Top 30 Web Application Security Interview Questions and Answers [2025]

• 17 June, 2024
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If you are a trained professional who wants to start a career in an MNC as a Web Application Security interview questions and answers, you are at the right place. Here, you will get the most frequently asked questions in an interview accumulated for you.

After clearing your doubts, you can easily crack the interview at a vacant place. What are you waiting for? Let’s get started!

Top 30 Web Application Security Interview Questions and Answers

1. What is Web Application Security?

   Web application security is a subset of cybersecurity that seeks to protect web-based applications against threats that include, but are not limited to, unauthorized usage, attacks, data breaches, and any other form of exploitation. It includes the strategies, practices, skills, tools, and processes employed to protect web-based applications against loss of confidentiality, integrity, and availability of the data and services.

   Web application security has become essential due to the widespread use of web applications for business activities such as e-commerce, finance, and communication to safeguard sensitive user data and maintain reliability.

2. Explain the OWASP Top 10 web vulnerabilities.

Here are the OWASP Top 10 Web Vulnerabilities:

1. Injection (A01:2021),
2. Broken Authentication (A02:2021),
3. Sensitive Data Exposure (A03:2021),
4. XML External Entities (XXE) (A04:2021),
5. Broken Access Control (A05:2021),
6. Security Misconfiguration (A06:2021),
7. Cross-Site Scripting (XSS) (A07:2021),
8. Insecure Deserialization (A08:2021),
9. Using Components with Known Vulnerabilities (A09:2021), and
10. Insufficient Logging and Monitoring (A10:2021).

3. Differentiate between SQL injection and XSS attacks.

By inserting malicious SQL queries into a database through the input fields of a web application, SQL injection compromises the security of the database. When a hacker inserts harmful code into a website that other users view, it’s known as cross-site scripting (XSS) and can lead to various destructive acts, including defacement or session hijacking. Whereas XSS targets users’ browsers, SQL injection targets databases.

4. Describe common authentication mechanisms. Bonus: How do secure password hashing techniques contribute?

Typical methods of authentication consist of:

1. Username and Password: Users’ supply credentials are to be verified.
2. Multi-Factor Authentication (MFA): Other requirements, like a code from a mobile application, must be met to log in.
3. Social Login: Using their current social network identities and passwords, users log in.

Furthermore, to ensure the security of password-hashing procedures, I will remember that these approaches store passwords as one-way hashes, rendering them unreadable even in the unlikely case that an attacker gains access to the database.

These techniques add an extra degree of security by using random salts and strong hashing algorithms.

5. Explain DoS and CSRF attacks. (Bonus: How can web applications be protected?)

The goal of a denial-of-service attack (DoS) is to flood an online application with traffic such that legitimate users cannot access it. Conversely, Cross-Site Request Forgery, or CSRF, exploits a user’s logged-in session to carry out unauthorized activity on a website that is supposed to be trustworthy.

Furthermore, the online applications can be secured with the following techniques:

• DoS: Implementing rate limits, CAPTCHAs, and screening malicious traffic are all necessary.
• CSRF: CSRF tokens are used to validate requests and inform users about safe surfing behaviors.

6. Elaborate on input validation and output encoding for XSS prevention.

While output encoding converts potentially hazardous data into a safe format for display, preventing XSS attacks, input validation verifies that user inputs follow expected formats and types to prevent malicious data entry.

7. Explain the significance of SSL/TLS for secure communication.

By encrypting data being communicated between a client and a server, SSL/TLS guarantees safe communication by guarding against eavesdropping and manipulation.

8. Discuss the importance of secure coding practices and how SDLC promotes them.

Among the reasons secure coding techniques are important are:

• Vulnerability Prevention,
• Data Protection,
• Maintaining Trust,
• Cost Reduction,
• Compliance Requirements,
• Business Continuity, and
• Enhanced Reputation.

