Network Security and Privacy Threats
ICT Core C5 - Interactive Study Guide
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Network Security Fundamentals
AAA Security Framework
The AAA framework consists of three key components:
Authentication (認證)
Verifying user identity through passwords, biometrics, or two-factor authentication.
Authorisation (授權)
Granting access rights such as read, write, or execute permissions and access control lists.
Accounting (帳號管理)
Logging activities, tracking resource usage, and maintaining audit trails.
Access Control Methods
Physical Access Control: Locks, security guards, biometric systems
Logical Access Control: Passwords, firewalls, encryption
Password Security Best Practices
- At least 8 characters
- Mixed combination: digits, uppercase, lowercase, special characters
- Avoid personal information, simple patterns, common words
- Change every 3 months, don't reuse last 3 passwords
- Never share or record passwords
Malware & Threats
Self-replicating malware that attaches to host files and activates when the host file runs. It can spread to other files and systems.
Self-replicating malware that spreads via networks without needing a host file. Consumes bandwidth and system resources.
Malware disguised as legitimate software that creates a backdoor for unauthorized access. Does NOT self-replicate.
Malware that encrypts files and demands ransom payment for the decryption key.
Software that secretly monitors user activities and collects personal data without consent.
Software that displays unwanted advertisements and may redirect browser to advertising websites.
Comparison: Virus vs Worm vs Trojan
| Feature | Virus | Worm | Trojan |
|---|---|---|---|
| Self-Replicates | Yes | Yes | No |
| Needs Host File | Yes | No | No |
| Spreads Via | File execution | Network | User installation |
Defense Mechanisms
Antivirus Software: Uses virus signatures for detection, performs real-time scanning, requires regular updates
Firewall: Monitors incoming and outgoing traffic, blocks unauthorized access
Network Attacks
Unauthorized interception of private communications to steal sensitive information.
Exploiting system vulnerabilities. Consequences include data theft, website vandalism, and creating zombie computers for botnets.
Manipulating people's trust to trick them into revealing confidential information. Methods include:
- Baiting: Offering something enticing
- Quid pro quo: Promising a benefit in exchange for information
- Catfishing: Creating fake online identities
- Pretexting: Creating fabricated scenarios
- Phishing: Fake emails or websites
Fraudulent emails or websites disguised as legitimate entities to steal credentials and sensitive information.
Attacker intercepts communication between two parties, copying passwords and credit card information before forwarding them. The communication appears normal, making detection difficult.
Flooding servers with excessive requests to make them unavailable. DDoS uses multiple compromised computers (botnets) to launch distributed attacks.
Hackers set up a fake Wi-Fi access point without password, often naming it after the location to disguise as a free hotspot. Once connected, hackers can intercept and monitor all network activity.
Sending large numbers of unsolicited messages via SMS or email. Most are commercial advertisements. May cause mailbox to exceed quota, forcing victims to spend time cleaning up and potentially paying for additional storage.
Protecting Online Privacy
Privacy Threats
Overexposed personal information on social media platforms
Excessive data collection by service providers
Protection Methods
Anonymous Browsing & Proxy Servers
Use proxy servers to hide your IP address and location from websites you visit.
Clear Browsing History & Cookies
Regularly delete browsing history and cookies, especially on public computers. Understand the difference between first-party and third-party cookies.
Turn Off Autofill
Disable browser autofill features to prevent automatic entry of sensitive information.
Private Browsing / Incognito Mode
Use private browsing mode which doesn't save history, cookies, or form data after the session ends.
Two-Factor Authentication
Enable two-factor authentication requiring two different types of verification (e.g., password + SMS code).
Wi-Fi & Network Protection
Encryption Protocols
WEP (有線等效加密): Older, less secure encryption protocol
WPA/WPA2: More secure protocols that replaced WEP, using stronger encryption algorithms
Wi-Fi Security Measures
- Hide Wi-Fi SSID to prevent network name from appearing in public scans
- Configure MAC address filtering to allow only approved devices
- Use strong WPA2 encryption with complex passwords
- Regularly update router firmware
Public Wi-Fi Risks
Many public places provide free Wi-Fi hotspots. When conducting privacy-related activities such as online banking or stock trading, avoid using public Wi-Fi networks. Hackers may intrude and monitor incoming and outgoing information on these open networks.
Virtual Private Network (VPN)
VPN establishes an encrypted "tunnel" between your device and the VPN server to transmit data securely. It protects data transmitted on the Internet and prevents unauthorized access.
Applications:
- Intranet virtual private network
- Remote access virtual private network
- Access WAN via VPN
Interactive Quiz
Flashcards
Exam Practice
Q1: Explain the difference between authentication and authorisation in the AAA framework. Give one example for each.
Authentication verifies identity (e.g., entering a password to log in), while authorisation determines what a verified user can do (e.g., read-only vs. read-write access to files).
Q2: Compare and contrast computer viruses, worms, and Trojan programs. Include how each spreads and whether they self-replicate.
Viruses attach to host files and self-replicate when the file runs. Worms self-replicate and spread via networks without a host file. Trojans disguise as legitimate software, create backdoors, but do NOT self-replicate.
Q3: Yuki received a suspicious email asking her to click a URL to reactivate her credit card. Even though she did not enter any bank details, what two potential threats could arise from clicking the link?
(1) The link may download malware (e.g., spyware or Trojan) onto her device. (2) The website may use cookies or scripts to track her browsing behaviour and collect personal information.
Q4: A school IT administrator uses a proxy server to record all URLs that students visit. Explain two benefits of using a proxy server in a school network and one potential privacy concern.
Benefits: (1) The proxy server can filter inappropriate web content, blocking harmful websites. (2) It can cache frequently visited pages to improve browsing speed. Privacy concern: Students' browsing activities are being monitored and recorded, which may infringe on their privacy rights.
Q5: John wants to improve the security of his home wireless network. Describe three different methods he can use and explain how each method enhances security.
(1) Use WPA2 encryption instead of WEP — WPA2 uses stronger encryption algorithms making it harder for hackers to crack. (2) Configure MAC address filtering — only allows devices with approved physical addresses to connect. (3) Hide the SSID — prevents the network name from appearing in public Wi-Fi scans, making it harder for unauthorized users to find.