Module 5: Encryption and Decryption PDF

DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE...

DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 68 Module 5: ENCRYPTION AND DECRYPTION Objectives At the end of the chapter, the students would be able to: Gain knowledge and understanding of the methods of attacks. INTRODUCTION In a network, attackers may employ various methods to gain unauthorized access, disrupt operations, or steal sensitive data. These methods are known as network attacks, and they can range from simple reconnaissance to sophisticated exploits. Network attacks are malicious actions taken by attackers to disrupt, compromise, or exploit the integrity, confidentiality, and availability of a network. These attacks can target any part of a network, including the devices, communication protocols, servers, or data. METHODS OF ATTACKS Below are the most common types of network attacks and how they work: 1. Denial of Service (DoS) and Distributed Denial of Service (DDoS) Attacks Denial of Service (DoS): The attacker aims to overwhelm a system, server, or network with excessive traffic or requests, causing it to become slow, unresponsive, or completely unavailable. o Example: Flooding a website with HTTP requests or ping packets (ICMP floods). Distributed Denial of Service (DDoS): A more advanced form of DoS, where the attack comes from multiple sources (often botnets or infected devices), making it harder to block. o Example: Botnets launching simultaneous attacks from thousands of compromised machines. 2. Man-in-the-Middle (MITM) Attacks In MITM attacks, the attacker intercepts and potentially alters the communication between two parties without their knowledge. Example: An attacker may intercept messages between a user and a website, allowing them to read or modify the transmitted data. Common MITM attacks: o Eavesdropping: Monitoring the data transmitted between two parties. o Session Hijacking: Stealing a session token to impersonate the user. o SSL Stripping: Downgrading a secure HTTPS connection to an unencrypted HTTP one. 3. Phishing and Spear Phishing Phishing: A deceptive attempt to obtain sensitive information (like usernames, passwords, or credit card details) by pretending to be a trustworthy entity in electronic communications (usually email). CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 69 o Example: An email that appears to be from a bank asking the recipient to click a link and enter their account details on a fake website. Spear Phishing: A more targeted version of phishing where the attacker customizes the attack for a specific individual or organization, often using personal information to increase the likelihood of success. o Example: An attacker impersonating a CEO asking an employee to transfer funds to a particular bank account. 4. Password Attacks Attackers often attempt to crack or bypass passwords to gain unauthorized access to systems and networks. Common password-based attacks include: Brute Force Attack: Trying every possible combination of characters until the correct password is found. Dictionary Attack: Using a precompiled list of likely passwords (such as common words or phrases) to guess the correct one. Credential Stuffing: Using stolen username/password pairs from previous data breaches to attempt login on other websites, assuming people reuse passwords. Keylogging (Keystroke Logging): Malicious software or hardware devices record keystrokes to capture sensitive information, like passwords or personal details. 5. Spoofing Attacks IP Spoofing: The attacker sends packets from a fake IP address, making it appear as if they are coming from a legitimate source. MAC Spoofing: The attacker changes the Media Access Control (MAC) address of their network interface card (NIC) to impersonate another device on the network. Email Spoofing: The attacker sends emails that appear to come from a trusted source but are actually from a malicious actor. 6. SQL Injection In an SQL injection attack, the attacker injects malicious SQL code into a vulnerable web application’s database query, allowing them to manipulate the database (view, modify, or delete data) or even execute administrative operations. Example: An attacker submits a malicious SQL statement through an input field, which is executed by the database, potentially exposing sensitive data. 7. Cross-Site Scripting (XSS) In XSS attacks, malicious scripts are injected into webpages viewed by users. These scripts can steal information, redirect users, or perform actions on their behalf. Stored XSS: The malicious script is stored on the web server and executed when the webpage is loaded by a user. Reflected XSS: The script is reflected off a web server in the response to a request, often as part of a URL. 8. Session Fixation In a session fixation attack, the attacker forces a user's session ID to a known value. The attacker can then hijack the session once the user logs in and takes over their session. Example: The attacker sends the user a link with a session ID set in the URL. After the user logs in, the attacker can use that session ID to impersonate the user. