Why security must be designed in in HLD - Quick Recap

Recall & Review

beginner

What does it mean to 'design security in' a system?

It means planning and building security features from the start, not adding them later. This helps prevent risks and makes the system safer.

beginner

Why is adding security after development often problematic?

Because it can be costly, cause delays, and may not cover all vulnerabilities. Fixing security later is like patching holes in a boat after it starts leaking.

beginner

Name one real-life example that shows why security must be designed in.

A bank building with strong locks and cameras from the start is safer than adding them after a robbery. Similarly, systems need security from the beginning.

intermediate

How does designing security in improve system scalability?

It ensures security measures grow with the system, avoiding weak points as the system gets bigger and more complex.

intermediate

What are some risks of ignoring security in the design phase?

Risks include data breaches, loss of user trust, legal penalties, and expensive fixes later.

Why should security be included during system design?

A To avoid writing documentation

B To prevent vulnerabilities early

C To make the system slower

D To save money on hardware

Including security early helps prevent vulnerabilities and reduces risks.

What is a common problem when adding security after development?

A It may miss critical vulnerabilities

B It improves user experience

C It is cheaper and faster

D It reduces system complexity

Adding security late can miss important vulnerabilities and cause delays.

Which analogy best explains designing security in early?

A Building a house without doors

B Painting walls after furniture

C Locking doors after a burglary

D Installing locks before moving in

Installing locks before moving in is like designing security early.

What risk increases if security is ignored in design?

A Data breaches

B Faster development

C Lower costs

D Better performance

Ignoring security can lead to data breaches and other risks.

How does designing security in affect system scalability?

A It makes scaling impossible

B It limits growth

C It ensures security scales with system

D It has no effect

Designing security in helps security grow as the system scales.

Explain why security must be designed into a system from the beginning.

Think about fixing problems before they happen.

Describe the risks of adding security only after system development is complete.

Consider what happens if you patch a leaking roof after a storm.

Practice

1. Why is it important to include security in the system design from the beginning?

easy

A. Because security slows down the system and should be avoided

B. Because security can be added easily after development

C. Because users do not care about security

D. Because fixing security issues later is more expensive and risky

Solution

1. Step 1: Understand the cost of late security fixes

   Fixing security problems after the system is built often requires rework, causing delays and higher costs.

2. Step 2: Recognize the risk of ignoring early security

   Ignoring security early can lead to data breaches and loss of user trust, which are costly and damaging.

3. Final Answer:

   Because fixing security issues later is more expensive and risky -> Option D

4. Quick Check:

   Early security design = Cost saving and risk reduction [OK]

Hint: Security early saves cost and risk later [OK]

Common Mistakes:

• Thinking security can be added easily after development
• Assuming users don't care about security
• Believing security always slows down systems

2. Which of the following is a correct security design practice to include from the start?

easy

A. Encrypting sensitive data during storage and transmission

B. Ignoring authentication to speed up development

C. Using default passwords for all users

D. Allowing open access to all system components

Solution

1. Step 1: Identify secure data handling methods

   Encrypting data protects it from unauthorized access both when stored and during communication.

2. Step 2: Eliminate insecure options

   Ignoring authentication, using default passwords, or open access are insecure and expose the system to attacks.

3. Final Answer:

   Encrypting sensitive data during storage and transmission -> Option A

4. Quick Check:

   Encryption = Secure data handling [OK]

Hint: Encrypt data to protect it always [OK]

Common Mistakes:

• Skipping authentication for speed
• Using default or weak passwords
• Allowing unrestricted access

3. Consider a system designed without early security measures. What is the likely outcome when a data breach occurs?

medium

A. The breach causes loss of user trust and costly fixes

B. The breach improves system performance

C. The breach has no effect if data is public

D. The system can quickly fix the breach without impact

Solution

1. Step 1: Understand consequences of data breaches

   A data breach exposes sensitive information, damaging user trust and requiring expensive fixes.

2. Step 2: Reject incorrect outcomes

   Quick fixes without impact are unrealistic; breaches never improve performance; public data assumption is unsafe.

3. Final Answer:

   The breach causes loss of user trust and costly fixes -> Option A

4. Quick Check:

   Data breach = Trust loss + Costly fixes [OK]

Hint: Breaches cost trust and money [OK]

Common Mistakes:

• Assuming breaches have no impact
• Thinking breaches improve performance
• Believing fixes are always quick and cheap

4. A system was built without authentication and encryption. What is the main security flaw to fix?

medium

A. Disable logging to improve speed

B. Add authentication and encrypt data communication

C. Remove all user access controls

D. Use default passwords for all users

Solution

1. Step 1: Identify missing security features

   Authentication verifies users; encryption protects data in transit. Both are essential for security.

2. Step 2: Exclude harmful fixes

   Removing access controls, disabling logging, or using default passwords worsen security risks.

3. Final Answer:

   Add authentication and encrypt data communication -> Option B

4. Quick Check:

   Authentication + Encryption = Secure system [OK]

Hint: Add auth and encryption to fix security [OK]

Common Mistakes:

• Removing access controls
• Disabling logs to speed up
• Using default passwords

5. You are designing a new online service. Which approach best ensures security is built in from the start?

hard

A. Focus on features first; security can be patched later

B. Add security features only after the system is fully developed

C. Plan authentication, encryption, and secure communication before coding

D. Use default settings and rely on network firewalls only

Solution

1. Step 1: Recognize best security design practice

   Planning authentication, encryption, and secure communication early integrates security deeply and reduces risks.

2. Step 2: Understand risks of delayed security

   Adding security late or relying only on firewalls leaves many vulnerabilities and increases costs.

3. Final Answer:

   Plan authentication, encryption, and secure communication before coding -> Option C

4. Quick Check:

   Early security planning = Strong protection [OK]

Hint: Design security features before coding [OK]

Common Mistakes:

• Delaying security until after development
• Relying only on network firewalls
• Ignoring security to speed up features