Computer Security: Principles and Practice Chapter 3 PDF

Computer Security: Principles and Practice Fifth Edition Chapter 3 User Authentication Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright © 2024, 2018, 2015 Pearson Education,...

Computer Security: Principles and Practice Fifth Edition Chapter 3 User Authentication Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Multifactor Authentication: During the multifactor authentication process, the client exchanges an authentication protocol with authentication logic using the first factor. If the message fails, the authentication protocol drops. If the message passes, the client’s authentication protocol must then pass the authentication logic using the second factor, and a similar process goes on. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  The Vulnerability of Passwords Offline dictionary attack: The attacker obtains the system password file and compares the password hashes against hashes of commonly used passwords. Specific account attack: The attacker targets a specific account and submits password guesses until the correct password is discovered Popular password attack: A variation of the preceding attack is to use a popular password and try it against a wide range of user IDs Workstation hijacking: The attacker waits until a logged-in workstation is unattended Exploiting user mistakes: If the system assigns a password, the user is likelier to write it down because it is difficult to remember. Exploiting multiple password use: Attacks can become much more effective or damaging if different network devices share a similar password for a given user. Electronic monitoring: If a password is communicated across a network to log on to a remote system, it is vulnerable to eavesdropping Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved The salt serves three purposes: 1. It prevents duplicate passwords from being visible in the password file. 2. It greatly increases the difficulty of offline dictionary attacks 3. It becomes nearly impossible to find out whether a person with passwords on two or more systems have used the same password on all of them. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Password Authentication Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Password Selection Strategies Our goal, then, is to eliminate guessable passwords while allowing the user to select a memorable password. Four basic techniques are in use: – User education – Computer-generated passwords – Reactive password checking – Complex password policy ▪ Password must have at least sixteen characters (basic 16). ▪ Password must have at least eight characters, including an uppercase and lowercase letter, a symbol, and a digit. It may not contain a dictionary word. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Types of Cards Used as Tokens Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 3.5 Smart Card/Reader Exchange Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 3.3 Electronic Functions and Data for eID Cards CA N = card access number M R Z = machine-readable zone P AC E = password authenticated connection establishment P I N = personal identification number Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 3.6 User Authentication with eID Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Cost versus Accuracy of Various Biometric Characteristics in User Authentication Schemes Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 3.8 A Generic Biometric System Enrollment creates an association between a user and the user’s biometric characteristics. Depending on the application, user authentication involves either verifying that a claimed user is the actual user or identifying an unknown user. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved 1. Also referred to as single-key encryption, the universal technique for providing confidentiality for transmitted or stored data is __________. 2. There are two general approaches to attacking a symmetric encryption scheme: cryptanalytic attacks and __________ attacks. 3. The __________ algorithm takes the ciphertext and the secret key and produces the original plaintext. 4. A __________ attack exploits the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used. 5. A __________ processes the plaintext input in fixed-size blocks and produces a block of ciphertext of equal size for each plaintext block. 6. A __________ processes the input elements continuously, producing output one element at a time. 7. The two criteria used to validate that a sequence of numbers is random are independence and _________. 8. A _________ is a hardware device that sits between servers and storage systems and encrypts all data going from the server to the storage system and decrypts data going in the opposite direction. 9. Key sizes of __________ or greater are effectively unbreakable using simply a brute-force approach. 10. The __________ is a pair of keys selected so that if one is used for encryption, the other is used for decryption. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Answer 1. symmetric encryption 2. brute-force 3. decryption 4. cryptanalytic 5. block cipher 6. stream cipher 7. uniform distribution 8. back-end appliance 9. 128 bits 10. public and private key Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Computer Security: Principles and Practice Fifth Edition Chapter 4 Access Control Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Access Control Security Requirements (SP 800-171) Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Access Control Context Authentication: Verification that the credentials of a user or other system entity are valid. Authorization: The granting of a right or permission to a system entity to access a system resource. This function determines who is trusted for a given purpose Audit: An independent review and examination of system records and activities in order to test for adequacy of system controls Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Relationship among Access Control and Other Security Functions Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved The basic elements of access control are subject, object, and access