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 70 9. DNS Spoofing (Cache Poisoning) DNS Spoofing or Cache Poisoning involves sending false DNS records to a DNS resolver, causing it to return incorrect IP addresses for domain names. This can lead users to malicious websites, enabling attacks like phishing, malware distribution, or information theft. Example: A user types in a legitimate website address, but due to DNS poisoning, they are redirected to a malicious site instead. 10. Privilege Escalation In a privilege escalation attack, an attacker gains higher-level access to a system than they are authorized to have, allowing them to perform actions that would normally be restricted. Privilege escalation can be classified into two types: Vertical Privilege Escalation: Gaining higher privileges within the same system (e.g., normal user becoming an administrator). Horizontal Privilege Escalation: Gaining access to the same level of privileges but on a different account (e.g., accessing a colleague's account). 11. Evil Twin Attacks In an Evil Twin Attack, an attacker sets up a fake wireless access point with the same SSID (name) as a legitimate network. Unsuspecting users may connect to this "evil twin" instead of the legitimate network, allowing the attacker to intercept data, inject malware, or steal credentials. 12. Rogue Device Attacks This attack occurs when an attacker connects an unauthorized device to a network, often bypassing security controls like firewalls and intrusion detection systems. Example: An attacker connects a rogue access point to a network to capture data from connected devices or inject malicious traffic into the network. 13. ARP Spoofing (ARP Poisoning) In ARP Spoofing, the attacker sends fake Address Resolution Protocol (ARP) messages to associate their MAC address with the IP address of another device on the network. This allows the attacker to intercept traffic intended for another device, facilitating MITM attacks or data theft. 14. Cryptojacking Cryptojacking is a type of attack where the attacker uses the victim's computing resources to mine cryptocurrency without their consent. This can be done through malicious scripts embedded in websites or malware installed on devices. 15. Social Engineering Attacks These attacks rely on manipulating human behavior to gain access to systems, data, or physical locations. Pretexting: The attacker creates a false sense of trust by impersonating someone who is authorized to access information. Baiting: The attacker offers something enticing, such as free software or a prize, to get the victim to download malicious software or give away sensitive information. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 71 COUNTERMEASURES FOR VARIOUS NETWORK ATTACKS Network attacks come in many forms and can target individuals, businesses, or entire systems. Countermeasures for network attacks are essential for protecting the confidentiality, integrity, and availability of data and systems within a network. Effective network security requires a combination of proactive defenses (such as firewalls, encryption, and intrusion detection systems) and educating users about potential threats (like phishing and social engineering). By understanding the various types of network attacks, organizations and individuals can better prepare to prevent, detect, and respond to cyber threats. Here’s an overview of the countermeasures for various common network attacks: 1. Denial of Service (DoS) and Distributed Denial of Service (DDoS) Attacks Description: DoS and DDoS attacks overwhelm a target system with traffic to exhaust its resources and make it unavailable to legitimate users. Countermeasures: Firewalls and Intrusion Prevention Systems (IPS): Configure firewalls to filter malicious traffic based on signatures, IP addresses, or rates. DDoS Mitigation Services: Use third-party DDoS protection services like Cloudflare, AWS Shield, or Akamai to absorb large amounts of attack traffic. Rate Limiting: Implement rate limiting to restrict the number of requests a user can make to the server within a specified time. Traffic Scrubbing: Route traffic through a scrubbing center to filter malicious packets before they reach your server. Anycast Routing: Distribute network traffic to multiple data centers using Anycast, helping to disperse the attack load. 2. Man-in-the-Middle (MITM) Attacks Description: An attacker intercepts and potentially alters communication between two parties without their knowledge. Countermeasures: Encryption: Use SSL/TLS (HTTPS) to encrypt data in transit and prevent interception or tampering by attackers. VPN (Virtual Private Network): Utilize a VPN to secure communication between endpoints, especially on public or unsecured networks. Public Key Infrastructure (PKI): Use digital certificates for strong authentication, ensuring that users and systems communicate with legitimate parties. HSTS (HTTP Strict Transport Security): Enforce secure connections to prevent attackers from downgrading secure HTTPS connections to insecure HTTP connections. 