In the present era, where hackers with specialized skills shuttle through the site in search of such vulnerabilities to exploit them to earn money, the demand for applying proactive web application security professionals has never been higher. These specialists make up the core team which identifies and removes any dangers from web pages to ensure that confidential data don’t get sold on illegal markets. Such hacking incidents can only be stopped if we have more security experts in web application security.

This in-depth article will assist you in exploring the 30 best interview questions with corresponding answers on web application security. This guide is especially intended for the web app protection job candidates to master their interview skills and to get the insights into the key issues which can be of great interest for the hiring managers. Dive in and bring your chosen knowledge from this session to the next interview for you to contribute to the development of a safer digital world.

1. What is the role of encryption in security?

Encryption is one of the basic techniques for encoding plain texts from data before transmission using cryptographic algorithms. This messy data will be incomprehensible without a corresponding decryption key, as it only allows messages to be decoded with a correct key. Thus, encryption excludes unauthorised access and prevents confidentiality issues. Encryption stands between data communication and storage and thus prevents unlawful access or modification by antagonists.

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2. Why should a cyber threat be recognized as a ‘Vulnerability’?

Vulnerability can be defined as any system deficiency that makes the system vulnerable to the exploitation of external attackers and software bugs. In the absence of complete security testing, systems are more likely to have vulnerabilities. Periodic patches and fix applications are important to deal with vulnerabilities, improve resilience, and guarantee the system against various threats.

3. Can you explain what “Penetration Testing” is?

Penetration testing, usually shortened to “pen testing,” is a cybersecurity attack on a computer network or application to note vulnerabilities and possible options to fix them. In the tester’s capacity, they duplicate the enemy’s actions by discovering the system’s weaknesses to identify its robustness. It’s with the purpose that we can discover the backdoors before malicious actors come, which will be followed by proactive defense mechanisms.

4. Can you explain security testing and how it works?

Security testing involves executing particular tests to identify the security vulnerabilities of information system processes. The tester conducts simulations in which they play the role of the attacker to identify system weaknesses. A primary goal of security testing is to disclose the vulnerabilities of applications or systems and strengthen their defense against unauthorized access or data breaches.

5. Please provide additional information on Cross-Site Scripting (XXS)

Cross-site scripting, or XSS, is an example of client-side code injection in which attackers inject malicious scripts into web users’ browsers. This vulnerability penetrates session tokens, cookies, and other confidential data. XXS manifests in three main forms: reflected, stored, and DOM.

One-way XXS involves injecting malicious code into the script coming from the HTTPS requests, whereas, in the case of stored XXS, the scripts are saved in the database. DOM XXS/D, or Document Object Model XXS, targets client-side rather than server code.

6. Tell me about some benefits that OWASP provides

Some key benefits that OWASP offers to businesses and IT professionals include:

• Enhancing application support against digital threats.
• The decrease in the number of errors and system failures.
• Facilitating stronger encryption methods.
• Higher the rate of application approval.
• Improvement of the company’s image as a software company.

7. Can you tell me about OWASP Top 10 vulnerabilities?

Yes, I can tell you about the OWASP Top 10 vulnerabilities. They include

• Broken Authentication and Session Management
•  Cross-site scripting
• Insecure direct object reference
• Failure to restrict
• Insecure cryptographic storage
• The fact that parents could restrict URL access does not happen.
• Malicious file execution
• Instances of information leakage and wrong way of dealing with the errors.
• Injection
• Insecure communications

8.     Is it possible to distinguish between authentication and authorization in the case of web applications? Could you please define it?

This looks like one of the important Web application security interview questions. The concepts of authorization and authentication in web applications are fairly common and usually used interchangeably. However, these terms are two concepts that have separate goals, although they’re similar.

Authentication is the process of verifying a user’s, website’s, or entity’s identity, ensuring they are who they claim to be, like entering a password for an online account. It checks the right to access a system.

Authorization, on the other hand, involves granting or denying access rights to resources or functions after authentication. It determines if a user has the necessary privileges to perform specific actions or view certain files. A reliable system must include both authentication and authorization.

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9. Can you list common security vulnerabilities in web apps?

