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🌍 The World of OWASP and the OWASP Top Ten

A complete introductory tutorial

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1. What is OWASP?

OWASP stands for Open Worldwide Application Security Project.
It’s a non-profit foundation whose goal is to improve the security of software worldwide.

Key characteristics:

• Vendor-neutral – not owned by any company; no commercial lock-in.
• Community-driven – thousands of volunteers globally.
• Open – projects, standards, tools, and documentation are free.
• Global – local chapters, regional conferences, global AppSec events.

OWASP produces:

• Standards & frameworks – OWASP Top 10, ASVS, MASVS, SAMM, WSTG.
• Developer guidance – Proactive Controls, Cheat Sheet Series.
• Tools – OWASP ZAP, Dependency-Check, AMASS, etc.
• Training resources – OWASP Juice Shop, Security Shepherd, talks, and docs.

Mission (paraphrased):

Make application security visible and understandable, so individuals and organizations can make informed decisions.

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2. Why OWASP?

Why do security, dev, and audit teams keep talking about OWASP?

2.1 Solves a universal problem

• Software is everywhere: web, mobile, cloud, APIs, microservices, IoT.
• Most organizations repeat the same security mistakes.
• OWASP gives a common language (e.g., “Broken Access Control”) and shared playbook for fixing those mistakes.

2.2 De-facto industry standard

• Security programs and audits often reference OWASP Top Ten and ASVS.
• PCI DSS, many RFPs, and vendor security questionnaires ask whether you address OWASP Top 10 risks. (sucuri.net)
• Consulting firms and cloud providers base their guidance on OWASP categories.

2.3 Covers the entire lifecycle

OWASP is not only “vulnerability lists.” It covers:

• Requirements & design – ASVS, MASVS.
• Implementation – Proactive Controls, Cheat Sheets.
• Testing – WSTG.
• Operations & maturity – SAMM.
• Awareness – Top 10, talks, cheat sheets.

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3. Short History of OWASP

• 2001 – OWASP founded by Mark Curphey as an open community for web app security.
• 2003 – First OWASP Top Ten published; quickly becomes the most referenced web AppSec document.
• Mid-2000s–2010s – New projects appear:
  ASVS (requirements standard), WSTG (testing guide), SAMM (maturity model), ZAP (DAST tool), Cheat Sheet Series.
• 2017 – Major Top Ten refresh (e.g., “Broken Authentication”, “Sensitive Data Exposure”).
• 2021 – New Top Ten version; “Insecure Design” and “Software and Data Integrity Failures” added, SSRF introduced as its own category. (OWASP Foundation)
• 2025 – Top Ten 2025 Release Candidate announced with updated categories such as “Software Supply Chain Failures” and “Mishandling of Exceptional Conditions”. (OWASP Foundation)

OWASP has grown from a small mailing list into a global standard-setting foundation for AppSec.

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4. What is the OWASP Top Ten?

The OWASP Top Ten is:

A standard awareness document that describes the most critical web application security risks, based on data from industry, bug bounties, and expert analysis. (OWASP Foundation)

4.1 What exactly is in it?

Current final version: OWASP Top 10: 2021. Categories: (OWASP Foundation)

1. A01 – Broken Access Control
2. A02 – Cryptographic Failures
3. A03 – Injection (includes XSS)
4. A04 – Insecure Design
5. A05 – Security Misconfiguration
6. A06 – Vulnerable and Outdated Components
7. A07 – Identification and Authentication Failures
8. A08 – Software and Data Integrity Failures
9. A09 – Security Logging and Monitoring Failures
10. A10 – Server-Side Request Forgery (SSRF)

There is also a 2025 Release Candidate list that introduces tweaks (e.g., a dedicated “Software Supply Chain Failures” category), but most organizations still treat 2021 as the stable baseline while they analyze 2025. (OWASP Foundation)

4.2 What the Top Ten is not

• It’s not a complete vulnerability catalog.
• It’s not a compliance checklist by itself.
• It’s not a testing guide or coding standard.

Think of it as:

“The 10 biggest families of mistakes you must understand and avoid.”

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5. Why the OWASP Top Ten Matters

5.1 For organizations

• Provides a minimum security bar for web apps.
• Serves as a benchmark in risk assessments and vendor evaluations.
• Many companies make a policy: “No app goes live with known OWASP Top 10 issues.”

5.2 For developers

• Easy way to understand what kinds of issues attackers actually exploit.
• Guides coding practices—e.g., use parameterized queries to avoid Injection, enforce least privilege and deny-by-default for Broken Access Control.
• Works well with Proactive Controls and Cheat Sheets (which say how to implement defenses).

5.3 For testers & auditors

• Provides a taxonomy for findings: “This issue is A01: Broken Access Control”.
• Forms the skeleton of test plans, often backed by the OWASP Web Security Testing Guide.

