Security Concepts
The primary security concerns are intruders that gain access to the system to perform unauthorized actions,insert malicious software (malware), or overwhelm system resources to diminish availability
True
Trust is always restricted to specific functions or ways of behavior and is meaningful only in the context of a security policy
True
With respect to network security, a security protocol may be an enhancement that is part of an existing protocol or a standalone protocol
True
Data Authenticity
A digital object is indeed what it claims to be or what it is claimed to be.
Digital signature algorithm
A digital signature is a value computed with a cryptographic algorithm and associated with a data object in such a way that any recipient of the data can use the signature to verify the data's origin and integrity
Firewall
A hardware and/or software capability that limits access between a network and device attached to the network, in accordance with a specific security policy. The firewall acts as a filter that permits or denies data traffic, both incoming and outgoing, based on a set of rules based on traffic content and/or traffic pattern
Risk
A measure of the extent to which an entity is threatened by a potential circumstance or event, and typically a function of 1) the adverse impacts that would arise if the circumstance or event occurs; and 2) the likelihood of occurrence
Authentication exchange
A mechanism intended to ensure the identity of an entity by means of information exchange.
Network protocol composition:
A network protocol consists of the format and procedures that governs the transmitting and receiving of data between points in a network. A protocol defines the structure of the individual data units and the control commands that manage the data transfer
Threat
A potential for violation of security, which exists when there is a circumstance, capability, action, or event that could breach security and cause harm. That is, a threat is a possible danger that might exploit a vulnerability.
Security Mechanism
A process (or a device incorporating such a process) that is designed to detect, prevent, or recover from a security attack
Masquerade Attack
Takes place when one entity pretends to be a different entity. Usually includes one of the other forms of active attack
IT U-T
The International Telecommunication Union (ITU) is an international organization within the United Nations System in which governments and the private sector coordinate global telecom networks and services. The ITU Telecommunication Standardization Sector (IT U-T) is one of the three sectors of the ITU. IT U-T's mission is the development of technical standards covering all fields of telecommunications. IT U-T standards are referred to as recommendations
Access Control
The ability to limit and control the access to host systems and applications via communications links
Cybersecurity
The collection of tools, policies, security concepts, security safeguards, guidelines, risk management approaches, actions, training, best practices, assurance, and technologies that can be used to protect the cyberspace environment and organization and users' assets.
Generally, an entity is said to trust a second entity when the first entity assumes that the second entity will behave exactly as the first entity expects
True
The other aspect of network security is the protection of network devices, such as routers and switches, and end systems connected to the network, such as client systems and servers
True
message authentication code (MAC)
Another form of single-key cryptographic algorithm. A MAC is a data element associated with a data block or message.
Security Attack
Any action that compromises the security of information owned by an organization
Block Cipher
A block cipher operates on data as a sequence of blocks. In most versions of the block cipher, known as modes of operation, the transformation depends not only on the current data block and the secret key but also on the content of preceding blocks
Trustworthiness
A characteristic of an entity that reflects the degree to which that entity is deserving of trust
Security Service
A processing or communication service that enhances the security of the data processing systems and the information transfers of an organization. It is intended to counter security attacks, and they make use of one or more security mechanisms to provide the service
Stream cipher
A stream cipher operates on data as a sequence of bits. As with the block cipher, the transformation depends on a secret key
Propensity to trust
A tendency to be willing to trust others across a broad spectrum of situations and trust targets. This suggests that every individual has some baseline level of trust that will influence the person's willingness to rely on the words and actions of others
Access control:
A variety of mechanisms that enforce access rights to resources
Attack
An assault on system security that derives from an intelligent threat. That is, an intelligent act that is a deliberate attempt (especially in the sense of a method or technique) to evade security services and violate the security policy of a system.
Mandated trust
An organization establishes a level of trust with another organization based on a specific mandate issued by a third party in a position of authority
Non repudiation
Assurance that the sender of information is provided with proof of delivery and the recipient is provided with proof of the sender's identity, so neither can later deny having processed the information.
System Integrity
Assures that a system performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system.
Data Integrity
Assures that data and programs are changed only in a specified and authorized manner. Encompasses data authenticity and nonrepudiation
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.
Data Confidentiality
Assures that private or confidential information is not made available or disclosed to unauthorized individuals
Availability
Assures that systems work promptly and service is not denied to authorized users.
