The OWASP Top 10 is a highly respected guide listing the ten most critical security risks in web applications, published by the Open Web Application Security Project (OWASP). It’s designed to help developers and organizations recognize, prioritize, and fix vulnerabilities before they become serious threats.
Below is a clearer, more detailed breakdown of each OWASP Top 10 category:
- Simple definition (one sentence)
- Why it matters (brief explanation)
- Three real-world examples (bulleted list with links to sources)
1. Broken Access Control
Simple definition: When someone accesses or manipulates parts of an application that they shouldn’t.
Why it matters:
Access control ensures that users only have permissions suitable for their role. If it fails—through URL manipulation, missing API checks, or weak authorization—attackers can bypass limitations to view or change sensitive data or functionality.
Real-world examples:
- In 2021, ~533 million Facebook profiles were scraped due to missing server-side access control on an API, exposing details like phone numbers and names. Read more
- A 2014 Snapchat API oversight allowed hackers to grab 4.6 million usernames and phone numbers through brute-force enumeration. Read more
- In a test case, navigating directly to hidden URLs (“forced browsing”) grants non-paying users access to content meant only for subscribers—another form of access control failure. See example
2. Cryptographic Failures
Simple definition: When sensitive data isn’t properly encrypted or is protected with weak methods, making it easy to exploit.
Why it matters:
Cryptography is the security backbone for sensitive data—both stored and in transit. Weak or absent encryption makes it trivial for attackers to steal, read, or tamper with data.
Real-world examples:
- The 2012 LinkedIn breach exposed 117 million passwords secured with weak SHA‑1 hashing and no salt. More details
- Many websites still rely on HTTP instead of HTTPS, putting user sessions at risk from eavesdropping—an ongoing industry issue (common practice).
- Legacy systems frequently use outdated hashing algorithms such as MD5 or SHA‑1, both known to be insecure.
3. Injection
Simple definition: Malicious input tricks the system into running unwanted commands or queries.
Why it matters:
Injection flaws—like SQL injection—happen when unfiltered user input enters an interpreter (a database, script, etc.). Attackers can manipulate queries or commands to access, modify, or delete data.
Real-world examples:
- The 2017 Equifax breach stemmed from an unpatched Apache Struts vulnerability allowing command execution via crafted headers. Read more
- Gab’s 2021 breach exposed 70 GB of user data through SQL injection. Read more
- The MOVEit file-transfer software suffered a SQL injection attack in 2023, affecting major organizations like the BBC and British Airways. Read more
4. Insecure Design
Simple definition: The system was built without considering potential security holes from the start.
Why it matters:
Security isn’t just about clean code—it starts in design. If developers skip planning for things like rate limiting, proper authentication flows, or safe defaults, the system will have vulnerabilities baked in.
Real-world examples:
- Password reset tokens that never expire or lack multi-factor checks can be exploited to take over accounts.
- Systems without rate limits allow brute-force attacks against login pages.
- Financial systems missing transaction validation may allow unauthorized or excessive transfers.
5. Security Misconfiguration
Simple definition: Poor default settings or leaking sensitive system details expose you to attacks.
Why it matters:
Mistakes like default credentials, exposed debug messages, or broad permission settings expose apps to easily avoidable attacks.
Real-world examples:
- Management consoles left with “admin/admin” default login credentials.
- Error pages showing directory paths or system versions.
- Internal tools (like Jira) exposed publicly—similar to a well-known JIRA leak—but note: the Kardashian app API leak highlights similar insecure APIs. Read more
6. Vulnerable and Outdated Components
Simple definition: Relying on old or compromised code opens vulnerabilities known to hackers.
Why it matters:
Applications often use libraries or plugins that may contain known flaws. Attackers exploit these if organizations don’t update or patch them promptly.
Real-world examples:
- The Log4Shell exploit (Log4j) affected systems worldwide due to unpatched vulnerable code.
- Public package repositories (npm, PyPI) have been targeted by attackers inserting malicious code.
- High-profile outages or breaches occur when one widely used vulnerable component is exploited.
7. Identification and Authentication Failures
Simple definition: Weak login or identity checks that let attackers assume someone else’s identity or hijack accounts.
Why it matters:
If authentication is weak—poor passwords, no MFA, flawed sessions—attackers can impersonate users or maintain unauthorized access.
Real-world examples:
- Allowing trivial passwords like “123456” without enforcing MFA.
- Session IDs that stay valid after logout or across sessions lead to hijacking.
- No lockouts or defense against repeated failed logins enable brute-force or credential stuffing.
8. Software and Data Integrity Failures
Simple definition: The system trusts updates, packages, or pipelines without verifying they’re genuine.
Why it matters:
Unchecked system updates or CI/CD workflows can be hijacked to inject malware or stolen code into production without notice.
Real-world examples:
- Fake software updates distributed by attackers to deliver malware.
- Dependency confusion attacks where malicious public packages spoof internal ones.
- CI/CD pipelines ignoring tampering allow unauthorized code changes en route to deployment.
9. Security Logging and Monitoring Failures
Simple definition: No logs or alerts means breaches go unnoticed until it’s too late.
Why it matters:
Without proper logging, notification, and monitoring, attackers can operate undetected—stealing data or escalating access without being caught.
Real-world examples:
- Admin actions or login attempts that are never logged.
- Disorganized logs across systems leave gaps attackers exploit.
- Alerts routed to unchecked inboxes mean compromise remains hidden.
10. Server‑Side Request Forgery (SSRF)
Simple definition: Attackers trick your app into making unseen requests—sometimes to internal systems.
Why it matters:
If your app fetches external URLs without checks, attackers can direct it to internal services (e.g., cloud metadata) and gain secret credentials or internal access.
Real-world examples:
- The Capital One breach (2019) involved SSRF to access AWS metadata and steal over 100 million records. Read more
- A Minecraft server SSRF flaw in 2018 allowed arbitrary code execution and further attacks. Read more
- The StayHub case where an app’s feature triggered SSRF to internal systems. Read more
Final Thoughts
The OWASP Top 10 isn’t just a list—it’s a vital security reference to help you build safer web apps. By understanding these risks in simple terms and seeing real-world examples with links, your team can better guard against threats.
Additional sources
- Facebook scraping 533M profiles: https://www.bleepingcomputer.com/news/security/facebook-attributes-533-million-users-data-leak-to-scraping-not-hacking/
- Snapchat API leak (4.6M users): https://www.forbes.com/sites/anthonykosner/2014/01/01/4-6-million-snapchat-usernames-and-phone-numbers-captured-by-api-exploit/
- Forced browsing example: https://www.synack.com/exploits-explained/preventing-broken-access-control-the-no-1-vulnerability-in-the-owasp-top-10-2021/
- LinkedIn SHA‑1 breach: https://medium.com/%40nimabargestan/real-world-breaches-mapped-to-owasp-top-10-fcda69bcbe94
- SQL injection examples (Gab, MOVEit): https://en.wikipedia.org/wiki/SQL_injection
- Kardashian app insecure API: https://www.wired.com/2015/09/common-api-problem-behind-the-kardashian-jenner-sites-user-information-leak
- Capital One SSRF breach: https://learn.snyk.io/lesson/ssrf-server-side-request-forgery/
- Minecraft SSRF example: https://www.securityjourney.com/post/owasp-top-10-server-side-request-forgery-explained
- StayHub SSRF example: https://medium.com/%40natarajanck2/understanding-server-side-request-forgery-ssrf-with-a-simple-real-life-example-a14650bd5317