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6. How the OWASP Top Ten is Created

The Top Ten is data-driven but curated: (OWASP Foundation)

1. Data collection
   • Large sets of anonymized vulnerability data from security vendors, bug bounty platforms, consultancies, internal AppSec teams.
   • Data is mapped to CWEs (Common Weakness Enumerations).
2. Statistical analysis
   • Consider incidence rate (how many apps affected), exploitability, and impact.
   • Data factors like prevalence, detectability, and technical impact are weighed.
3. Survey & expert input
   • A worldwide community survey lets practitioners vote on what they see as most critical risks.
   • Some categories (e.g., earlier SSRF) came strongly from the survey, not just raw data.
4. Category creation & mapping
   • Many low-level CWEs are grouped into higher-level categories (e.g., XSS folded into Injection).
5. Draft → community review → final release
   • Release Candidate (RC) is published.
   • Feedback is collected and the final version is released.

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7. Deep Overview of the Top Ten 2021 (High Level)

You’ll probably teach each of these as its own section or lab, so here’s a compact “what + why + example” for each.

1. A01 – Broken Access Control
   • What: Users can act outside of intended permissions (e.g., horizontal escalations, vertical escalations, IDORs).
   • Impact: Data leakage, privilege escalation, account takeover of other users.
2. A02 – Cryptographic Failures
   • What: Wrong or missing crypto usage—weak algorithms, no encryption, hardcoded keys, non-TLS, poor key management.
   • Impact: Sensitive data exposure, tampering, impersonation.
3. A03 – Injection
   • What: Untrusted data is interpreted as code/commands (SQL, NoSQL, LDAP, OS commands, XSS, etc.).
   • Impact: Data theft, data corruption, remote code execution.
4. A04 – Insecure Design
   • What: Architectural and design flaws—no threat modeling, missing security controls, insecure workflows.
   • Impact: Systemically exploitable weaknesses that can’t be “patched” by code fixes alone.
5. A05 – Security Misconfiguration
   • What: Default configs, unnecessary features, verbose error messages, misconfigured headers, exposed admin endpoints.
   • Impact: Attackers exploit “configuration gaps” instead of code flaws.
6. A06 – Vulnerable and Outdated Components
   • What: Using libraries, frameworks, runtimes, and OS components with known CVEs or unsupported versions.
   • Impact: Known exploits become trivial paths into your system.
7. A07 – Identification and Authentication Failures
   • What: Weak login, session fixation, missing MFA, insecure password reset flows, bad session management.
   • Impact: Account takeover, unauthorized access.
8. A08 – Software and Data Integrity Failures
   • What: Trusting software updates, CI/CD pipelines, or data sources without integrity checks (e.g., dependency confusion, deserialization issues). (perallis.com)
   • Impact: Supply chain compromise, malicious code execution.
9. A09 – Security Logging and Monitoring Failures
   • What: Missing or poor logs, lack of alerting, no anomaly detection.
   • Impact: Breaches go undetected; forensics and incident response become extremely hard.
10. A10 – Server-Side Request Forgery (SSRF)
    • What: Application makes HTTP requests to arbitrary URLs based on user input without validation.
    • Impact: Attackers pivot into internal networks, cloud metadata endpoints, or sensitive internal services. (OWASP Foundation)

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8. OWASP Practices: Bringing Top Ten into Daily Work

8.1 Secure SDLC / DevSecOps practices

To actually “live” OWASP Top Ten in a team:

1. Define security requirements
   • Use OWASP ASVS to translate Top Ten risks into concrete requirements (e.g., “All access control checks must be server-side and enforced per function”).
2. Threat modeling
   • Lift “Insecure Design” from theory into practice: model threats at feature design time, not after release.
3. Coding standards
   • Adopt OWASP Proactive Controls (C1–C10) as internal secure coding guidelines (validate inputs, encode outputs, implement access control, protect data at rest/in transit, etc.).
4. Code review with security focus
   • Add “Top Ten checklist” to pull-request review templates.
5. Automated security scanning
   • SAST: finds injection, insecure APIs, etc.
   • SCA (Software Composition Analysis): maps dependencies to known CVEs (A06).
   • DAST: simulates attacks against running app (Injection, SSRF, auth flaws).
6. Security testing
   • Use OWASP WSTG to structure manual testing around Top Ten risks.
7. Logging & monitoring
   • Design robust logging, correlation IDs, alerts → addresses A09.

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9. OWASP Guidelines Ecosystem (Beyond Top Ten)

To make the tutorial complete, here’s how the other major OWASP standards relate to Top Ten:

9.1 ASVS – Application Security Verification Standard

• A detailed catalog of security requirements (L1, L2, L3).
• Each Top Ten risk corresponds to multiple ASVS controls (e.g., A01 maps to V4 Access Control, A07 to V2 Authentication).

