The OWASP Top 10 Explained: What Every Business Should Know
The OWASP Top 10 is the most widely recognised list of critical web application security risks. If you run a web application, SaaS platform, or API, these are the vulnerabilities you need to know about.
What Is OWASP?
The Open Worldwide Application Security Project (OWASP) is a non-profit foundation that works to improve software security. Their Top 10 list is updated periodically and represents the most critical security risks to web applications, based on real-world data.
The OWASP Top 10 (2021)
A01: Broken Access Control
What it is: Users can act outside their intended permissions. Viewing other users’ data, modifying records they shouldn’t, or accessing admin functions.
Real example: Changing /api/orders/123 to /api/orders/456 and seeing another customer’s order. This is called an Insecure Direct Object Reference (IDOR).
Why it matters: This is the #1 vulnerability we find in penetration tests. It leads directly to data breaches.
A02: Cryptographic Failures
What it is: Sensitive data exposed due to weak or missing encryption. Passwords stored in plain text, data transmitted without TLS, weak hashing algorithms.
Real example: A database backup stored on a public S3 bucket with customer passwords in plain text.
A03: Injection
What it is: Untrusted data sent to an interpreter as part of a command or query. SQL injection is the most famous, but command injection, LDAP injection, and NoSQL injection all fall here.
Real example: Entering ' OR 1=1 -- into a login form and bypassing authentication entirely.
A04: Insecure Design
What it is: Fundamental design flaws that can’t be fixed by a perfect implementation. Missing threat modelling, insecure business logic.
Real example: A password reset flow that asks security questions with answers that are publicly available on social media.
A05: Security Misconfiguration
What it is: Default configurations, unnecessary features enabled, missing security headers, verbose error messages.
Real example: A production server with directory listing enabled, exposing backup files containing database credentials.
A06: Vulnerable and Outdated Components
What it is: Using libraries, frameworks, or components with known vulnerabilities.
Real example: Running an unpatched version of Apache Struts — the same vulnerability that led to the Equifax breach.
A07: Identification and Authentication Failures
What it is: Weaknesses in authentication mechanisms. Weak passwords allowed, missing brute-force protection, session tokens that don’t expire.
Real example: No rate limiting on the login endpoint, allowing an attacker to try thousands of passwords per minute.
A08: Software and Data Integrity Failures
What it is: Code and infrastructure that doesn’t verify integrity. Insecure CI/CD pipelines, auto-updates without verification.
Real example: A compromised npm package injecting malicious code into your build pipeline.
A09: Security Logging and Monitoring Failures
What it is: Insufficient logging, monitoring, and alerting. If you can’t detect an attack, you can’t respond to it.
Real example: An attacker exfiltrating data over weeks with no alerts triggered because failed login attempts weren’t logged.
A10: Server-Side Request Forgery (SSRF)
What it is: An application fetches a remote resource based on user input without validation. Attackers use this to access internal services.
Real example: A URL preview feature that can be tricked into fetching http://169.254.169.254/latest/meta-data/ to steal AWS credentials.
What Should You Do?
- Get tested. A penetration test aligned to the OWASP Top 10 will tell you exactly where you stand.
- Prioritise fixes. Not all vulnerabilities are equal. Focus on the ones with the highest business impact.
- Build securely. Train your developers on secure coding practices. Prevention is cheaper than remediation.
How We Can Help
At XASPRO, every penetration test includes full OWASP Top 10 coverage. We test for all ten categories, report findings with business impact context, and provide code-level remediation guidance.