Securing Web Applications: The Importance of OWASP Top 10 in Pentesting

TL;DR 

Since web applications are essential to businesses, they face the ever-growing risk of cyber threats. The OWASP Top 10 is a global, community-driven list of critical vulnerabilities that penetration testers can use to structure comprehensive security assessments. By understanding and addressing these common risks, from injection flaws to broken authentication, you can proactively identify weaknesses before attackers exploit them. Combining secure coding practices, regular penetration testing, and OWASP-guided assessments significantly strengthens your security posture and reduces exposure to real-world threats. 

Intro to Web Application Security 

Though web applications are central to how businesses operate and deliver services, they also present a growing attack surface for cyber threats. Common threats are frequently exploited because of overlooked coding mistakes or misconfigured systems. Effective penetration testing can help protect applications from being exploited. By mimicking the tactics of malicious attackers, pentesters find hidden weaknesses before bad actors do. Here is what your team can do to better understand and mitigate these risks. 

What is the OWASP Top 10? 

A key resource guiding both development and testing efforts is the Open Worldwide Application Security Project’s (OWASP) Top 10, a curated list of the most common and severe web application risks. Essentially, OWASP shares and explains global research, industry data, and expert analysis through practical and identifiable vulnerability categories. Over time, the OWASP Top 10 has gained a reputation for shaping security policies, development frameworks, and compliance standards. As a result, it’s now known as a core source of information for the industry. By using the OWASP Top 10, pentesters are able to focus on high-impact vulnerabilities that are likely to occur, which assists with efficiency and comprehensive testing. 

Breaking Down the OWASP Top 10 Vulnerabilities 

Each of the following vulnerabilities shows a significant category of risk that attackers exploit in real-world scenarios. 

1. Injection Attacks (SQL Injection, NoSQL Injection, Command Injection) 

Injection attacks occur when untrusted input is interpreted as code or commands by the system, allowing attackers to alter the intended behavior of a query or process. Basically, attackers can trick systems into executing unintended commands, leading to data theft, corruption, or full system compromise. 

Some methods to prevent injection attacks would be through the use of parameterized queries and prepared statements, by sanitizing and validating all user inputs, or employing Object-Relational Mapping (ORM) frameworks that abstract low-level database queries.

2. Broken Authentication

Flaws in authentication allow attackers to compromise passwords, session tokens, or exploit flaws in logic to assume another user’s identity. This vulnerability can materialize as credential stuffing with known username-password pairs, or even session fixation or hijacking attacks due to insecure session management. 

To best avoid this issue, implement multi-factor authentication (MFA), use secure password storage with hashing algorithms like bcrypt, rotate session IDs after login, and enforce session expiration. 

3. Sensitive Data Exposure 

If not protected properly, sensitive data, such as personally identifiable information (PII), financial details, and credentials, can be exposed, leading to identity theft, fraud, or regulatory penalties. Encrypt sensitive data at rest and in transit using strong algorithms, avoid storing sensitive data unless absolutely necessary, disable caching for sensitive pages, and avoid exposing data in URLs.  

4. XML External Entities (XXE) Attacks

Attackers can exploit XXE vulnerabilities to read local files, perform SSRF (Server-Side Request Forgery), or even execute remote code. To mitigate this risk, disable Document Type Definition (DTD) processing in XML parsers, use secure libraries that prevent external entity resolution by default, and opt for JSON over XML when possible. 

5. Broken Access Control 

When access control is misconfigured or missing, it is possible for users to act outside of their intended permissions in viewing or modifying data they shouldn’t access. To avoid this risk, enforce access controls on the server side, use role-based access controls (RBAC) consistently, and never rely solely on client-side enforcement. 

6. Security Misconfiguration 

Applications or servers often run with insecure default settings, exposed error messages, or unnecessary features enabled, which opens them up to attacks. Protect applications and infrastructure by hardening server and application configurations, use automated tools to detect misconfigurations, and regularly review and update security settings. 

7. Cross-Site Scripting (XSS)

When untrusted scripts are executed in users’ browsers, attackers can steal cookies, deface content, or redirect users to malicious sites. To prevent XSS, we recommend sanitizing and escaping user input on output, using Content Security Policy (CSP) headers, and choosing frameworks with built-in XSS protection. 

8. Insecure Deserialization 

Insecure deserialization allows attackers to tamper with serialized objects, potentially leading to remote code execution or privilege escalation. Avoid deserializing objects from untrusted sources, implement integrity checks (e.g., digital signatures), use simple data formats like JSON, and enforce strict input validation to avoid this issue. 

9. Using Components with Known Vulnerabilities 

Outdated or vulnerable libraries and frameworks are a common attack vector, and exploiting known issues requires minimal effort when applications fail to update their dependencies. Here are a few ways to fix this: Monitor dependencies with tools like OWASP Dependency-Check, Snyk, or npm audit, apply patches and updates promptly, and remove unused components. 

10. Insufficient Logging and Monitoring 

Without proper logging and monitoring, breaches can go undetected for weeks or even months. The lack of logging and monitoring increases damage and makes incident response more difficult. Begin logging critical events like authentication failures, access control violations, and input validation errors, in addition to setting up alerts for suspicious activity and regularly reviewing logs. 

The Role of OWASP Top 10 in Penetration Testing 

As an industry benchmark for penetration testers, the OWASP Top 10 guides assessments toward the most critical and commonly exploited web application vulnerabilities, ensuring coverage of high-risk areas. Breaches happen frequently from exploited OWASP-listed vulnerabilities, validating  the standard awareness document’s relevance and practicality. Your organization can stay ahead of evolving threats and ensure vulnerabilities are identified and remediated before they’re exploited by rooting your security assessments and pentesting practices in OWASP principles. 

Best Practices for Securing Web Applications 

Securing web applications requires a proactive approach that starts with implementing secure coding practices like input validation, output encoding, proper authentication, authorization controls, and error handling. Conducting regular security audits and penetration tests are also important as they help uncover security concerns, misconfigurations, and logic issues that automated tools might miss.  

By combining secure coding, continuous testing, and automation, your organization can significantly reduce your exposure to common threats. Security should be a core element of application design from the start. Ensure this happens by embedding these best practices into the software development lifecycle as soon as possible. 

Take the Next Step in Strengthening Your Security 

It’s time to take action in securing your web applications, and NetSPI can help. Need expert penetration testing services? Contact us today to strengthen your web application security and testing.