INTRODUCTION TO COMPUTER & NETWORK SECURITY

INTRODUCTION TO COMPUTER & NETWORK SECURITY Instructor: Dania Alomar

Why Study Security ? • Security threats are real… • And need protection against • Keeping information secure from modification and unauthorizedaccess. • Keeping it available is getting increasingly difficult.

Computer vs. Network Security • Computer security is the generic term for a collection of tools designed to protect data and to thwart hackers. • Network security is the security measures that are needed to protect data during their transmission. • In most systems, the boundaries between computer security and network security are blurred since most, if not all, of today’s systems are distributed in nature.

Goals of Security • Confidentiality :prevents unauthorized useor disclosure of information. • Integrity: assurance that the information has not been tampered. • Availability: information is accessible to authorized entities at the proper time

Basic Terminology • Authentication: Verification that the user’s claimed identity is valid, such as through the use of a password • Authorization: The privileges allocated to an individual (or process) that enable access to a computer resource

Cont. • Non-repudiation: offer of evidence that a party is indeed the sender or a receiver of certain information. (prevents a party in a communication from later denying its participation in communication) • Access control: facilities to determine and enforce who is allowed access to what resources, hosts, software, network connections • Data Origin Authentication: provides assurance that a piece of data originated from a particular source. • Mechanisms: e.g. passwords. • Something you know (password, PIN) • Something you have (ID, smart card) • Something you are (fingerprint, DNA)

Threats and Attacks • A threat : A person, thing, event, or idea which poses some danger to an asset in terms of that asset's confidentiality, integrity or availability. • An attack: A realization of a threat; Any action that attempts to compromise the security of the information owned by an organization/person. • Categories of Attacks • Interruption • Interception • Modification • Fabrication

Interruption • Interruption: an asset of the system becomes lost, unavailable, or unusable. An example is destroy hardware (cutting fiber) or software, erasure of a program or data file, or malfunction of an operating system file manager so that it cannot find a particular disk file. • Denial of service (DoS): • Crashing the server

Interception • An interception means that some unauthorized party has gained access to an asset. An examples are Illicit copying of files and programs and packet sniffers and wiretapping.

Modification • Modification: If an unauthorized party not only accesses but tampers with an asset. • Stop the flow of the message • Delay and modify the message • Release the message again

Fabrication • Unauthorized assumption of other’s identity • Generate and distribute objects under this identity

Security Attack • Interruption: This is an attack on availability • Interception: This is an attack on confidentiality • Modification: This is an attack on integrity • Fabrication: This is n attack on authenticity

Security attacks classification • Passive Attacks • The attacker eavesdrops and read/record messages in transit. • Active Attacks • The attacker may transmit new messages, replay old messages, modify/delete messages on transit.

Virus, Worms, and Trojan Horses • Trojan horse: instructions hidden inside an otherwise useful program that do bad things • Virus: a set of instructions that, when executed, inserts copies of itself into other programs. • Worm: a program that replicates itself by installing copies of itself on other machines across a network. • Trapdoor: an undocumented entry point, which can be exploited as a security flaw • Zombie: malicious instructions installed on a system that can be remotely triggered to carry out some attack with les traceability because the attack comes from another victim.

INTRODUCTION TO COMPUTER & NETWORK SECURITY