Comprehensive Study Notes: The Internet, Web Technologies, and Cyber Security

The Internet versus the World Wide Web

• The Internet:     * Defined as the infrastructure comprised of a global network of connected computers.     * Provides the fundamental communication system for various services.     * Supports services beyond the web, including email and File Transfer Protocol (FTP).     * Can be utilized without a web browser (e.g., through email clients or FTP software).

• The World Wide Web (Web):     * Defined as the collection of websites and web pages accessed via the Internet.     * A service that operates on top of the Internet infrastructure.     * Used specifically to view web pages and websites.     * Requires a web browser for access.

Uniform Resource Locators (URL)

• Definition: A URL (Uniform Resource Locator) is a text-based address specifically for a web page or a file located on the World Wide Web.

• Components of a URL:     * Protocol: (e.g., https://) Indicates the method of data transfer.     * Domain Name: (e.g., computerhope.com) Identifies the specific website.     * Web page or file name: (e.g., /jargon.html) Identifies the exact page or file on the server.

• Detailed Example: Within the URL https://www.computerhope.com/jargon.html:     * https represents the protocol.     * computerhope.com represents the domain name.     * jargon.html represents the web page or file name.

Hypertext Transfer Protocol (HTTP) and HTTPS

• Hypertext Transfer Protocol (HTTP):     * Purpose: A protocol used to transfer web pages from a web server to a web browser.     * Security Factor: Data is transferred without encryption.     * Operation:         1. User enters a URL.         2. Browser sends an HTTP request to the server.         3. Server sends an HTTP response containing the requested page.         4. Browser receives and displays the data.

• Hypertext Transfer Protocol Secure (HTTPS):     * Purpose: Used to securely transfer web pages and data between a browser and a server using encryption to protect data.     * Operation:         1. User enters a URL.         2. Browser sends an HTTPS request to the server.         3. Server provides a digital certificate and its public key.         4. Browser uses the public key to encrypt data.         5. Server uses its private key to decrypt data.         6. Server sends requested data in encrypted form.         7. Browser decrypts and displays the page.     * Benefits: Protects sensitive data like passwords and payment details.

Security Mechanisms of HTTPS

• Foundational Protocols: Uses SSL (Secure Socket Layer) / TLS (Transport Layer Security) for communication.

• Digital Certificates: Provided by the server to confirm its identity and share its public key.

• Asymmetric Encryption: Uses two distinct keys (public and private).     * The browser encrypts data using the server's public key.     * Only the server's private key (kept secret) can decrypt that data.

• Data Integrity: Prevents unauthorized parties from reading or modifying the transmitted information.

Web Browser Purpose and Functions

• Main Purpose: To render HTML and display web pages.

• Rendering Definition: The process of transforming website code into a visual web page for the user.

• Browser Functions:     * Bookmarks/Favourites: Saves website links for rapid access later.     * Browsing History: Maintains a chronological list of visited websites.     * Multiple Tabs: Allows the viewing of several pages simultaneously within the same window.     * Cookies Storage: Saves small files to remember user login details or settings.     * Navigation Tools: Inclusion of buttons for Back, Forward, Refresh, and Home.     * Address Bar: A field for typing URLs directly.

Process of Locating and Retrieving Web Pages

• Step-by-Step Procedure:     1. User enters a URL into the browser.     2. Browser sends a request to locate the page.     3. The Domain Name Server (DNS) translates the domain name into a numeric IP address.     4. The browser uses the IP address to contact the Web Server.     5. The Web Server retrieves the requested page (written in HTML).     6. The browser renders the HTML and displays the page on the device.

Domain Name System (DNS) Details

• Definition: A naming database that translates human-readable domain names into IP addresses used by computers.

• Example: Translates a name like example.com into an IP address such as $203.0.113.72$.

• Utility: Eliminates the need for users to remember complex numeric strings to visit websites.

Cookies: Types and Usage

• Definition: Small text files sent from a web server and stored by a browser on a user's device.

• Primary Uses:     * Saving personal details.     * Tracking preferences (language, theme).     * Maintaining items in an online shopping cart.     * Storing login credentials.

• Types of Cookies:     * Session Cookies: Temporary; stored in memory (RAM); deleted when the browser is closed.     * Persistent Cookies: Stored on secondary storage (hard drive); remain for a set period until they expire or are manually deleted.

• Storage of Payment Details via Cookies:     1. Web server sends cookie when payment details are entered.     2. Cookie stores an identifier or encrypted info on secondary storage.     3. On revisit, the server requests the cookie.     4. Browser sends it back, and the server automatically fills in payment fields.

