How I Prepared for My Amazon Security Engineer (L4) Interview

I interviewed for a security engineer (L4) position at Amazon during my job search as a recent graduate in 2021. I was fortunate enough to receive an offer, and I spent a year in that role before transitioning to a software engineer (SWE) position internally. In this article, I will share my preparation strategies for the security engineer interview, focusing on two main areas: technical knowledge and behavioral skills.

Security Knowledge

I found Glassdoor to be a valuable resource for understanding the types of interview questions asked at various companies, particularly regarding common security queries.

These lists formed the core of my study materials. Prior to interviewing at Amazon, I had completed a 10-week cybersecurity research internship during my sophomore summer, which gave me a solid grounding in cryptography, various cyberattacks, and general security principles. I encountered several unfamiliar concepts, such as CSRF, and, with limited time before my final round, I concentrated on reviewing topics I was already familiar with.

Here’s a summary of what I focused on, including some additional topics not shown in the Glassdoor lists:

Cryptography Essentials

1. Symmetric vs. Asymmetric Encryption: Recognizing which is faster and understanding the unique problem solved by asymmetric cryptography is crucial.
2. Hashing: Familiarity with key properties (non-reversibility, avalanche effect, etc.) and the distinctions between hashing and encryption, as well as the implications of hashing passwords.
3. Salt and Pepper: Understanding the roles and storage methods of both.
4. Transport Layer Security (TLS): Knowledge of its function, handshake steps, and the distinction between TCP and UDP.
5. Advanced Encryption Standard (AES): Familiarity with AES modes and their security implications.
6. Cryptographic Keys: Understanding key strength and the importance of key derivation functions.
7. Types of Encryption: Differentiating between payload, in-transit, and at-rest encryption.
8. Common Cyberattacks: Being aware of password attacks, SQL injection, and denial-of-service attacks.

General Security Concepts

1. Perfect Security: There is no such thing; the weakest link often lies with the user.
2. Security via Obscurity: While it can offer some protection, it should not be relied upon solely.
3. Continuous Evolution: Security engineers must constantly adapt as hackers find new ways to exploit systems.
4. Avoiding Over-Engineering: Excessive security measures can lead to performance issues and poor user experiences.
5. Layered Security: A multi-faceted approach to security is essential.

In preparation for the interview, I revisited many of the cryptography topics, as they are fundamental to security and often appear in discussions. I also refreshed my knowledge of cyberattacks and important concepts related to hashing, as they are integral to many cryptographic algorithms.

Coding Skills

I was unsure if there would be a coding section in my security engineer interview. However, after researching online, it became clear that coding questions were common, especially within tech companies like Amazon. I anticipated a traditional LeetCode-style problem-solving format, which typically requires coding a solution in 30-45 minutes while explaining thought processes and analyzing time and space complexity.

Over the course of a year, I had prepared for coding interviews, focusing on LeetCode problems. However, my preparation for this specific interview was brief, spanning only two weeks, during which I attempted around 50-60 problems.

General Computer Science Concepts

With the breadth of topics covered in tech interviews, I brushed up on fundamental computer science principles, including:

1. Networking: Understanding TCP/IP layers, IP addresses, and DNS.
2. Object-Oriented Programming: Familiarity with abstract classes and interfaces.
3. Miscellaneous Concepts: Knowing the implications of upcasting/downcasting and the characteristics of good unit tests.