Two-Key Cryptographic Algorithms:
Asymmetric encryption; Digital signature; Key exchange; User authentication
Active Attack
Attempts to alter system resources or affect their operation. Involves some modification of the data stream or the creation of a false stream. Difficult to prevent because of the wide variety of potential physical, software, and network vulnerabilities. Goal is to detect attacks and to recover from any disruption or delays caused by them.
Passive Attack
Attempts to learn or make use of information from the system but does not affect system resources. They are in the nature of eavesdropping on, or monitoring of, transmissions with the goal of obtaining information that is being transmitted. Two types: Traffic Analysis and the release of message contents
Types of Services
Authentication; Access control; Data confidentiality; data integrity; Nonrepudiation; Availability service
Symmetric encryption takes the following forms
Block Cipher and Stream Cipher
Single-Key Cryptographic Algorithms:
Block cipher symmetric encryption; Stream cipher symmetric encryption; Message Authentication code
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
Key Elements of Network Security:
Communications Security (Network Protocols; Cryptography) and Device Security
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.
Essential Information and Network Security Objectives
Confidentiality, Integrity, Authenticity, Availability, and Accountability
Types of Mechanisms
Cryptographic algorithms; Data integrity; Digital signature; Authentication exchange; Traffic padding; Routing control; Notarization; Access control
Keyless Cryptographic Algorithms:
Cryptographic hash function; Pseudo-random number generator
Digital signature
Data appended to, or a cryptographic transformation of, a data unit that allows a recipient of the data unit to prove the source and integrity of the data unit and protect against forgery.
Communications security
Deals with the protection of communications through the network, including measures to protect against both passive and active attacks. Communications security is primarily implemented using network protocols
Keyless Algorithms
Deterministic functions that have certain properties useful for cryptography
How to achieve Access Control:
Each entity trying to gain access must first be identified, or authenticated, so that access rights can be tailored to the individual
Routing control
Enables selection of particular physically or logically secure routes for certain data and allows routing changes, especially when a breach of security is suspected.
asymmetric encryption algorithms
Encryption algorithms that use a single key
symmetric encryption algorithms
Encryption algorithms that use a single key. With symmetric encryption, an encryption algorithm takes as input some data to be protected and a secret key and produces an unintelligible transformation on that data. A corresponding decryption algorithm takes the transformed data and the same secret key and recovers the original data
Three types of device security:
Firewall; Intrusion Detection; Intrusion Prevention
NIST SP 800-39 (Managing Information Security Risk, March 2011) indicates that such trust relationships with external orgs can be:
Formally established, for example, by documenting the trust-related information in contracts, service-level agreements, statements of work, memoranda of agreement/understanding, or interconnection security agreements; Scalable and inter-organizational or intra-organizational in nature; Represented by simple (bilateral) relationships between two partners or more complex many-to-many relationships among many diverse partners
Intrusion prevention
Hardware or software products designed to detect intrusive activity and attempt to stop the activity, ideally before it reaches its target
Intrusion detection
Hardware or software products that gather and analyze information from various areas within a computer or a network for the purpose of finding, and providing real-time or near-real-time warning of, attempts to access system resources in an unauthorized manner
With respect to internal users, an organization develops a level of trust in individuals by policies in the following two areas:
Human resource security; Security Awareness and Training
Network Protocols
IPsec; TLS; HTTPS; SSH; IEEE 802.11i; S//MIME
Internet Society
ISOC is a professional membership society with worldwide organizational and individual membership. It provides leadership in addressing issues that confront the future of the Internet and is the organization home for the groups responsible for Internet infrastructure standards, including the Internet Engineering Task Force (IETF) and the Internet Architecture Board (IAB). These organizations develop Internet standards and related specifications, all of which are published as Requests for Comments (RFCs)
Replay Attack
Involves the passive capture of a data unit and its subsequent re-transmission to produce an unauthorized effect
Mediated trust
Mediated trust involves the use of a third party that is mutually trusted by two parties, with the third party providing assurance or guarantee of a given level of trust between the first two parties
National Institute of Standards and Technology
NIST is a U.S. federal agency that deals with measurement science, standards, and technology related to U.S. government use and to the promotion of U.S. private-sector innovation. Despite its national scope, NIST Federal Information Processing Standards (FIPS) and Special Publications (SP) have a worldwide impact
Two specific authentication services are defined in X.800:
Peer Entity Authentication and Data Origin Authentication
Information Security
Preservation of confidentiality, integrity, and availability of information. Other properties such as authenticity, accountability, nonrepudiation, and reliability can also be involved.
