Why security must be designed in in HLD - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why is it important to include security from the start in system design?

Consider a new web application project. Why should security be integrated during the initial design phase rather than added later?

A Because early security design helps prevent costly fixes and data breaches

B Because security features slow down development and should be avoided initially

C Because adding security later is cheaper and faster

D Because users do not care about security in early versions

💡 Hint

Think about the cost and impact of fixing security problems after the system is built.

Designing security early helps identify risks and build protections before vulnerabilities exist. Fixing security issues later can be expensive and damage trust.

❓ Architecture

intermediate

Which architectural approach best supports built-in security?

When designing a system, which architecture helps ensure security is integrated throughout?

A Monolithic architecture with no modular boundaries

B Single-tier architecture with all components tightly coupled

C Layered architecture with clear separation of concerns and security checks at each layer

D Architecture without authentication or authorization layers

💡 Hint

Think about how separating parts of a system can help control access and reduce risks.

Layered architecture allows security controls at each level, making it easier to enforce policies and isolate threats.

❓ scaling

advanced

What is a key risk of adding security features only after scaling a system?

A system has grown rapidly without security built in. What is a major risk when trying to add security after scaling?

A Adding security later may cause downtime and complex refactoring

B Security can be added easily without affecting performance

C Scaling automatically improves security by distributing load

D Users prefer systems without security features

💡 Hint

Consider the challenges of changing a large system's design after deployment.

Adding security late often requires major changes, risking downtime and errors, and increasing costs.

❓ tradeoff

advanced

What tradeoff occurs when security is not designed in from the start?

What is a common tradeoff when security is neglected during initial system design?

A Slower development and no impact on future costs

B Faster initial development but higher risk of breaches and costly fixes later

C Better user experience with no security concerns

D Lower risk of attacks because security is not visible

💡 Hint

Think about speed versus safety in software projects.

Skipping security early may speed up development but leads to vulnerabilities and expensive remediation later.

❓ estimation

expert

Estimate the cost impact of adding security after deployment versus during design

A company estimates fixing a security flaw during design costs $10,000. After deployment, the same fix costs 10 times more due to patching, testing, and reputation damage. What is the estimated cost after deployment?

A $1,000,000

B $50,000

C $10,000

D $100,000

💡 Hint

Multiply the initial cost by the factor given.

Fixing security issues after deployment is often 10 times more expensive due to extra work and impact.

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