What is OWASP?
If you work in web application security, you've almost certainly heard of OWASP. But what exactly is it, and why has it become the global standard for understanding application security risks?
OWASP—the Open Worldwide Application Security Project—is a nonprofit foundation dedicated to improving software security. Founded by Mark Curphey on September 9, 2001, OWASP started as a simple mailing list and collection of documents. Today, it has grown into one of the most influential organizations in cybersecurity, with over 32,000 members, 8,500 contributors, and more than 300 active projects.
What makes OWASP unique is its commitment to being completely open: all projects, tools, documents, forums, and chapters are free and accessible to anyone interested in application security. This openness has led to widespread adoption—the OWASP Top 10 is referenced by major standards including PCI DSS, DISA-STIG, and the U.S. Federal Trade Commission.
Why OWASP Matters
The numbers tell the story of why application security—and OWASP's guidance—is critical:
In early 2023, OWASP's Board voted to change the 'W' from 'Web' to 'Worldwide' to reflect the organization's expansion beyond just web applications. OWASP now covers IoT, system software, APIs, and more.
OWASP Top 10: Web Application Security Risks
The OWASP Top 10 is the most recognized document in application security. First published in 2003, it represents a broad consensus about the most critical security risks facing web applications. The list is updated every few years based on data from security organizations worldwide.
The current version, released in September 2021, reflects significant changes in the threat landscape. Three new categories were added, and Broken Access Control moved from #5 to the top spot—a reflection of how access control failures have become the dominant security issue.
The 2021 Top 10 List
Here are the ten most critical web application security risks according to OWASP:
A01 - Broken Access Control
The #1 risk. 94% of applications tested had broken access control. Occurs when users can act outside their intended permissions.
A02 - Cryptographic Failures
Formerly 'Sensitive Data Exposure'. Failures related to cryptography leading to exposure of sensitive data.
A03 - Injection
SQL, NoSQL, OS, and LDAP injection. Untrusted data sent to an interpreter as part of a command or query.
A04 - Insecure Design
NEW in 2021. Focuses on design and architectural flaws. Calls for threat modeling and secure design patterns.
A05 - Security Misconfiguration
Missing security hardening, unnecessary features enabled, default accounts unchanged, overly verbose error messages.
A06 - Vulnerable Components
Using libraries, frameworks, or modules with known vulnerabilities. Includes both direct and transitive dependencies.
A07 - Authentication Failures
Formerly 'Broken Authentication'. Session management weaknesses allowing attackers to compromise passwords or tokens.
A08 - Software Integrity Failures
NEW in 2021. Relates to code and infrastructure without integrity verification—CI/CD pipelines, auto-updates.
A09 - Logging & Monitoring Failures
NEW in 2021. Insufficient logging, detection, monitoring, and active response. Average breach detection: 277 days.
A10 - Server-Side Request Forgery
SSRF flaws occur when a web app fetches a remote resource without validating the user-supplied URL.
OWASP API Security Top 10
As APIs have become the backbone of modern applications, OWASP created a separate project focused specifically on API security risks. The API Security Top 10 2023 addresses vulnerabilities unique to API design and implementation.
APIs present different security challenges than traditional web applications. They're designed for machine-to-machine communication, often expose more functionality, and have become prime targets for attackers—roughly 1 in 6 attacks now target APIs.
API Security Top 10 (2023)
| # | Vulnerability | Key Risk |
|---|---|---|
| API1 | Broken Object Level Authorization (BOLA) | 40% of API attacks exploit BOLA—unauthorized access to data by manipulating object IDs |
| API2 | Broken Authentication | Stolen tokens, credential stuffing, brute-force attacks on API endpoints |
| API3 | Broken Object Property Level Authorization | Excessive data exposure or mass assignment vulnerabilities |
| API4 | Unrestricted Resource Consumption | No rate limiting leads to DoS, economic damage, or resource exhaustion |
| API5 | Broken Function Level Authorization (BFLA) | Unauthorized users executing administrative API functions |
| API6 | Unrestricted Access to Sensitive Business Flows | Automated abuse of business logic (ticket scalping, spam) |
| API7 | Server-Side Request Forgery (SSRF) | APIs fetching resources without validating user-supplied URIs |
| API8 | Security Misconfiguration | Missing patches, unnecessary features, improper permissions |
| API9 | Improper Inventory Management | Shadow APIs, outdated versions still accessible |
| API10 | Unsafe Consumption of APIs | Trusting third-party API data without validation |
Broken Object Level Authorization (BOLA) is involved in approximately 40% of all API attacks. It occurs when an API endpoint doesn't properly verify that the user making a request has permission to access the specific resource. Attackers simply change object IDs in requests to access unauthorized data.
