Chapter#3 2Nd Term COMPUTER VIRUSES
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St. Francis’ High School Hayatabad Peshawar Computer Viruses Chapter#3 2nd Term COMPUTER VIRUSES Objective Type Questions 1. Choose the correct one. a) A computer virus may be capable of i. Infecting executable files ii. Infecting disks by attaching itself to special programs on the hard disk, called boot records iii. Both i and ii iv. None of the above b) Which of the following are the signs of a virus attack? i. The computer runs slower than normal ii. There is a change in file size iii. The computer restarts on its own iv. All of the above c) A computer virus can spread through i. Emails ii. USB iii. Both i and ii iv. None of the above Computer Science St. Francis’ High School Hayatabad Peshawar Computer Viruses d) Program viruses infect files that have the extension i. COM ii. EXE iii. SYS iv. All of the these e) Which of the following is a boot virus? i. Michelangelo ii. Sunday iii. Acid Rain iv. None of these f) Which of the following are infected by a macro virus? i. .exe file ii. Boot records iii. Data files iv. None of these g) ___________refers to computer programs that secretly gather information about the user and relay it to other interested parties i. Worm ii. Spyware iii. Virus iv. None of these Computer Science St. Francis’ High School Hayatabad Peshawar Computer Viruses h) ____________refers to unsolicited mail. i. Spam ii. E-mail iii. Mail iv. None of these Descriptive Type Questions 2. Answer the following. a) Name a type of virus that infects data files? Ans- Macro viruses: these infect data files, such as Word documents or Excel spreadsheets, rather than programs. MS Excel and MS Word files can get infected with Macro files as they allow the use of macros. Macro viruses are written using macro programming languages, designed to allow users to automate tasks within an application. b) What is the name given to a database of viruses that an antivirus software scans for? Ans- Virus definitions is the name given to a database of viruses. It is a file which is a combination of multiple files. It holds the information of different viruses and is used to identify a computer virus c) Define a computer virus. How can it harm your computer? Ans- A computer virus is defined as a computer program that has the ability to make copies of itself and, to attach itself to other programs or files. Viruses are written by expert computer programmers which can erase data or corrupt programs on the computer. Computer Science St. Francis’ High School Hayatabad Peshawar Computer Viruses Computer virus can harm a computer in different ways, in which few of the following is given below: It can infect executable program files such as word processors, spreadsheets, and operating systems. • It can infect disks by attaching itself to special programs on the hard disk, called boot records. • These are the programs that the computer uses to start itself up. • It can infect files that are attached to email messages or copied to disks and pen drives. In this manner, it can spread from one computer to another. d) Mention any three precautions you should take for protecting your computer from virus infections? Ans- Following are the three precautions that can be taken to protect our computer from the virus attack: i. Install and use antivirus software and keep it updated. ii. Never click on a link or attachment in an email, unless the email is from a trusted source. iii. Scan the files that you download from the internet. e) How does a computer virus spread from one computer to another? Ans: Computer viruses spread from one computer when a virus infected data is shared on a network or by the transfer through emails, USBs, a disk and file sharing methods. Once the virus is in the computer’s memory, it usually infects any program you run. f) Analyse how boot, macro, and program viruses affect the workings of your computer. Which in your opinion is more harmful? Give reasons for your answer? Computer Science St. Francis’ High School Hayatabad Peshawar Computer Viruses Ans- Boot Viruses Macro Viruses Program Viruses infect the boot records of both are written in the same infect program files and hard disks and floppy disks– language in which common become active when the they become active when the programs are written such as program is executed computer is ‘booted’, i.e. MS Excel or MS Word–they turned on. become active once the application is opened All viruses are harmful in their own way. In my opinion boot viruses are more harmful. Boot viruses are not very common in today’s life. But when it harms the computer it is more powerful because a boot sector virus can cause a variety of boot or data retrieval problems. In some cases, data disappear from entire partitions. In other cases, the computer suddenly becomes unstable. Often the infected computer fails to start up or to find the hard drive. While the Macro and program viruses harm the computer only when the programs and applications are opened, no doubt they are difficult to detect. g) McAfee virus scan and Microsoft security essential are two popular antivirus programs. Find out more about their features and justify why you would choose one over the other? Ans- McAfee Virus Scan Microsoft Security Essentials Freeware Freeware scans PC for viruses/spyware/malware scans PC for viruses/spyware/malware works in background works in background scans can be scheduled scans can be scheduled Computer Science St. Francis’ High School Hayatabad Peshawar Computer Viruses three alert options: immediate scan, cancel automatic updates which run every 24 hours; prescheduled scan, reschedule scan for later might need manual rescheduling if computer time usually off at time of updates 1MB in size 7MB in size does not clean malware does not clean malware I would like to choose Microsoft Security Essentials because it automatically updates which run every 24 hours, but if I will face the space problem in my computer system then most probably I will choose McAfee Virus Scan, because it only takes 1MB instead of 7 MB. Computer Science .