Computer Security Chapter 1

Chapter 1: Basic Security Concepts

• Computer security protects computer system assets (items with value).
• Assets include hardware, software, data, processes, storage media, and people.
• The principle of easiest penetration states that intruders will likely use readily available means.

Introduction

• Computer systems (hardware, software, and data) require security protection due to their value.
• Three classifications of protection are:
  • Prevention: measures to prevent damage.
  • Detection: measures to identify when and how assets are damaged.
  • Reaction: measures to recover from damage.

Example from Physical world

• Prevention: locks, walls, etc.
• Detection: burglar alarms, CCTV cameras.
• Reaction: contacting the police, replacing lost items.

Example from Cyber World: Credit Card Fraud

• Prevention: encryption, merchant verification before accepting credit cards; avoiding use of credit cards online.
• Detection: unauthorized transactions appearing on statements.
• Reaction: requesting new card numbers, recovering losses from fraudsters or issuers.

Security Goals - CIA Triad

• Confidentiality: assets are accessible only to authorized parties.
• Integrity: assets can only be modified by authorized parties in authorized ways.
• Availability: assets are accessible to authorized parties when needed.
• Security is achieved through a combination of these aspects, from the asset's perspective, not the user's.

Confidentiality

• Computer-related assets are accessed only by authorized parties.
• Access includes not only reading but also viewing, printing, and knowing the asset exists.
• A subject, object, access mode, and policy describe access to data items.

Integrity

• Assets can be modified only by authorized parties in authorized ways.
• Modification includes writing, changing status, deleting, and creating.
• Integrity means different things in different contexts.
• Examples of integrity include accuracy, precision, being unmodified, and being modified only by authorized entities and processes. Integrity should be internally consistent.

Integrity (continued)

• Integrity can mean two or more properties.
• Welke & Mayfield recognize three aspects:
  • Authorized actions
  • Separation and protection of resources.
  • Error detection and correction.

Availability

• Assets are accessible to authorized parties at appropriate times.
• Access should not be prevented from legitimate users.
• Availability is sometimes known as the opposite: denial of service (DoS).
• Availability applies to data and services.
• Definition of availability depends on capacity to meet service's needs.

Other Protection Requirements

• The AAA system manages user access while enforcing policies and privileges and measuring network resource use.
  • Authentication: verifying user identity
  • Authorization: determining user access permissions.
  • Accounting: tracking user activities and events.

Vulnerabilities and Threats

• A vulnerability is a weakness in a system's design or implementation that might be exploited to cause loss or harm.
  • Examples: unauthorized data manipulation due to a lack of user verification; hardware failures; inappropriate software protections
• A threat is a set of circumstances with the potential to cause loss or harm.
  • Understanding the difference between vulnerability (weakness) and threat (potential harm).
  • Example: rising water levels causing harm.

Computer Network Vulnerabilities

• Various network components are potential vulnerabilities, like hardware failures, unauthorized access, inadequate software protection, improper connections, cross-coupling, and misconfigured protective features.

Security Threats

• The CIA triad viewed from a different perspective, focusing on the nature and type of harm caused to assets, categorized into four acts:
  • Interruption: assets are unusable or destroyed (e.g., hard disk destruction, communication line cut).
  • Interception: unauthorized access to assets (e.g., wiretapping, illicit copying).
  • Modification: unauthorized tampering with assets (e.g., changing data file values, altering programs).
  • Fabrication: inserting counterfeit assets, damaging integrity (e.g., adding records to a file, inserting spurious messages).

Examples of Security

• Interruption (hard disk destruction, communication line cutting, disabling file management system).
• Interception (wiretapping, illicit copying of files or programs).
• Modification (changing data values, altering programs, modifying files).
• Fabrication (adding records to a file, inserting spurious network messages).

Explore the foundational concepts of computer security in this quiz. Learn about asset protection, the principle of easiest penetration, and the three classifications of security measures: prevention, detection, and reaction. Test your understanding of these vital topics to safeguard computer systems.