AppSec interview questions?

Question

I am preparing for a technical interview for an AppSec pen-testing position. For those of you that have had AppSec positions, what sharp-shooter questions do you think I can expect? What questions would you ask a candidate if you were doing the interview? Thank you for your insight!

Answer 1

Scenario-Based Questions

1. Blind Testing:
2. You only have a URL and no documentation. How would you approach testing the application for vulnerabilities?
3. Pen-Testing a Login Flow:
4. You’re tasked with testing an application’s login functionality. What vulnerabilities would you test for?
5. Exploiting File Upload Functionality:
6. The application allows users to upload files. How would you test for security issues?
7. API Token Leakage:
8. You suspect that API tokens are being leaked in client-side JavaScript. How would you confirm this?
9. Securing WebSockets:
10. How would you test WebSockets for security vulnerabilities?

How to respond with SMART:

The SMART framework ensures your responses are clear, well-structured, and impactful during an interview. Let’s break down each part further with an emphasis on how to best apply it to your answers, especially for AppSec or technical pen-testing roles.

1. S – Specific

Focus on describing the exact situation or task you were handling. Avoid generalities.

1. What was the context?
2. Who was involved?
3. What was the problem or challenge?

In technical interviews, being specific often means identifying the:

1. Target system or application type (e.g., a login endpoint, API, or mobile app).
2. Vulnerability or security gap (e.g., SQL Injection, XSS, CSRF).

Example from earlier:

“During a web application pen test for a financial client, I identified a SQL Injection vulnerability in the login endpoint.”

2. M – Measurable

Quantify the results or scope of the situation. Numbers add credibility and help interviewers understand the impact of your actions.

1. How severe was the issue? (e.g., “15,000 user records were exposed”)
2. How quickly did you resolve the problem? (e.g., “4 hours to report, 48 hours to verify”)
3. What impact did your solution have? (e.g., “Prevented potential data breaches”)

This is critical in AppSec roles, where demonstrating measurable outcomes—like the number of vulnerabilities identified, the risk mitigated, or time saved—shows your value.

Example:

“I confirmed the vulnerability allowed full access to over 15,000 user records containing sensitive PII.”

3. A – Actionable

This is the meat of your response. Focus on the actions you took to solve the problem. Highlight:

1. The steps you took to identify, validate, and report the issue.
2. How you collaborated with others, if necessary.
3. Tools or methods used (e.g., Burp Suite, manual testing, API fuzzing).

Key tip: Keep the focus on your contributions, even if you worked as part of a team.

Example:

“I replicated the issue in a test environment, documented the vulnerability in a detailed report, and provided developers with secure coding recommendations, such as implementing parameterized queries.”

4. R – Relevant

Connect your example directly to the role or skill set the interviewer is looking for. In this case, emphasize:

1. Your ability to identify and address vulnerabilities effectively.
2. Your knowledge of AppSec concepts, tools, and best practices.
3. Your ability to communicate findings and solutions to stakeholders.

Key tip: Always relate your actions to broader AppSec goals, such as preventing breaches, improving system security, or mitigating risk.

Example:

“This aligned with my role as an Application Security specialist, where my primary goal is to secure systems and prevent unauthorized access to sensitive data.”

5. T – Time-bound

Include the timeline to showcase your efficiency and sense of urgency. Interviewers love to see that you can work under deadlines while maintaining quality.

1. How quickly did you identify the issue?
2. How long did it take to resolve or verify the fix?

Example:

“Within 4 hours, I reported the issue to stakeholders and ensured the vulnerability was remediated within 48 hours.”

Pulling It All Together

Here’s the complete SMART-based answer again with explanations inline:

"During a web application pen test for a financial client (Specific), I identified a critical SQL Injection vulnerability in the login endpoint that allowed unauthorized access to over 15,000 user records containing sensitive PII (Measurable). I immediately replicated the issue in a test environment, documented it in a step-by-step report, and provided the developers with secure coding recommendations, such as using parameterized queries (Actionable). This aligned with my role as an Application Security specialist, where my primary goal is to secure applications and prevent breaches (Relevant). Within 4 hours, I reported the issue, and I verified that the remediation was successfully implemented within 48 hours (Time-bound)."