Chapter 1: Network Security Concepts PDF

Cryptographic algorithms and protocols can be grouped into four main areas: Symmetric encryption Used to conceal the contents of blocks or streams of data of any size, including messages, files, encryption keys, and passwords Asymmetric encryption Used to conceal small blocks of data...

Cryptographic algorithms and protocols can be grouped into four main areas: Symmetric encryption Used to conceal the contents of blocks or streams of data of any size, including messages, files, encryption keys, and passwords Asymmetric encryption Used to conceal small blocks of data, such as encryption keys and hash function values, which are used in digital signatures Data integrity algorithms Used to protect blocks of data, such as messages, from alteration Authentication protocols Schemes based on the use of cryptographic algorithms designed to authenticate the identity of entities  The field of network and Internet security consists of: measures to deter, prevent, detect, and correct security violations that involve the transmission of information  Computer Security The NIST Computer Security Handbook defines the term computer security as: “the protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability and confidentiality of information system resources” (includes hardware, software, firmware, information/ data, and telecommunications) Computer Security Objectives Confidentiality Data confidentiality Assures that private or confidential information is not made available or disclosed to unauthorized individuals Privacy Assures that individuals control or influence what information related to them may be collected and stored and by whom and to whom that information may be disclosed Integrity Data integrity Assures that information and programs are changed only in a specified and authorized manner System integrity Assures that a system performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system Availability Assures that systems work promptly and service is not denied to authorized users CIA Triad Possible additional concepts: Authenticity Accountability Verifying that users The security goal that are who they say they generates the are and that each requirement for input arriving at the actions of an entity to system came from a be traced uniquely to trusted source that entity Breach of Security Levels of Impact The loss could be expected to have a severe or High catastrophic adverse effect on organizational operations, organizational assets, or individuals The loss could be expected to have a Moderate serious adverse effect on organizational operations, organizational assets, or individuals The loss could be expected to have a limited adverse Low effect on organizational operations, organizational assets, or individuals Computer Security Challenges Security is not simple Security mechanisms typically involve more than a Potential attacks on the particular algorithm or security features need to be protocol considered Security is essentially a battle Procedures used to provide of wits between a particular services are often perpetrator and the designer counter-intuitive Little benefit from security It is necessary to decide investment is perceived until where to use the various a security failure occurs security mechanisms Strong security is often Requires constant monitoring viewed as an impediment to efficient and user-friendly Is too often an afterthought operation  OSI Security Architecture Security attack Any action that compromises the security of information owned by an organization Security mechanism A process (or a device incorporating such a process) that is designed to detect, prevent, or recover from a security attack Security service A processing or communication service that enhances the security of the data processing systems and the information transfers of an organization Intended to counter security attacks, and they make use of one or more security mechanisms to provide the service  Table 1.1 Threats and Attacks (RFC 4949)  Security Attacks A means of classifying security attacks, used both in X.800 and RFC 4949, is in terms of passive attacks and active attacks A passive attack attempts to learn or make use of information from the system but does not affect system resources An active attack attempts to alter system resources or affect their operation  Passive Attacks Are in the nature of eavesdropping on, or monitoring of, transmissions Goal of the opponent is to Two types of passive obtain information that is being transmitted attacks are: The release of message contents Traffic analysis  Active Attacks Involve some modification of the data stream or the creation of a Takes place when one entity pretends to be a different entity false stream Masquerade Usually includes one of the other forms of active attack Difficult to prevent because of the wide variety of potential Involves the passive capture of a physical, software, and network data unit and its subsequent Replay retransmission to produce an vulnerabilities unauthorized effect Goal is to detect attacks and to recover from any disruption or Some portion of a legitimate delays caused by them Modification message is altered, or messages are of messages delayed or reordered to produce an unauthorized effect Denial of Prevents or inhibits the normal use or management of communications service facilities  Security Services Defined by X.800 as: A service provided by a protocol layer of communicating open systems and that ensures adequate security of the systems or of data transfers Defined by RFC 4949 as: A processing or communication service provided by a system to give a specific kind of protection to system resources X.800 Service Categories Authentication Access control Data confidentiality Data integrity Nonrepudiation  Authentication Concerned with assuring that a communication is authentic In the case of a single message, assures the recipient that the message is from the source that it claims to be from In the case of ongoing interaction, assures the two entities are authentic and that the connection is not interfered with in such a way that a third party can masquerade as one of the two legitimate parties Two specific authentication services are defined in X.800: Peer entity authentication Data origin authentication  Access Control The ability to limit and control the access to host systems and applications via communications links To achieve this, each entity trying to gain access must first be indentified, or authenticated, so that access rights can be tailored to the individual  Data Confidentiality The protection of transmitted data from passive attacks Broadest service protects all user data transmitted between two users over a period of time Narrower forms of service includes the protection of a single message or even specific fields within a message The protection of traffic flow from analysis This requires that an attacker not be able to observe the source and destination, frequency, length, or other characteristics of the traffic on a communications facility Data Integrity Can apply to a stream of messages, a single message, or selected fields within a message Connection-oriented integrity service, one that deals with a stream of messages, assures that messages are received as sent with no duplication, insertion, modification, reordering, or replays A connectionless integrity service, one that deals with individual messages without regard to any larger context, generally provides protection against message modification only  Nonrepudiation Prevents either sender or receiver from denying a transmitted message When a message is sent, the receiver can prove that the alleged sender in fact sent the message When a message is received, the sender can prove that the alleged receiver in fact received the message  Table 1.2 Security Services (X.800) (This table is found on page 38 in textbook) Security Mechanisms (X.800) Specific Security Mechanisms Encipherment Digital signatures Access controls Data integrity Pervasive Security Mechanisms Authentication exchange Traffic padding Trusted functionality Routing control Security labels Notarization Event detection Security audit trails Security recovery  Table 1.3 Security Mechanisms (X.800) (This table is found on pages 40-41 in textbook) Model for Network Security Network Access Security Model  Unwanted Access Placement in a computer system of logic that exploits vulnerabilities in the system and that can affect application programs as well as utility programs such as editors and compilers Programs can present two kinds of threats: Information access threats Intercept or modify data on behalf of users who should not have access to that data Service threats Exploit service flaws in computers to inhibit use by legitimate users