• User Concerns/Privacy:     * Users may be unaware of what information is being collected.     * Used to build user profiles for targeted advertising.     * Vulnerability to theft if a device is compromised, potentially leading to identity theft or fraud.

• Positive User Experience (UX):     * Maintains login status and user preferences.     * Saves shopping cart contents even if the user leaves the site.     * Provides relevant suggestions based on browsing history.

Digital Currency and Blockchain

• Digital Currency: Currency that exists exclusively in electronic form, used for online payments and electronic transfers.

• Blockchain:     * A digital ledger used to record digital currency transactions.     * Consists of a time-stamped series of records grouped into blocks.     * Blocks are linked in a permanent, unchangeable chain; data cannot be altered once recorded.

• Time-stamped: Indicates each record contains the exact date and time the transaction occurred.

• Tracking Process:     1. Transaction is made.     2. Transaction is grouped into a block with others.     3. Block is time-stamped and linked to the previous block.     4. The new block is added to the blockchain, creating a permanent record.

Cyber Security Threats: Processes and Aims

• Brute-Force Attack:     * Process: Automated software repeatedly attempts different passwords or keys.     * Aim: Unauthorised access to accounts or encrypted data.     * Prevention: Strong passwords, two-step verification, firewalls to block repeat attempts.

• Data Interception:     * Process: Capturing data as it travels across an insecure network.     * Aim: Stealing private info like passwords or financial records.     * Prevention: SSL (HTTPS) encryption, firewalls, proxy servers.

• Distributed Denial of Service (DDoS):     * Process: Numerous compromised devices flood a server with requests simultaneously.     * Aim: Overload systems to make services unavailable to legitimate users.     * Prevention: Proxy servers, firewalls with filtering rules.

• Hacking:     * Process: Exploiting vulnerabilities or weak passwords to gain unauthorised access.     * Aim: Stealing, changing, or destroying data.     * Prevention: Biometrics, two-step verification, automated software updates.

Malware Categories

• Virus: Attaches to files; spreads when files are executed. Aim: Damage systems or steal data.

• Worm: Self-replicating; spreads across networks automatically without needing a host file. Aim: Disrupt operations.

• Trojan Horse: Disguises as legitimate software; tricked user installs it. Aim: Gain unauthorised access.

• Spyware: Secretly monitors activity (keystrokes/browsing). Aim: Steal passwords and personal details.

• Adware: Automatically displays unwanted ads; often bundled with other apps. Aim: Generate revenue or marketing data.

• Ransomware: Encrypts user files and demands payment for the decryption key. Aim: Extortion.

Deceptive Attacks: Pharming, Phishing, and Social Engineering

• Pharming:     * Process: Redirects user from a real site to a fake one by changing DNS settings or exploiting vulnerabilities.     * Aim: Steal login/financial details.

• Phishing:     * Process: Sending fake emails or links appearing to be from trusted sources.     * Aim: Trick users into revealing sensitive data.

• Social Engineering:     * Process: Manipulating human behavior to bypass technical security (e.g., tricking someone into revealing a password).     * Aim: Exploit human psychology rather than technical flaws.

Security Solutions and Defensive Strategies

• Access Levels: Restrict user actions (e.g., read-only vs. administrative) to prevent data misuse.

• Anti-malware: Scans and removes viruses, worms, and spyware.

• Authentication:     * Username/Password: Standard credentials.     * Biometrics: Unique physical features (facial recognition, fingerprints).     * Two-step verification: Requires a secondary code sent to a mobile device.

• Automated Software Updates: Installs security patches automatically to close vulnerabilities.

• Communication Auditing: Checking for unusual spelling, grammar, or tone in messages/links to identify phishing.

• Privacy Settings: Limiting personal information visibility on apps and websites.

Network Infrastructure: Firewalls and Proxy Servers

• Firewalls:     * Monitors incoming/outgoing traffic against security rules.     * Maintains logs and uses whitelists/blacklists.     * Can be hardware-based (router) or software-based (installed on device).

• Proxy Servers:     * Intermediary between user and Internet.     * Hides user IP address and filters content.

• Comparison (Firewall vs. Proxy Server):     * Firewall: Monitors traffic; uses security rules to block connections; protects network from unauthorized access.     * Proxy Server: Acts as an intermediary; forwards requests; hides IP addresses; filters web content.

Secure Socket Layer (SSL) and Scenario Analysis

• Definition: A protocol that encrypts data between a browser and a website, identified by https in the address bar.

• Scenario (Art Gallery Website):     * Process:         1. Gallery server sends a digital certificate to the browser.         2. Certificate contains the public key.         3. Browser encrypts data with the public key.         4. Server decrypts data using its private key.     * Security Logic: Even if data is intercepted, it is unreadable without the private key, ensuring protection for payment and personal details.