right. Owner: This may be the creator of a resource, such as a file. Group: In addition to the privileges assigned to an owner, a named group of users may also be A subject is an entity capable of accessing objects. granted access rights, World: The least amount of access is granted to users who are able to access the system but are not included in the categories owner and group for this resource Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  An access right describes the way in which a subject may access an object. Access rights could include the following: Read: User may view information in a system resource (e.g., a file, selected records in a file, selected fields within a record, or some combination). Read access includes the ability to copy or print. Write: The user may add, modify, or delete data in system resources (e.g., files, records, programs). Write access includes read access. Execute: The user may execute specified programs. Delete: The user may delete certain system resources, such as files or records. Create: The user may create new files, records, or fields. Search: The user may list the files in a directory or otherwise search the directory. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  DISCRETIONARY ACCESS CONTROL A discretionary access control scheme is one in which an entity may be granted access rights that permit the entity, by its own volition, to enable another entity to access some resource. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Authorization Table for Files Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Extended Access Control Matrix Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved ROLE-BASED ACCESS CONTROL: Users, Roles, and Resources ➔RBAC is based on the roles that users assume in a system rather than the user’s identity. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Access Control Matrix Representation of RBAC Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.8 A Family of Role-Based Access Control Models Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 4.4 Scope RBAC Models Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.9 Example of Role Hierarchy Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.10 ABAC Scenario Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.11 ACL and ABAC Trust Relationships Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Unnumbered Table 1 Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.12 Identity, Credential, and Access Management (ICAM) Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.13 Identity Information Exchange Approaches Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 4.5a Functions and Roles for Banking Example Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 4.5b Functions and Roles for Banking Example Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 4.5c Functions and Roles for Banking Example Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.14 Example of Access Control Administration Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 4.15 VAX/VMS Access Modes Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Computer Security: Principles and Practice Fifth Edition Chapter 1 Overview Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 1.1 Essential Network and Computer Security Requirements Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.1 Computer Security Terminology Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 1.2 Security Concepts and Relationships Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.2 Threat Consequences and the Types of Threat Actions that Cause Each Consequence Source: Based on RFC 4949 Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 1.3 Scope of Computer Security Note: This figure depicts security concerns other than physical security, including control of access to computers systems, safeguarding of data transmitted over communications systems, and safeguarding of stored data. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.3 Computer and Network Assets, with Examples of Threats Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.4 (1 of 3) Security Requirements Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.4 (2 of 3) Security Requirements (continued) Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Table 1.4 (3 of 3) Security Requirements (continued) Source: Based on FIPS 200 Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 1.4 Defense in Depth and Attack Surface Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Figure 1.5 An Attack Tree for Internet Banking Authentication Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Chapter 2 Cryptographic Tools  Simplified Model of Symmetric Encryption The plain text input X enters the encryption algorithm (such as D E S). The resulting transmitted cypher text Y equals E [ K, X ] enters the decryption algorithm, which is the reverse of the encryption algorithm. This algorithm produces X equals D [ K, Y ] as the plain text output. Note: The sender and recipient can access encryption and decryption algorithms via a secret key, K. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Comparison of Three Popular Symmetric Encryption Algorithms DE S = Data Encryption Standard A ES = Advanced Encryption Standard Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Average Time Required for Exhaustive Key Search Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Types of Symmetric Encryption Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Message Authentication Using a Message Authentication Code (MAC) The diagram consists of three vertical rectangular strips connected unidirectionally with each other. The strip at the left end consists of the message that has to be transmitted to the consecutive strips. Also, there is an M A C algorithm that takes K and the message and adds an M A C segment to the message. The M A C segment also passes through the consecutive segments located at the bottom of the remaining two rectangular strips. At the receiving end of the message, another M A C algorithm is shown that takes K and produces an M A C segment which is compared with the M A C segment received from the message. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Cryptographic Hash Function; h = H(M) The illustration shows a hand juicer whose upper end takes the input H and the output hash value h is given out from the left opening which is of a fixed length. The hash function H converts a message or data block M of variable length L bits into a bash value h of a fixed length. Note: P, L equals padding plus length field. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Message Authentication Using a One-Way Hash Function Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Unnumbered Table 1 The strength of a hash function against brute-force attacks depends solely on the length of the hash code produced by the algorithm. For a hash code of length n, the level of effort required is proportional to the following: Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Public-Key Cryptography Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Applications for Public-Key Cryptosystems Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Simplified Depiction of Essential Elements of Digital Signature Process Public-key encryption can be used for authentication with a technique known as the digital signature. Bob wants to send a message to Alice. (It is not important that the message be kept secret; he wants Alice to be certain that the message is indeed from him.) For this purpose, Bob uses a secure hash function, such as SHA-512, to generate a hash value for the message. That hash value and Bob’s private key serve as input to a digital signature generation algorithm that produces a short block that functions as a digital signature. Bob sends the message with the signature attached. When Alice receives the message plus signature, she Calculates a hash value for the message; Provides the hash value and Bob’s public key as inputs to a digital signature verification algorithm. If the algorithm returns the result that the signature is valid, Alice is assured that Bob signed the message. The digital signature does not provide confidentiality. That is, the message being sent is safe from alteration but not safe from eavesdropping. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Simplified Depiction of Essential Elements of Digital Signature Process Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Public-Key Certificate Use On the face of it, the point of public-key encryption is that the public key is public. Thus, if there is some broadly accepted public-key algorithm, any participant can send his or her public key to any other participant or broadcast the key to the community. Although this approach is convenient, it has a major weakness. The solution to this problem is the public-key certificate. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Public-Key Certificate Use The key steps can be summarized as follows: 1. User software (client) creates public and private keys. 2. The client prepares an unsigned certificate that includes the user ID and the user’s Public key. 3. The user provides the unsigned certificate to a CA in a secure manner. This might require a face-to-face meeting, 4. CA creates a signature as follows: a. CA uses a hash function to calculate the hash code of the unsigned certificate. A hash function maps a variable-length data block or message into a fixed-length value called a hash code b. CA generates a digital signature using the CA’s private key and a signature Generation algorithm. 5. CA attaches the signature to the unsigned certificate to create a signed certificate Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Public-Key Certificate Use 6. CA returns the signed certificate to the client. 7. The client may provide the signed certificate to any other user. 8. Any user may verify that the certificate is valid as follows: a. User calculates the hash code of the certificate (not including signature). b. User verifies the digital signature using CA’s public key and the signature verification algorithm. The algorithm returns a result of either signature valid or invalid. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Public-Key Certificate Use Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  Digital Envelopes Another application in which public-key encryption is used to protect a symmetric key is the digital envelope, which can be used to protect a message without needing first to arrange for the sender and receiver to have the same secret key. The technique is referred to as a digital envelope, which is the equivalent of a sealed envelope containing an unsigned letter. 1. Prepare a message. 2. Generate a random symmetric key that will be used this one time only. 3. Encrypt that message using symmetric encryption the one-time key. 4. Encrypt the one-time key using public-key encryption with Alice’s public key. 5. Attach the encrypted one-time key to the encrypted message and send it to Alice. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Digital Envelopes Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved  T F 1. Threats are attacks carried out. T F 2. Computer security protects information system resources’ integrity, availability, and confidentiality. T F 3. Data integrity assures that information and programs are changed only in a specified and authorized manner. T F 4. Availability assures that systems work promptly and service is not denied to authorized users. T F 5. The “A” in the CIA triad stands for “authenticity”. T F 6. In the context of security our concern is with the vulnerabilities of system resources. T F 7. Hardware is the most vulnerable to attack and the least susceptible to automated controls. T F 8. Contingency planning is a functional area that primarily requires computer security technical measures. T F 9. An attack surface consists of the reachable and exploitable vulnerabilities in a system. T F 10. The first step in devising security services and mechanisms is to develop a security policy. T F 11. Assurance is the process of examining a computer product or system with respect to certain criteria. Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved 1. F 2. T 3. T 4. T 5. F 6. T 7. T 8. F 9. T 10. T 11. F Copyright © 2024, 2018, 2015 Pearson Education, Inc. All Rights Reserved