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Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

Went through a security engineer screen at Google and got hit with a foundational security concept question. Pretty standard stuff but worth knowing cold.

Questions Asked (1)

Q1

What is the principle of least privilege?

Technical Trade-offsSystem Design
Author's notes

Knew this one but stumbled a bit trying to make it sound more sophisticated than it is.

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AI HintsAI Generated

Suggested Approach

Start with a clear, concise definition of the principle of least privilege (PoLP). Then, explain its importance in system design and security, and provide concrete examples of how it can be implemented in practice. Finally, discuss trade-offs and how to balance security with usability.

Pro tip: Emphasize that PoLP is not just about security but also about reducing blast radius and improving system resilience. Mention how Google implements PoLP internally (e.g., Borg's job-level isolation) to show alignment with the company's practices.

1. Define the Principle

State that PoLP means giving users, processes, or systems only the minimum permissions necessary to perform their tasks, and no more.

2. Explain Its Importance

Discuss how PoLP reduces attack surface, limits damage from breaches, and simplifies auditing and compliance.

3. Provide Implementation Examples

Give concrete examples such as role-based access control (RBAC), IAM policies, container permissions, and API scopes.

4. Discuss Trade-offs

Acknowledge challenges like increased complexity, potential for over-restriction, and the need for dynamic privilege management.

5. Relate to System Design

Explain how PoLP influences architecture decisions, such as microservices with isolated permissions, and zero-trust security models.

Key Points to Mention

  • Definition: minimum necessary access rights
  • Security benefits: reduced attack surface, limited blast radius
  • Implementation mechanisms: RBAC, IAM, ACLs, capability-based security
  • Trade-offs: complexity, management overhead, potential for friction
  • Real-world examples: Google's BeyondCorp, AWS IAM policies, Unix file permissions
  • Relation to zero-trust and defense in depth

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.