Sure, here is a list of Common security vulnerabilities in web apps

• Cross-Site Scripting (XSS)
• SQL Injection
• Cross-Site Request Forgery (CSRF)
• Insecure Direct Object References (IDOR)
• Sensitive Data Exposure
• Security Misconfigurations
• Broken Authentication
• Insecure Deserialization
• Unvalidated Redirects and Forwards

10.  What are some essential best practices for ensuring the security of web applications?

Application security is a critical pillar of the cyber security system that can effectively address the evolving cyber threats. Some of the application security best practices are:

• Secure Coding Standards
• Least Privilege Principle
• Regular Security Updates
• Strong Authentication Mechanism
• Encryption of Sensitive Data
• Security testing and auditing
• Secure Configuration Management
• Access Management and Session Tracking
• Incident Response Planning

11.  What are the core secure coding principles for web apps?

Sure! Here they are:

i. Input Validation: Inspect and filter the input data to protect against registered XSS and SQL injection.

ii. Output Encoding: The intermediate process of encoding output data will help to prevent cross-site scripting vulnerabilities.

iii. Authentication and Authorization: Introduce strict authentication procedures and place the right authorization controls.

iv. Error Handling: Provide informative error messages efficiently but in a way that does not divulge any personal data.

v. Session Management: Securing sessions with secure cookies as well as token-based authentication.

vi. Secure Configuration: Proper configuration of the servers and frameworks; this avoids the appearance of vulnerabilities by software updates.

vii. Data Encryption: Data storing and transit, encrypting sensitive files and contents.

viii. Secure File Uploads: Make sure of the collaboration of safe file uploading to avoid wrongful execution.

12.  Would you please tell me about some quite strong methods to protect me from XSS attacks on websites?

 Here are some effective Cross-site scripting (XSS) prevention techniques:

1. Input Validation: Validate and sanitize any user-supplied data if you will process their information online or display it on web pages. This prevents abusers from injecting malicious scripts by using input fields.​
2. Output Encoding: Set up user input encoding and dynamic content compilation before accessing them from a browser. To prove that any potentially harmful traits are converted into HTML entity characters – thus being visible safely without executing scripts.
3. Content Security Policy (CSP): Set CSP (Content Security Policy) headers that allow content loading and execution only from allowed sources like website scripts. This permits, to a certain extent, the occurrence of XSS attacks to be restricted by excluding the possibility of executing unauthorised scripts.
4. HTTPOnly and Secure Flags for Cookies: Use the HTTPOnly flag on cookies to prevent client-side scripts from accessing them, minimising XSS session hijacking. The secure flag must also be used to send the cookies over secure HTTPS only.
5. Regular Security Updates: Advanced security techniques, such as having the latest versions of web application frameworks, libraries, and dependencies to fix XSS flaws, are necessary. Check for security alerts and fixes to reduce the chances of hackers exploiting your system.

13.  I’ve heard about SQL injection attacks being a significant threat to web applications. Could you explain some effective methods for preventing SQL injection?

SQL injection is a critical vulnerability that attackers exploit to manipulate databases by injecting malicious SQL queries. Here are some prevention methods:

• Parameterized Queries: Use placeholders for user input instead of concatenation to prevent altering the query structure.
• Input Validation: Validate user input to ensure it meets required formats and lacks suspect characters.
• Stored Procedures: Store SQL logic within the database to reduce exposure to injection attacks.
• Object-Relational Mapping (ORM): Use ORM frameworks to automatically generate and parameterize SQL statements, minimizing injection risks.
• Least Privilege Principle: Limit database user permissions to necessary actions to contain the impact of injections.
• Web Application Firewalls (WAFs): Install WAFs to monitor and block malicious SQL injection attempts by filtering abnormal HTTP requests.

14.  What is Intrusion Detection?

The intrusion detection process implies identifying the cancers underway and then acting on them. It iterates with information from various sources and systems, interprets that data, and highlights the probable attack paths.

Intrusion Detection checks for:

• Potential attacks
• Abnormal activities
• System data auditing

15.  What is “SQL Injection”?

SQL Injection is the most common vulnerability and one of an attacker’s favorite tools for retrieving privileged information. A hacker has a keen sense of exploitation and consequently will take advantage of vulnerabilities in a system by executing SQL queries, finding a means to bypass security, and retrieving critical information. An SQL injection can also be a source of threats for data theft or system crashes.

Thus, full security testing is a must. Right measures such as input field checking and special character care are unavoidable.

16.  What does security testing mean, and what are its attributes?

The Security Testing can be classified by all the significant characteristics that it has:

• Authentication
• Authorization
• Integrity
• Non-repudiation
• Confidentiality
• Availability
• Resilience

17.  Why is HTTPS and SSL/TLS implementation crucial for the security of web applications?

Some reasons that make HTTPS and SSL/TLS implementation important are:

1. Data Encryption: HTTPS encrypts data for confidentiality.
2. Data Integrity: SSL/TLS ensures data remains unchanged.
3. Trust Establishment: Certificates authenticate servers.
4. Protection Against Phishing: HTTPS reassures users.
5. Compliance Requirements: HTTPS meets regulatory standards.

