Computer Security

•INTRODUCTION 

We use computers for performing several tasks like preparing documents, processing data, preparing financial reports, handling accounts, transferring information, online shopping, online transaction, etc. The documents, financial reports, data, information, etc. are valuable to organizations, companies, offices or people. The programs that are used for performing different tasks are also valuable to the organizations, in a companies, offices or people. The loss or damage of these documents, reports, data and information can cause serious damage to the organizations, offices, companies Or or people. So, we need to protect data, information and programs from malicious codes. We also need to keep computer systems secured from the physical factors like power fluctuation, power failure, dusts, hackers and thieves. Sometime a person can rms also delete data, information or programs accidentally. If we do not apply security and measures then computer system can be damaged or lost at any time.

A computer system is needed to secure from accidental or intentional harm. The protection of computer system from being lost or damaged due to accidental or intentional harm is known as computer security. In other words, computer security is the protection of computer data, information, programs and hardware from malicious attackers and accidental harm as well as to keep the computer system in good working condition. Computer security is also known as cyber security or IT security. Computer security involves the controlling accessing of computer system as well as protecting against the harm that occurs via network access, data and code injection.

• SECURITY THREATS TO COMPUTER SYSTEMS

The security threat to computer system is anything that causes to loss or corruption of data, Information, software or physical damage to the computer hardware. Simply we can defined computer security threat as anything that has potential to cause harm to data, Information, software and hardware. It affects the smooth functioning of a computer. The security threats may be physical threats or non-physical threats.

A physical threat refers to anything that has the potential to lead loss or corruption of data or physical damage to the computer system accidentally or intentionally. The physical threats include fire, high voltage, power failure/fluctuation, faulty wiring, theft, etc. Stealing a computer that contains vital data, information or software is physical threat. Damaging data, software or hardware due to frequent power failure, fire, and high voltage or over heat are the physical threats.

A non-physical threat is a potential cause to loss or corruption of data, information or software of a computer system intentionally. The non-physical threat is also known as logical threat. The non-physical threats include malicious codes and unauthorized access.

•MALICIOUS CODES

Malicious code is the harmful computer code or website script that is intended to cause undesired effects, security breaches or damage to a computer system. It is unwanted files or programs that can cause harm to data, information or software of a computer. Malicious code can cause deleting document files, email files or passwords; corrupting data, information or programs; reformatting hard drives; overloading network and mail servers and stealing data, information and passwords.

Malicious code includes computer viruses, worms, Trojan horses, malicious websit scriptsand other malicious active contents.

_______________________________________Fact:- Malware refers to malicious software, but malicious code includes website scripts that can exploit vulnerabilities in order to upload malware.

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•Computer Virus

Computer virus is a man-made destructive program that disturbs the normal functioning of a computer by loading unnecessary programs, deleting files (data file or program files), altering content of files, corrupting files, stealing information, etc. It is designed intentionally to harm data, information and programs of the computer. Computer viruses hide themselves in other host files and replicate themselves. When a virus infected file or program is used, the virus becomes active and performs its destructive tasks.

Destructive tasks of computer viruses: The common destructive tasks of computer viruses are as follow:

a. Computer virus can degrade the overall performance of the computer system.

b. Computer virus can replicate and spread from one file to other files or from one computer to other computers.

c. Computer virus can change the content of the files and codes of programs. d. Computer virus can delete, steal and destroy data, information and programs.

e. Computer virus can even destroy file allocation table (FAT) of a disk and files

become inaccessible.

f. Computer virus can run unwanted programs and occupy a large volume of memory space so other programs cannot run due to insufficient available memory space. g. Computer virus can display unnecessary messages and pictures.

•Spreading of computer viruses

When a virus infected file or program file is transferred from a computer to other computers, the other computers also get infected by computer virus. Computer viruses can spread from one computer to other computers through the following ways:

a. By sharing of infected portable storage device

 When you share virus infected portable storage device like external hard disk optical disk or pen drive, viruses of the storage device can transfer to othe disk.

b. By using pirated software

       The pirated software is developed in order to earn money illegally. So, the person or company involved in making pirated software does not apply any security measure to stop viruses to be copied. That means a pirated software may contain viruses and when such virus infected pirated software is used computer get infected with viruses. the

c. By opening viruses infected email or attached files 

Asuspicious email or attached file may have viruses. When you open such email or attached file, viruses can transfer to a computer.

d. By downloading files from unreliable web sites.

 There are many different web sites on the Internet. Some web sites on the Internet are designed for bad purpose like stealing data, information and spreading viruses. When you browse and download files from such web site viruses may transfer to your computer along with files.

e. By exchanging of date, information or files on the network.

 When computers are on the network they can share data, information a files. A file of one computer can be transferred to other computers. When one computer on the network is infected with viruses, there is high chance spreading viruses on other computers.

•Symptoms of Computer Viruses

You may find the following symptoms, if a computer is infected with viruses:

a. Changes in the size of files or executable files.

b. Opening of the program takes more time or fails to open.

c. Programs hang frequently or restart automatically. d. Missing of files or appearing of unexpected files.

e. Appearing of low memory message frequently.

f. Accessing of optical drive or floppy disk drive occurs frequently without any instruction.

g. Appearing of unusual error messages.

Protection from Computer Viruses

Computer viruses are harmful to a computer system. They can damage data, information, program files and due to which computers cannot perform tasks properly. So, the computer system must be protected from computer viruses. The computer system can be protected from the computer viruses by the following preventive measures:

a. Install antivirus software and update the virus definition file frequently. b. Install the firewall.

C. Install the latest security patch program. d. Scan the computer for viruses regularly.

e. Scan the portable disk like optical disk, pen drive, etc. for viruses before

opening the contents of the portable disk. f. Stop using pirated software.

g. Do not download files from the web sites without confirming they are free

from viruses.

h. Do not open suspicious e-mail and attachments.

i. Apply password for to prevent the computer system from being used by others.