3. Phishing and Spear Phishing Attacks Description: CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 72 Phishing involves tricking users into revealing sensitive information (e.g., passwords, credit card numbers) by impersonating legitimate entities. Spear Phishing is a more targeted form of phishing where attackers use specific details about the victim to craft convincing attacks. Countermeasures: Email Filtering: Use spam filters to block suspicious emails, and implement anti-phishing filters to detect phishing links. Multi-Factor Authentication (MFA): Require MFA for accessing sensitive systems or services, so even if credentials are compromised, attackers cannot gain access. User Education: Train employees and users to recognize phishing attempts, such as spotting suspicious email addresses, unusual requests, and malicious links. Anti-Phishing Software: Use browser extensions or anti-phishing software that warns users of suspicious websites and email attachments. 4. Password Attacks Description: Attackers attempt to guess or crack passwords using techniques like brute force, dictionary attacks, or credential stuffing. Countermeasures: Strong Password Policies: Enforce the use of complex passwords (long passwords with a mix of characters) and password expiration. Rate Limiting and Account Lockout: Implement rate limiting and account lockout mechanisms after several failed login attempts to prevent brute force attacks. Multi-Factor Authentication (MFA): Use MFA (e.g., a combination of passwords and one- time codes sent via email/SMS) to add an additional layer of security. Password Hashing: Use secure hashing algorithms like bcrypt, PBKDF2, or Argon2 to store passwords securely, ensuring that even if the database is compromised, passwords are not easily recovered. Password Managers: Encourage users to use password managers to generate and store strong, unique passwords for each service. 5. Spoofing Attacks Description: IP Spoofing, MAC Spoofing, and Email Spoofing involve attackers pretending to be someone else by falsifying information such as their IP address, MAC address, or email header. Countermeasures: IP Spoofing Mitigation: Use Ingress and Egress Filtering at the network perimeter to block packets with invalid or spoofed IP addresses. MAC Address Filtering: Implement MAC address filtering on wireless networks to only allow trusted devices to connect. Email Authentication: Implement SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) to prevent email spoofing and improve email authentication. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 73 Secure Email Gateways: Use anti-spoofing and anti-spam filters on mail servers to detect and block spoofed emails. 6. SQL Injection Description: SQL Injection is an attack where malicious SQL code is inserted into an input field to execute arbitrary queries on the backend database, often leading to unauthorized access to or manipulation of data. Countermeasures: Input Validation and Sanitization: Always sanitize user inputs and validate them to ensure they contain no executable SQL code (e.g., escape special characters). Parameterized Queries: Use prepared statements and parameterized queries to separate user input from the SQL code, preventing injection. Web Application Firewalls (WAF): Deploy a WAF to monitor and block malicious SQL injection attempts. Least Privilege Access: Ensure the database account used by the application has least privilege, i.e., only the minimum required permissions to perform necessary actions. 7. Cross-Site Scripting (XSS) Description: XSS allows attackers to inject malicious scripts (usually JavaScript) into web pages, which are executed in the context of the user's browser, often leading to data theft or defacement. Countermeasures: Input Sanitization and Output Encoding: Always sanitize inputs to prevent malicious scripts from being injected into web pages and encode outputs to render any potential script tags as harmless. Content Security Policy (CSP): Implement CSP to restrict the types of content that can be executed on a webpage, helping to mitigate XSS attacks. HttpOnly Cookies: Set the HttpOnly flag for cookies to prevent JavaScript from accessing session cookies. X-XSS-Protection: Use browser features like X-XSS-Protection header to block reflected XSS attacks. 