Introduction to Information Security Spring 2014

Outline Introduction Attacks, services and mechanisms Security threats and attacks Security services Methods of Defense A model for Internetwork Security

Introduction Goal Information Security Computer Security Network Services Computer Security Network Security Automated tools for protecting info on the computer Measures to protect data during their transmission on the network

Security Trends High Low Smart Phone Attack DDoS to DNS 2003 BotNet Attack 2009 Low

What’s is “Computer Security”? “A computer is secure if you can depend on it and its software to behave as you expect.” – Garfinkel and Spafford, 1991. “Computer security is preventing attackers from achieving objectives through unauthorized access or use of computers and networks.” – John D. Howard, 1995. “Computer security is measures and controls that ensure confidentiality, integrity, availability of information systems.” – American National Standards Institute, Inc. Telecom Glossary 2000.

Hacking Attack using the vulnerability of protocol Malicious code DoS Sniffing Session Hijacking Spoofing Malicious code Virus Trojan horse Back door Worm John Draper, Phone hacker

Virus and Worm What is Virus? Self-replicating code Inserts itself into other executable code Contains a malicious function, called payload (can be empty) Native code which infects executable files Distribution by Email and File sharing Often requires a trigger from a user e.g. execute infected application Virus is often used as a collective term for malware

Virus and Worm What is Worm? First Internet worm in 1988 Different to a virus Stand-alone program Does not infect an application Spreads itself through the network automatically Usually spread much faster than viruses Worms often use exploits to propagate SQL Slammer – MS SQL Server Slapper - Apache/Mod-SSL Code Red – MS Internet Information Server

Trojan Horse A destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. A Trojan horse can be deliberately attached to otherwise useful software by a cracker, or it can be spread by tricking users into believing that it is a useful program. The term comes from the a Greek story of the Trojan War : between Greek and Troy

Attacks, Services and Mechanisms Security Attack: Any action that compromises the security of information. Security Mechanism: A mechanism that is designed to detect, prevent, or recover from a security attack. Security Service: A service that enhances the security of data processing systems and information transfers. A security service makes use of one or more security mechanisms.

Security Threats & Attacks A possible danger that might exploit a vulnerability in given circumstance, capability, and action or event to breach security and cause harm Attacks An assault on system security that derives from an intelligent threat

Security Threats

Security Threats Interruption: This is a threat on availability Interception: This is a threat on confidentiality Modification: This is a threat on integrity Fabrication: This is a threat on authenticity

Security Attacks • Passive Attack : Attempts to learn or make use of information from the system, but no affect on system resources - Release of message contents - Traffic analysis • Active Attack : Attempts to data system resources or affect their operations - Masquerade - Replay - Modification of message - Denial of service : 2003.1.25 Internet Chaos, 2007.7.7/ 2011.3.3 DDoS Attack

Release of Message Contents Sensitive or confidential information needs to be prevented from an opponent who will learn the contents of the there transmissions Darth Read contents of message from Bob to Alice Internet or other comms facility Bob Alice

Internet or other communications facility Traffic Analysis If the contents of messages are masked or protected by encryption, and opponent might still be able to observe the pattern of messages. • such as source and destination of communicating hosts, • frequency and length of messages being exchanged. Darth Observe pattern of messages from Bob to Alice Internet or other communications facility Bob Alice

Internet or other comms facility Masquerade • Taking place when one entity pretends to be a different entity • Enabling an authorized entity with few privileges to obtain extra privileges by impersonating an entity that has those privileges. Darth Read contents of message from Bob to Alice Internet or other comms facility Bob Alice

Internet or other comms facility Replay attack The passive capture of a data unit and its subsequent retransmission to produce an unauthorized effect. Darth Capture message from Bob to Alice; later replay message to Alice Internet or other comms facility Bob Alice

Modification of Message Some portion of legitimate message altered, delayed, or reordered to produce an unauthorized effect. Darth Darth modifies message from Bob to Alice Internet or other comms facility Bob Alice

Denial of Service The normal use of communications facilities prevented or inhibited, such as • Suppressing all messages directed to a particular destination. • The disruption of an entire network by disabling the network • The degradation of performance by overloading it with messages

An Architecture of DDoS Attack Daemon Master Daemon Daemon Daemon Daemon Real Attacker Victim

Security Service A service that is provided by a protocol layer of communicating open system and that ensures adequate security of the systems or of data transfer Security services implement security policies and are implemented by security mechanisms Classification of the services Authentication - Data Integrity Access control - Nonrepudiation Data confidentiality - Availability

Authentication This service is concerned with assuring that a communication is authentic Data origin authentication (in the case of a single message) The function of the authentication service is to assure the recipient that the message is from the original source. No service on duplication or modification. Peer entity authentication (in a connection-oriented transmission i.e TCP) At the time of connection initiation, the service assures that the two entities are authentic On the way of transmissions, the service assures that the connection is not interfered by a third party to masquerade as one of the entities.

Access Control The prevention of unauthorised use of a resource In the context of network security, this service is the ability to limit and control the access to host systems and applications via communications links. Each entity must be identified or authenticated then, access rights can be tailored to the individual.

Data Confidentiality The protection of transmitted data from passive attacks. Types of data confidentiality Connection confidentiality (all user data on a connection) Connectionless confidentiality (all user data in a single msg.) Selective field confidentiality (specific fields within a use data) Traffic-flow confidentiality (information for traffic flow)

Data Integrity To provide the assurance that the received data are exactly the same as the data transmitted by an authorised entity. ※ no modification, insertion, deletion, or replay A connection-oriented / connectionless integrity service Connection-oriented : deals with a stream of messages & assures no duplication, alteration, or replays on the messages. Connectionless : deals with individual messages & may provide protection on data modification Integrity service with / without recovery The automated recovery mechanism is more attractive.

Nonrepudiation To prevent either sender or receiver from denying a transmitted message. Origin (sender): Proof that the message was sent by the specified party. Destination (receiver): Proof that the message was received by the specified party.

Availability Provides the normal use of a system or system resource Addresses the security concerns raised by denial-of-service attack.

Security Mechanisms Specific Security Mechanisms Implemented in a specific protocol layer. Pervasive Security Mechanisms Not specific to any particular protocol layer or security service.

A Model for Network Security Trusted third party (e.g., arbiter, distributer of secret information) Information channel Security-related transformation Security-related transformation Message Secure Message Secure Message Message Secret information Secret information Opponent

Methods of Defence Encryption Software Controls (access limitations in a data base, in operating system protect each user from other users)‏ Hardware Controls (smartcard)‏ Policies (frequent changes of passwords)‏ Physical Controls

Summary We deals with security trends Security attacks such as passive attacks and active attacks Security services such as authentication, access control, data confidentiality, data integrity, nonrepudiation and availability service A model for network security including Opponent, Access Channel, Gatekeeper Function and Information System

Outline of the Course This chapter serves as an introduction to the entire course. The remainder of the book is organized into three parts: Part One : Provides a concise survey of the cryptographic algorithms and protocols underlying network security applications, including encryption, hash functions, digital signatures, and key exchange. Part Two : Examines the use of cryptographic algorithms and security protocols to provide security over networks and the Internet. Topics covered include user authentication, e-mail, IP security, and Web security. Part Three : Deals with security facilities designed to protect a computer system from security threats, including intruders, viruses, and worms. This part also looks at firewall technology.