Introduction to

Computer security

By, P.srinu 24

COMPUTER SECURITY

Why?:to protect the computing system and protect the data that they store and access Security attacks :- actions that

comprises the computer security Security mechanisms:-tools such

as algorithms, protocols designed to detect ,prevent or recover from a security attack

Security services :-specific kind of protection to the system resources

SECURITY THREAT

• Threat potential violation of security and also causes harm.• Vulnerability a weakness

that is left unprotected.

SECURITY ATTACKPassive attack:getting information from the

system ,but it does not affect the system. analyzing the traffic to find the nature of

communication difficult to detect as they do not involve

alteration of the data Hence better to Prevent rather than

Detection

Active Attack: tries to alter the system resources or affect its operations.

Masquerade replay(capture events and replay) Modifications of messages Denial of services

“Difficult to prevent but can be detected and recovered “

TARGET

users• identity• privacy of user

» eg.pin(personal identification number) of atm,credit card, login id’s, pass codes

How ?? tracking of users habits and actionsWhat??Cookies(cannot install malware) and spam mails are

used for attacking

Attacks on computer hardware• Natural calamities such as Floods,

Earthquakes, power fluctuations.• Destructive actions of burglars or people

Attacks on softwareAim? to harm the data stored and programs in

computer how??Executables files:- programs written to do harm

rather than goodWhat??malicious software :-a software code included

into the system which is harmful in natureHacking:-intruding into another computer or

network to perform an illegal act

MALICIOUS SOFTWARE

A software program which is Destructive in nature. Characteristics can attach itself to other healthy programs. replicates itself and thus can spread across a

network Infects an executable file or program Cannot infect write protect disks , hardware,

compressed files How dies it harm?

• Corrupt or delete data, change functionality of software , erase everything on the hard disk, degrade the system performance.

What?? E mail attachment, downloads on internet.

Eg. I love you, melissa,Brain, anna kournikova……….

VIRUS

Java scripts ,java applets and Activex controls

• Java applets :- it can be part of a web page and executed by the Java Virtual Machine executed by browsers for many platforms, including Microsoft Windows ,Unix, Linux etc.

• ActiveX controls:- similar to java applets but do not have security checks

• Java scripts:-a scripting language commonly implemented as part of a web browser in order to create enhanced user interfaces and dynamic websites

WORMS

• Self replicating software that uses network and security holes

• it scans the network of a system and copies itself and then starts replicating from there.

• Worm and virus are different

• Consumes the resources like bandwidth of computer and makes it slow.

E.g. nimda(multiple infectious virus), code red (Chinese),

TROJAN HORSE• It is a destructive program that

masquerade as useful program.

• The reason behind the name is the Greek soldiers who reached the city of troy by hiding in the wooden horse. Similarly games, software etc. can corrupt Data, Programs or damage files

???queries???