8. Session Hijacking Description: Session hijacking occurs when an attacker steals a session token (often from cookies or HTTP headers) and impersonates a user. Countermeasures: Secure Session Management: Use secure session management techniques such as regenerating session IDs after login, and setting secure and HttpOnly flags on cookies. SSL/TLS Encryption: Ensure that sensitive data, including session tokens, are transmitted over SSL/TLS to protect them from interception during transit. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 74 Session Timeouts: Implement session timeouts to automatically log users out after a certain period of inactivity. Multi-Factor Authentication (MFA): Use MFA to protect against session hijacking even if session tokens are compromised. 9. DNS Spoofing (Cache Poisoning) Description: DNS spoofing involves injecting malicious DNS records into a DNS resolver’s cache, redirecting users to malicious websites. Countermeasures: DNSSEC (DNS Security Extensions): Implement DNSSEC to cryptographically secure DNS data, ensuring that DNS responses are not tampered with. DNS Filtering: Use DNS filtering to block requests to known malicious domains or websites. Frequent DNS Cache Flushing: Regularly flush the DNS cache to remove potentially poisoned entries. Use Trusted DNS Servers: Use trusted, secure DNS providers or configure DNS resolvers to only accept queries from trusted sources. 10. Privilege Escalation Description: Privilege escalation attacks occur when an attacker gains elevated access to a system, often through exploiting vulnerabilities or misconfigurations. Countermeasures: Patch Management: Regularly apply patches and updates to all systems to fix known vulnerabilities that could lead to privilege escalation. Principle of Least Privilege (POLP): Ensure that users have only the minimum privileges necessary to perform their tasks. Role-Based Access Control (RBAC): Implement RBAC to manage access based on user roles, limiting their ability to escalate privileges. Regular Audits: Perform regular audits of user accounts, permissions, and access logs to detect any abnormal privilege escalation attempts. 11. Rogue Device Attacks Description: A rogue device is any unauthorized device connected to the network, such as a rogue access point or unauthorized USB device. Countermeasures: Network Access Control (NAC): Use NAC solutions to enforce security policies and ensure that only authorized devices are allowed to connect to the network. 802.1X Authentication: Use 802.1X authentication for network access control, requiring devices to authenticate before connecting. Wireless Intrusion Prevention System (WIPS): Implement a WIPS to detect and block rogue wireless access points and unauthorized devices. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 75 Endpoint Detection and Response (EDR): Use EDR solutions to monitor endpoint devices for signs of rogue activities or unauthorized device connections. 12. Cryptojacking Description: Cryptojacking occurs when an attacker uses a victim’s system resources to mine cryptocurrency without consent. Countermeasures: Ad Blockers and Anti-Malware: Use ad blockers and anti-malware tools that can detect and block cryptojacking scripts. Browser Extensions: Use browser extensions to block cryptojacking scripts (e.g., NoCoin). Regular Software Updates: Keep all software, browsers, and plugins up to date to reduce the risk of exploiting vulnerabilities for cryptojacking. Monitor System Resources: Regularly monitor CPU/GPU usage and network activity to detect unusual mining activities. SYNTHESIS Effective network security involves a multi-layered approach that combines preventive measures, such as encryption and access controls, with proactive defenses, such as monitoring and detection. Implementing these countermeasures across your network can significantly reduce the risk of attacks and strengthen your defense against cyber threats. CPE-DDC313: DATA AND DIGITAL COMMUNICATIONS PREPARED BY: JUVY C. GRUME, PCPE, MIT  DON HONORIO VENTURA STATE UNIVERSITY Bacolor, Pampanga COLLEGE OF ENGINEERING OLLEGE OF AND ARCHITECTURE NGINEERING AND RCHITECTURE Department of Computer Engineering 76 References Admin AfterAcademy. (2020, January 19). What are Data Transmission Modes in a network? [Online Article]. https://afteracademy.com/blog/what-are-the-data-transmission-modes-in-a- network Brain, M., Wilson, T.V., & Johnson B. (2001, April 13). 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