Through several phases, the Software Development Life Cycle, or SDLC, encourages secure coding practices:

1. Requirement Analysis,
2. Design Phase,
3. Implementation,
4. Testing,
5. Deployment, and
6. Maintenance.

9. Define vulnerability scanners and their role.

Automated programs called vulnerability scanners are used to find possible security holes and weaknesses in computer systems, networks, and software applications. They are crucial to the framework of preventive security measures since they:

• Inventory and Discovery,
• Vulnerability Detection,
• Prioritization and Risk Assessment,
• Reporting and Remediation, etc.

10. What is penetration testing and its benefits for web application security?

Penetration testing is a technique used to evaluate a computer system’s, network’s, or web application’s security by mimicking actual attacks and looking for holes and flaws. Web application security benefits from penetration testing because:

1. Identification of Vulnerabilities,
2. Real-World Simulation,
3. Risk Prioritization,
4. Compliance Requirements,
5. Improvement of Security Posture,
6. Validation of Security Controls, and
7. Enhanced Customer Trust.

11. Describe secure session management practices.

Secure session management practices include:

• Use of Strong Session IDs,
• Session Expiration,
• Session Revocation,
• Secure Transmission,
• Protection Against Session Fixation,
• Session Data Encryption,
• Client-side storage Security, and
• Monitoring and Logging.

12. Discuss security considerations for API deployments (data protection & access control).

“API security” refers to protecting application programming interfaces (APIs) from unauthorized access and data breaches. Consider the following:

1. Data protection,
2. Access control,
3. Input validation, and
4. Rate limiting, etc.

13. Explain how security is integrated throughout the SDLC.

By integrating security practices like threat modeling, secure coding principles, and security testing into each step of the SDLC, security is integrated throughout, and security considerations are taken care of from requirements gathering to deployment and maintenance.

14. Define continuous security monitoring and its importance.

Continuous security monitoring is the process of continuously keeping an eye out for security risks and vulnerabilities in real-time on an organization’s systems, networks, and applications to quickly identify and address issues. Among the reasons ongoing security monitoring is crucial are:

• Early Threat Detection,
• Reduced Time to Detect and Respond,
• Improved Incident Response Capabilities,
• Enhanced Risk Management, and
• Compliance Requirements.

15. Describe strategies for staying updated on web security threats.

Among the methods for keeping abreast of risks to web security are:

1. Follow Security Blogs and News Websites,
2. Join Security Mailing Lists and forums.
3. Attend Security Conferences and Webinars,
4. Engage with Security Communities, and
5. Monitor Vendor Updates and Security Advisories.

16. What are Web Application Firewalls (WAFs)?

To prevent web-based attacks like SQL injection, cross-site scripting (XSS), and other OWASP Top 10 vulnerabilities, web application firewalls (WAFs) are security solutions that monitor, filter, and block HTTP traffic between a web application and the Internet.

17. Discuss security best practices for cloud-based web applications (data encryption & access control).

The best security practices for cloud-based applications include the following examples:

Data Encryption

• Encrypt data at rest and in transit,
• Use industry-standard encryption algorithms,
• Manage encryption keys securely, etc.

Access Control

• Implement Identity and Access Management (IAM),
• Principle of least privilege,
• Multi-Factor Authentication (MFA),
• Regular access reviews, etc.

Additional Best Practices:

• Secure configurations,
• Regular security assessments,
• Data Loss Prevention (DLP), etc.

18. Identify emerging web security threats and how to address them.

New dangers to web security include:

• API security threats,
• Supply chain attacks,
• Zero-day attacks, etc.

Additionally, I can handle them using the following recommended practices:

API security threats:

• Implement strong authentication and authorization,
• Validate all API input,
• Rate limiting,
• Monitor API activity, etc.

Supply chain attacks:

• Use secure software development practices,
• Maintain software libraries,
• Vet third-party vendors, etc.

Zero-Day Attacks:

• Maintain a strong security posture,
• Patch promptly,
• Deploy Intrusion Detection/Prevention Systems (IDS/IPS), etc.

19. Outline a structured approach for handling a web security incident.

To methodically handle an online security event, the following structured strategy must be used:

1. Preparation,
2. Identification,
3. Containment,
4. Investigation,
5. Remediation,
6. Communication,
7. Documentation, and
8. Post-Incident Analysis.

