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9618 · 6.1

Data Security — practice questions

Practice and worked examples for 9618 Data Security. Short previews only — attempt the full question in MarkScheme against the official scheme.

Worked example 1

A college stores sensitive student data, including addresses and grades, on its network. Identify two distinct types of security threat the college faces and, for each threat, describe a specific measure to help prevent it. [4 marks]

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A good answer will identify a threat and link it to a specific, appropriate countermeasure.

Threat 1: Phishing attack targeting staff members. [1] An attacker could send an email pretending to be from the IT department, asking staff to 'verify' their login details on a fake website, thereby stealing their credentials.

Prevention 1: Implement regular staff training. [1] Educate staff on how to identify phishing emails (e.g., checking sender addresses, looking for poor grammar, hovering over links before clicking) and establish a clear policy for reporting suspicious emails.

Threat 2: A student introducing a virus via a USB stick. [1] A student could unknowingly bring a virus-infected USB from home and plug it into a college computer, allowing the malware to spread across the network.

Prevention 2: Implement a device control policy and use anti-virus software. [1] Configure college computers to automatically scan any removable media for malware upon connection. Alternatively, disable USB ports on non-essential computers and provide a secure method for file transfer.

Worked example 2

An e-commerce website needs to securely transmit a customer's credit card details from their browser to the website's server. The process uses both asymmetric and symmetric encryption. Explain why both types of encryption are used in this scenario. [6 marks]

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This question tests your understanding of the practical application of different encryption types.

Asymmetric Encryption's Role:

  1. Asymmetric encryption is used first to solve the key-sharing problem. [1] The web server has a public key (which it sends to the customer's browser) and a private key (which it keeps secret). [1]
  2. The customer's browser uses the server's public key to encrypt a newly generated symmetric key. [1] Because it's encrypted with the public key, only the server's corresponding private key can decrypt it, ensuring the symmetric key is transmitted securely.

Symmetric Encryption's Role: 3. Symmetric encryption is used for the actual transmission of the credit card data. [1] 4. This is because symmetric encryption is much faster and more computationally efficient than asymmetric encryption, making it suitable for encrypting the bulk of the data in the transaction. [1]

Conclusion: 5. This hybrid approach combines the security of asymmetric encryption for key exchange with the speed of symmetric encryption for data transfer, providing a secure and efficient solution. [1]