CBSE Book Class 11 Informatics Practices Information Security

Information Security and Social Networking

One day, Nalin received a strange email from his very good friend asking him to lend some money. In that mail his friend wrote that he is very far away from his place and has been trapped in some financial crisis. So he requested Nalin to transfer some amount of money to some specified bank. Nalin could not believe it and decided to first call up his friend and verify. And this was a wise thought as when he called up his friend he told him that everything is fine at his end. He also told Nalin that his email account password has been hacked by someone and now that person is sending the same mail to all the people in his contact list. This is just an example of cyber crime.

Crime has always been an unpleasant and unavoidable ingredient of our society. In the past couple of decades, computers and internet have dominated our society. We depend on computer and internet for communication, banking, finance, examination and many other serious matters. Computers have become virtual lockers used to store our secrets. Since computer is an essential and important part of our lives, crime cannot spare it too. Every day criminals evolve new methods to invade our virtual lockers or even our privacy created in or via computers. The crimes which involve computers are termed as cyber crimes. In this chapter, we focus on some of the common threats to a computer system and explain certain means of how one can deal with these threats.

Threats to a Computer System

Information security commonly refers to as CIA (short form of Confidentiality, Integrity and Authentication), protects our computer from any unauthorized access and maintains the system resources. Precisely,Confidentiality ensures protection of the computer system from any unauthorized access Integrity ensures that information stored in the computer is protected Authentication ensures the authenticity of the authorized user CIA can be weakened or broken in many ways. Some of the possible attacks are the following:

Viruses

Worms

Trojans

We will explain below these threats in details and possible measures to be taken to prevent these situations.

Viruses

Viruses are computer programs developed to copy themselves and infect other files stored on the computer. These are malicious programs that move from computer to computer by attaching themselves to files or boot records of disks and diskettes. Virus can automatically be transferred from one computer to another when its host is taken to the target computer, for example an user can sent it through a network or the internet, or carried it on a removable storage medium such as CD, DVD, USB pen drive or Memory

Cards.

Viruses can cause destruction to the entire file system which in result would need to reinstall and reload the whole system again. They can also create effected sectors on the disk destroying one or more files and part of some programs. Viruses also lesser the space on the hard disk by duplicating and attaching itself to various files. Through these viruses, system gets hang-up and the entire system stops working.

These days' viruses are spread through email attachments and other programs that can be downloaded from the internet. A virus acts like an agent that travels from one file to another on the same computer through an infected file.

The first ever virus named "Creeper" was first detected on ARPANET, in the early 1970s. It was an experimental self-replicating program written by Bob Thomas at BBN Technologies. Creeper infected some DEC PDP-10 computers running on the TENEX operating system. Via the ARPANET, Creeper copied itself to the remote systems where the following message was displaced:

"I'm the creeper, catch me if you can!"

To counter its effect, a program called "Reaper" was created.

Worms

It is a program made to replicate automatically. A worm replicates continuously until the entire hard disk space and memory are eaten up and it may do so without any user intervention. This kind of self replicating programs spread over the entire hard disk and memory consequently and slow down the system.

Unlike a virus, a worm does not need to attach itself to an existing executable program or code. Worms harm to a computer or a computer network by consuming bandwidth and slow down the network speed whereas viruses almost always corrupt or modify files on a targeted computer. After the worm has infected a system, it can propagate to other systems via internet or while copying files from one system to another without user interaction. The nasty result is a worm traversing through the Internet in a matter of hours, infecting numerous machines.

The destruction from a worm is less alarming than a virus in the sense that worm does not corrupt other files. It only eats up the memory.

Trojan

The term Trojan is derived from the Trojan Horse story in Greek mythology. Trojan horse is virtually a harmless program in itself. Like a virus or a worm, it neither corrupts other files on the system nor takes up the memory part. Nevertheless, the effect of a Trojan could be even more dangerous. In fact, at the backend, these programs perform some malicious activities like upload (send) some security files and information from the computer and at the same time download some unwanted files onto the computer. This way not only it slows own the network speed but also uploads (sends) some non shareable information to other computers like our user name, password, emails, credit card details and other secured information over the network. They are generally transferred by emails, attachments and freeware & shareware software.

Trojan horses are designed to allow a hacker to target a remote computer system. Once a Trojan horse has been installed on a target computer system, it is possible for a hacker to access it remotely and perform various operations and it may do so without any user intervention at the remote end.

There are many ways in which a Trojan Horse can propagate. The most common of them is through email attachments. Unintentionally, a user can download some Trojan from the internet as a freeware with the assumption of utility software. Other sources for Trojan horse are the chat software and email manager.

Please refer to the link below - CBSE Class 11 Informatics Practices Information Security