During an interview focusing on web application security, you may face questions such as:

• What are some common vulnerabilities in web applications?
• How do you mitigate risks associated with these vulnerabilities?
• Can you provide examples of how these vulnerabilities have been exploited in the past?

These questions are designed to assess your knowledge of identifying, understanding, and mitigating common vulnerabilities in web applications.

Understanding the following vulnerabilities is crucial as they represent the most common attacks that web applications are likely to face.

• SQL Injection: An attack that allows malicious SQL statements to control a database. Why it's important: It can result in unauthorized viewing of data, deleting data, or even gaining system-level access.
• Cross-Site Scripting (XSS): An attack in which malicious scripts are injected into otherwise benign and trusted websites. Why it's important: It can lead to session hijacking, defacement, or inserting malicious content.
• Cross-Site Request Forgery (CSRF): An attack that forces a user to execute unwanted actions on a web application in which they are currently authenticated. Why it's important: It can compromise end-user data and operations.

Understanding how to mitigate these threats is critical in securing web applications.

• SQL Injection: Use parameterized queries and prepared statements to prevent attackers from executing arbitrary SQL code.
• Cross-Site Scripting (XSS): Employ proper input validation and output encoding to ensure that injected scripts are not executed.
• Cross-Site Request Forgery (CSRF): Use anti-CSRF tokens to ensure that browser requests are legitimate.

Understanding how these vulnerabilities have been exploited provides context and reinforces the importance of preventive measures.

• SQL Injection: The Equifax breach, where attackers exploited an unpatched vulnerability, leading to a massive data breach affecting millions.
• Cross-Site Scripting (XSS): The MySpace Samy worm, which propagated itself by exploiting an XSS vulnerability, compromising over one million accounts.
• Cross-Site Request Forgery (CSRF): The GitHub CSRF vulnerability that allowed attackers to add SSH keys to user accounts, potentially compromising repositories.

Here are some follow-up questions you might encounter and how to respond effectively:

What Are the Differences Between SQL Injection and XSS?

SQL Injection involves manipulating a database via malicious SQL queries, potentially leading to unauthorized data access or system control. XSS, on the other hand, involves injecting malicious scripts into web pages, which can result in session hijacking or data theft.

How Would You Prioritize Fixing Multiple Vulnerabilities Discovered in a Web Application?

Typically, I would prioritize based on the severity and exploitability of the vulnerabilities. High-severity vulnerabilities such as SQL Injection and XSS, which can result in significant data breaches or compromised user accounts, would be prioritized first. Additionally, vulnerabilities that have been actively exploited in the wild would take precedence.

Can You Explain a Scenario Where CSRF Could Be Particularly Damaging?

A particularly damaging CSRF scenario could involve a banking application where an attacker tricks a logged-in user into transferring funds to the attacker's account without the user's knowledge or consent. This could result in financial loss and a breach of trust in the application's security.

By mastering these concepts and responses, you will be well-equipped to articulate your understanding of common web application vulnerabilities and mitigation strategies during an interview.