20. (Scenario) You identify a potential XSS vulnerability. Describe your approach.

Following the discovery of a possible XSS vulnerability, the following actions ought to be performed:

• Immediate Mitigation,
• Analysis and Validation,
• Fix the Vulnerability,
• Update and Patch,
• Test the Fix,
• Review Security Practices,
• Inform Stakeholders,
• Monitor for Exploitation, and
• Document the Incident.

21. (Scenario) Explain your thought process when conducting a security assessment.

The following procedures are what I would do while performing a security assessment:

1. Identify and Enumerate Assets,
2. Review Code,
3. Perform Vulnerability Scanning,
4. Conduct Penetration Testing,
5. Assess Configuration,
6. Analyze Authentication and Authorization,
7. Validate Input and Output Handling,
8. Examine Session Management,
9. Inspect Data Storage and Transmission,
10. Review Logging and Monitoring,
11. Document Findings and Recommendations, and
12. Perform Follow-up Assessments.

22. Discuss the benefits of utilizing OWASP ESAPI for developers.

Developers can profit from using OWASP ESAPI (Enterprise Security API) in several ways.

• Comprehensive Security Controls,
• Consistency,
• Simplicity,
• Maintenance and Updates, and

23. Differentiate between positive and negative input validation techniques.

Negative input validation prohibits known, harmful inputs based on patterns found, while positive input validation only permits known, acceptable inputs based on stringent criteria (whitelisting).

Since positive validation limits inputs to predicted values exclusively, it is generally more secure.

24. How do secure password hashing techniques protect user credentials?

User credentials are safeguarded by secure password hashing algorithms by:

• Irreversibility,
• Salting,
• Slowing Attacks,
• Collision Resistance, and
• Integrity Verification.

25. Explain session hijacking and how session management mitigates it.

To obtain unauthorized access to a user’s session on a web application, an attacker must steal or intercept a valid session token. This is known as session hijacking. Session management prevents the hijacking of sessions by:

1. Secure Token Generation,
2. Encryption,
3. Session Expiration,
4. Regeneration of Session IDs, and
5. Monitoring and Logging.

26. Why are consistent software updates critical?

Regular updates to the software are essential because:

1. Security Patches,
2. Bug Fixes,
3. Performance Enhancements,
4. Compatibility, and
5. Regulatory Compliance.

27. Define the “principle of least privilege” in access control.

To lower the risk of unauthorized access and reduce the damage from security breaches, users should only be provided the minimal degree of access or permissions necessary to do their tasks. This is known as the principle of least privilege.

28. How can business logic flaws be exploited?

Flaws in business logic can be used against you in the following ways:

1. Bypassing Workflow Controls,
2. Abusing Authorization Rules,
3. Manipulating Transactions,
4. Circumventing Validation Checks, and
5. Exploiting Inconsistencies.

29. Define web application security and its core principles.

The technique of securing websites and online services against cyber threats and vulnerabilities is known as web application security. It entails putting safeguards in place to stop harmful activity directed towards web applications, illegal access, and data breaches.

The core principles of Web Application Security include:

1. Confidentiality,
2. Availability,
3. Authentication,
4. Authorization,
5. Non-repudiation, and
6. Accountability.

30. Describe prototype pollution and its security implications.

An attacker can alter the prototype of JavaScript objects that are already included in the language thanks to a flaw in JavaScript called prototype pollution. As a result, this could lead to unintended behavior and allow attackers to get past security measures or steal data.

Mitigations include using secure development practices and ensuring JavaScript libraries are up to date.

Conclusion

Now that you have cleared up your doubts about what kind of questions will be asked in the interview, you should be more confident. These Web Application Security Interview Questions and answers will help you sort out the potential questions an interviewer might ask you. Thus, you can use these Top 30 Web Application Security Interview Questions and answers better. However, suppose you are a beginner in the IT sector who is trying to pursue a career related to Web Application Security. In that case, you should find a reliable source of training and certification to ensure job opportunities for you.

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