18.  How do security testing methodologies ensure the resilience of web applications against cyber threats?

Security testing methodologies for web applications:

1. Black-Box Testing: Simulates real attacks.
2. White-Box Testing: Analyses internal code.
3. Grey Box Testing: Done with Partial information.
4. Penetration Testing: Explores vulnerabilities.
5. Code Review: Checks for errors.
6. Vulnerability Scanning: Identifies weaknesses.
7. Fuzz Testing: Tests input validation.
8. Threat Modelling: Assesses potential risks.

19.  Can you give me insight into the definition of Business Logic, which specifically applies to web applications? How is testing for Business Logic security vulnerabilities different from the traditional XSS or SQL injection tradition?

Business logic in a web app refers to the code replicating real-world business operations and decisions. Testing for business logic weaknesses differs from traditional vulnerability testing like XSS or SQL injection. Instead of just technical errors, it involves scrutinising developers’ assumptions about user interactions. Unlike traditional scanners, detecting business logic flaws requires a deep understanding of the application’s goals and behaviour.

20.  What guidelines would you provide a customer when attempting to fix this DOM-based Cross-Site Scripting (XSS) vulnerability issue?

It’s recommended to avoid passing user-supplied inputs in HTML attributes, as these can affect the execution of JavaScript functions and can be exploited. Active checks are necessary to validate the inputs, only allow access for those that contain expected characters, and avoid searching for and cleaning malicious characters. Furthermore, learning how to code can add another barrier to the XSS implantation attack.

21.  What are the fundamental principles of application security?

The fundamental principles of application security include:

• Least Privilege: Give users access at a minimum level.
• Defence in Depth: Apply security in different dimensions.
• Fail Securely: Having systems default in secure states is essential.

22.  How do you ensure secure coding in web applications?

To ensure secure coding in web applications, it’s essential to:

• Input Validation: Authenticate and cleanse user input.
• Output Encoding: Canvass output data against XSS.
• Proper Error Handling: Display Informative error message.

23.  Why is it crucial to keep software and libraries up to date?

It is crucial to keep software and libraries up to date because:

• Patch Management: Fix the known deficiencies without delay.
• Vulnerability Mitigation: Lessen the chances of abuse.
• Compliance Requirements: Comply with data protection norms and rules.

24.  What are the full names of abbreviations associated with Software security?

 Abbreviations related to software security include:

• ISDN – Integrated Services Digital Network.
• DDS – Digital Data System.
• SSH – The Secure Shell.
• IPsec – Internet Protocol Security, a suite of protocols for securing the Internet.
• CHAP – Challenge Handshake Authentication Protocol.
• BONDING – Bandwidth On Demand Interoperability Group.
• USM – User-based Security Model.

25.  What is ISO 17799?

ISO/IEC 17799, an originally British standard, specifies the best practices for Information Security Management based on an organization’s readiness and the intensity of electronic information assets. It is the norm for information security in organizations of any size.

26.  What are some of the things that trigger vulnerabilities?

Factors leading to vulnerabilities include:

• Design flaws: The existing lack of control and easy passages hackers use to safely reach systems.
• Passwords: Hackers sneak in when they get the customer’s passwords. Following carefully thought-out password regulations significantly reduces these security threats.
• Complexity: Extended software creates a chance of vulnerabilities.
• Human Error: Hackers usually exploit lapses in security standards influenced by human errors.
• Management: Weak data management can only be judged to source dangerous system operations.

27.  What elements play a defining role in creating an SSL session connection?

The elements are:

•  Server and client random
•  Server writes MAC secret
•  Client writes MAC secret
•  Server write key
•  Client write key
•  Initialization vectors
•  Sequence numbers

28.  Define file enumeration.

File enumeration stands for deliberate browsing and slow URL manipulations. Unlike in standard browsing, hackers treat the URL as an ordinary callable function with redefined parameters to access concealed data such as archived files, early versions, or data under development.

29.  What will be the benefits provided by an intrusion detection system?

The benefits are:

• Network Intrusion Detection (NIDS)
• Network Node Intrusion Detection System (NNIDS)
• Host Intrusion Detection System (HIDS).

30.  Explain HIDS

Hosting Intrusion Detection System (HIDS) is a computer security technology that generates a picture of the current system and compares it with the previous ones. If the critical file is being changed or erased, the HIDS system generates an alert and informs the administrator.