Threats and Security on the Internet ：練習問題

What is the primary function of a firewall in network security?

In the context of accessing a secured online system, what is the fundamental difference between authentication and authorisation?

Imagine a situation where Eve wants to send a sensitive message to Frank over the Internet while allowing Frank to verify the sender's identity and ensure the message was not modified (i.e., its authenticity and integrity). They employ a public-key cryptographic system that provides both encryption and digital signing.
To achieve both confidentiality and authentication/integrity, what is the correct combination of keys Eve and Frank must use?

What is the main advantage of enabling Multi-Factor Authentication (MFA) for online accounts compared to using only a username and password?

A firewall is installed at the gateway of a school's computer network. Which of the following tasks is primarily performed by this firewall to enhance security?

What is the primary function of a firewall in the context of network security?

Identify the cyberattack that encrypts a user's files and demands payment for the decryption key, and explain why offline backups are more effective for recovery than cloud-synchronised backups in this specific scenario.

Distinguish between a Denial of Service (DoS) attack and a Distributed Denial of Service (DDoS) attack regarding the origin of traffic and the primary challenge for network filtering.

Mary is studying at a local coffee shop and connects her laptop to the café's free public Wi-Fi network to do her research. While browsing, she notices some unusual activities on her laptop and later receives an unsolicited email asking for her bank details, claiming to be from her internet service provider.

(a) Identify two potential network security threats Mary might be facing in this scenario.

(b) For one of the threats identified in part (a), explain an effective measure Mary can take to protect herself.

(c) Apart from network security threats, explain one common privacy concern associated with using online services and suggest one practical way for Mary to maintain her privacy.

A staff member at an accounting firm receives an email with an attachment named 'Invoice.exe'. After running the file, the computer becomes significantly slower, and the same email is automatically sent to all contacts in the staff member's address book without their knowledge.

(a) Identify the type of malware described (virus or worm) and justify your answer based on its method of propagation. (2 points)
(b) The firm uses a firewall. Explain how a firewall can be configured to help mitigate the impact of such malware after an infection has occurred. (2 points)