacy.
• Define Data Protection Legislation? and state principles of Data Protection Act.
• Describe various Important Privacy Acts.
• Causes of Viruses: Following are the means through which a virus reaches from one computer to another.
• Email: Now a days, most of the virus programs spread by attaching themselves with email messages. When a user opens such an infected message, the virus is also loaded into the computers memory and attaches copies of itself with many files. Then this virus gets itself attached with email message sent from the infected computer and infects other computers.
• Networks: Another way of spreading virus is by using Internet and other networks. For example when you download some executable file or data from the Internet or from a shared disk on the Network, the infected files may be attached with the downloaded data that ultimately infects the computer.
• Removable storage media: One important means of exchanging data is through the use of removable media like memory cards CDs and flash devices. So, when you copy the data from one computer to another by using a removable media, the infected files may get transferred.
• Pirated Software: Another important but not so common way the virus infects your computer is through the use of pirated software. Some companies may intentionally put some virus program into their software. This program will only activate when it does not find some special files like license files on your computer.
• Types of Virus :Following are some important types of viruses:
• Boot sector virus: We know that the disk is divided into tracks and sectors. The disk on which the operating system has been loaded, has a special program in its first sector called the boot sector. When the computer is turned on, the program in the boot sector is automatically loaded into the memory. This program then loads the operating system into the memory after performing some initial tasks. The boot sector virus modifies the program in the boot sector and is loaded into memory whenever computer is turned on. The virus is attached with the executable files i.e. .exe, .com an .dll files. When the user uses these executable files, the virus attached with these files is also activated and then it infects other files and also performs destructive commands and destroys the data files also. Chernobal Virus: The famous chernobal virus deletes all the Microsoft office files and also the partition information form the disk hence causing a major loss of data. Logic bomb: Logic bomb, differ from other viruses in that they are set to go off at a certain date and time. A disgruntled programmer, for a defense contractor created a bomb in a program that was supposed to go off two months after he left. Designed to erase in inventory tracking system, the bomb was discovered only by chance.