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
Denial of Service
Prevents or inhibits the normal use or management of communications facilities
Network Security
Protection of networks and their service from unauthorized modification, destruction, or disclosure, and provision of assurance that the network performs its critical functions correctly and there are no harmful side effects
Availability Service
Protects a system to ensure its availability. This service addresses the security concerns raised by denial-of-service attacks. It depends on proper management and control of system resources and thus depends on access control service and other security services
Peer Entity Authentication
Provides for corroboration of the identity of a peer entity in an association. Two entities are considered peers if they implement the same protocol in different systems. Peer entity authentication is provided for use at the establishment of, or at times during the data transfer phase of, a connection. It attempts to provide confidence that an entity is not performing either a masquerade or an unauthorized replay of a previous connection
Data Origin Authentication
Provides for the corroboration of the source of a data unit. It does not provide protection against the duplication or modification of data units. This type of service supports applications like electronic mail, where there are no ongoing interactions between the communicating entities.
Types of Passive Attacks
Release of message contents; Traffic analysis
Types of Active Attacks
Replay; Data modification; Masquerade; Denial of Service
Two factors affecting the trustworthiness of information systems are
Security Functionality and Security Assurance
Computer Security Challenges
Security is not simple; Potential attacks on the security features need to be considered; Procedures used to provide particular services are often counter-intuitive; It is necessary to decide where to use the various security mechanisms; Requires constant monitoring; Is too often an afterthought; Little benefit from security investment is perceived until a security failure occurs; Strong security is often viewed as an impediment to efficient and user-friendly operation
Data Modification
Some portion of a legitimate message is altered, or messages are delayed or reordered to produce an unauthorized effect
Security assurance
The grounds for confidence that the security functionality is effective in its application. This area is addressed by security management techniques, such as auditing and incorporating security considerations into the system development life cycle
Traffic padding
The insertion of bits into gaps in a data stream to frustrate traffic analysis attempts
User authentication
The process of authenticating that a user attempting to access an application or service is genuine and, similarly, that the application or service is genuine
Key exchange
The process of securely distributing a symmetric key to two or more parties
Data Confidentiality
The protection of transmitted data from passive attacks and protection of traffic flow from analysis
Security functionality
The security features/functions employed within the system. These include cryptographic and network security technologies
Notarization
The use of a trusted third party to assure certain properties of a data exchange
Data integrity
This category covers a variety of mechanisms used to assure the integrity of a data unit or stream of data units.
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
Direct historical trust
This type of trust is based on the security-related track record exhibited by an organization in the past, particularly in interactions with the organization seeking to establish trust
Validated trust
Trust is based on evidence obtained by the trusting organization about the trusted organization or entity. The information may include information security policy, security measures, and level of oversight
Three related concepts relevant to a trust model
Trustworthiness; Propensity to Trust; Risk
Cryptographic algorithms
We can distinguish between reversible cryptographic mechanisms and irreversible cryptographic mechanisms. A reversible cryptographic mechanism is simply an encryption algorithm that allows data to be encrypted and subsequently decrypted. Irreversible cryptographic mechanisms include hash algorithms and message authentication codes, which are used in digital signature and message authentication applications.
The MAC is generated by:
a cryptographic transformation involving a secret key and, typically, a cryptographic hash function of the message
Trust
confidence that an entity will perform in a way that will not prejudice the security of the user of the system of which that entity is apart
Connection-oriented integrity service
deals with a stream of messages, assures that messages are received as sent with no duplication, insertion, modification,reordering, or replays
connectionless integrity service
deals with individual messages without regard to any larger context,generally provides protection against message modification only
Single-key Algorithms:
depend on the use of a secret key
Cryptographic hash function:
has additional properties that make it useful as part of another cryptographic algorithm, such as a message authentication code or a digital signature
The recipient of the message plus the MAC can:
perform the same calculation on the message; if the calculated MAC matches the MAC accompanying the message, this provides assurance that the message has not been altered
pseudorandom number generator
produces a deterministic sequence of numbers or bits that has the appearance of being a truly random sequence
The MAC is designed so:
that someone in possession of the secret key can verify the integrity of the message
SP 800-39 defines trustworthiness for information systems as
the degree to which information systems (including the information technology products from which the systems are built) can be expected to preserve the confidentiality, integrity, and availability of the information being processed, stored, or transmitted by the systems across the full range of threats
One of the most widely accepted and most cited definitions of trust is:
the willingness of a party to be vulnerable to the actions of another party based on the expectation that the other will perform a particular action important to the trust or,irrespective of the ability to monitor or control that other party
Hash function
turns a variable amount of text into a small, fixed-length value called a hash value, hash code, or digest