How WAF Protects Against OWASP Threats
A Web Application Firewall (WAF) is one of the most effective tools for defending against OWASP Top 10 vulnerabilities. By inspecting HTTP/HTTPS traffic in real-time, WAFs can detect and block attacks before they reach your applications.
According to recent data, virtual patches through WAF blocked 62% of web attacks and 71% of API attacks in 2024. This makes WAF an essential layer in any defense-in-depth security strategy.
WAF Protection by OWASP Category
| OWASP Risk | WAF Capability | Protection Method |
|---|---|---|
| Injection (A03) | SQL/XSS/Command Injection Rules | Pattern matching, input validation, encoding detection |
| Broken Access Control (A01) | Access Policy Enforcement | IP reputation, geo-blocking, authentication integration |
| Security Misconfiguration (A05) | Virtual Patching | Immediate protection for unpatched vulnerabilities |
| SSRF (A10) | Request Validation | URL allowlisting, internal network protection |
| Cryptographic Failures (A02) | SSL/TLS Enforcement | Certificate validation, cipher suite control |
| BOLA/BFLA (API1/API5) | API Security Rules | Schema validation, authorization checks, rate limiting |
Implementing OWASP Security
Protecting your applications against OWASP vulnerabilities requires a multi-layered approach:
Adopt a WAF with OWASP Rule Sets
Deploy a WAF with pre-built OWASP Core Rule Set (CRS) protection. This provides immediate coverage for common attack patterns and can be customized for your specific applications.
Implement Secure Development Practices
Train developers on OWASP risks and integrate security testing into your CI/CD pipeline. Use tools like OWASP ZAP for automated security scanning during development.
Maintain Component Inventory
Keep track of all libraries, frameworks, and dependencies. Subscribe to security advisories and patch vulnerabilities promptly—over 90% of breaches exploit known, unpatched vulnerabilities.
Enable Comprehensive Logging
Log security-relevant events and monitor for anomalies. The average 277-day breach detection time can be dramatically reduced with proper logging and SIEM integration.
Protect Your APIs Specifically
APIs need dedicated security controls including rate limiting, schema validation, and proper authorization at every endpoint. Don't rely solely on traditional WAF rules designed for web applications.
Frequently Asked Questions
OWASP itself is not a compliance standard, but its guidelines are referenced by many standards including PCI DSS, DISA-STIG, and various regulatory frameworks. Many organizations use OWASP Top 10 compliance as a baseline security requirement.
The OWASP Top 10 is typically updated every 3-4 years. The current version is from 2021, and OWASP is currently developing a 2025 release candidate. Updates are based on vulnerability data contributed by security organizations worldwide.
The OWASP Top 10 focuses on traditional web application vulnerabilities, while the API Security Top 10 addresses risks specific to APIs. APIs have unique concerns like BOLA, improper inventory management, and business logic abuse that aren't covered in the main Top 10.
A WAF provides strong protection against many OWASP vulnerabilities, particularly injection attacks, but it's not a complete solution. Issues like insecure design (A04) and software integrity failures (A08) require secure development practices. WAF should be part of a defense-in-depth strategy.
Visit owasp.org for free access to all OWASP resources. Key projects include the Top 10, API Security Top 10, Application Security Verification Standard (ASVS), and security testing tools like OWASP ZAP. OWASP also has local chapters worldwide.
OWASP-Ready Protection
TR7's WAF provides comprehensive protection against OWASP Top 10 and API Security Top 10 vulnerabilities with pre-configured rule sets, real-time threat detection, and virtual patching capabilities.
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