9.2 Proactive Controls

• The “Top Ten things developers should do.”
• Example mappings:
  • C3 “Secure Database Access” → A03 Injection.
  • C6 “Implement Digital Identity” → A07.
  • C8 “Protect Data Everywhere” → A02 & A08.

9.3 WSTG – Web Security Testing Guide

• Practical test cases and checklists for each category.
• Example: Under Authorization Testing, you’ll implement tests to detect A01 Broken Access Control.

9.4 SAMM – Software Assurance Maturity Model

• Helps management plan how mature their software security process is (ad-hoc → defined → optimized).
• Ensures Top Ten and ASVS requirements are embedded in processes, not just one-time activities.

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10. OWASP Tools Relevant to Top Ten

10.1 Native OWASP tools

• OWASP ZAP
  • Interactive web proxy & DAST scanner.
  • Helps find injection, XSS, misconfigurations, auth issues.
• OWASP Dependency-Check / Dependency-Track
  • Scan libraries and frameworks for known vulnerabilities (A06).
• OWASP AMASS
  • Asset discovery for attack surface mapping.
• OWASP Juice Shop
  • Deliberately vulnerable app; perfect for Top Ten practice labs.
• OWASP Threat Dragon / PyTM (community)
  • Threat modeling, particularly for A04 Insecure Design.

10.2 Popular external tools that implement OWASP concepts

• SAST: SonarQube, Checkmarx, Fortify, etc.
• DAST: Burp Suite, Netsparker, etc.
• SCA: Snyk, GitHub Dependabot, JFrog Xray, etc.
• Runtime protection / WAF: ModSecurity with OWASP Core Rule Set, cloud WAFs.

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11. Process: Adopting OWASP Top Ten in an Organization

Here’s a practical adoption playbook you can teach as a step-by-step process.

Step 1 – Awareness & baseline

• Train developers, QA, DevOps on Top Ten with real examples.
• Run a quick scan (DAST + SCA) to get an initial vulnerability picture.

Step 2 – Policy & requirements

• Publish a simple policy: “New apps must not contain known OWASP Top Ten issues.”
• Use ASVS L1/L2 to define what “secure” means for each app.

Step 3 – Integrate into SDLC

• Add security checkpoints in:
  • Requirements (threat modeling)
  • Design reviews
  • Code reviews (Top Ten checklist)
  • Pre-release testing (WSTG-based tests)

Step 4 – Automate

• For each repo, integrate:
  • SCA (A06)
  • SAST (A01, A03, A07, etc.)
  • DAST (A05, A10, etc.) in pre-prod.

Step 5 – Improve logging and monitoring

• Ensure A09 is addressed by:
  • Centralized logs
  • Security event alerts
  • Incident runbooks.

Step 6 – Measure & mature with SAMM

• Use OWASP SAMM to assess current maturity and plan improvements.

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12. The OWASP Community & “Team”

OWASP isn’t a vendor; it’s a global community:

• Board of Directors – elected volunteers managing the foundation.
• Project leads – maintain Top Ten, ASVS, WSTG, SAMM, tools, etc.
• Chapter leaders – run city/regional meetups and events.
• Contributors – write docs, maintain tools, translate, review, gather data.
• Sponsors – companies that fund or contribute data and research.

OWASP Top Ten specifically has its own project team, which:

• Collects and analyzes vulnerability data.
• Organizes community surveys.
• Writes and reviews content.
• Engages with industry for feedback.

Anyone (including you) can:

• File issues / PRs on GitHub.
• Join mailing lists & Slack.
• Contribute test cases, examples, translations.

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13. Timeline of the OWASP Top Ten

A quick historical evolution view you can use as a slide:

Year	Version	Highlights
2003	First Top 10	Initial awareness list for web apps.
2004	Update	Early refinements based on feedback.
2007	Major refresh	Better categorization, more data-driven.
2010	New edition	XSS, Injection, CSRF, etc. mainstreamed.
2013	Update	“Sensitive Data Exposure”, “Using components with known vulnerabilities.”
2017	2017 Top 10	Added “Insufficient Logging & Monitoring”, “Insecure Deserialization”.
2021	2021 Top 10	New categories: “Insecure Design”, “Software and Data Integrity Failures”, SSRF; XSS folded into Injection. (OWASP Foundation)
2025	2025 RC	Shifts toward supply chain, operations, exception handling; “Software Supply Chain Failures” appears as its own category. (OWASP Foundation)

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14. Added Section – How to Learn & Teach OWASP Top Ten (Recommended Roadmap)

This is the “missing” piece that ties everything into a practical study / training path.

14.1 For self-study

1. Week 1–2 – Foundations
   • Read the OWASP Top 10: 2021 Introduction & category pages. (OWASP Foundation)
   • Map each category to one or two memorable real-world incidents.
2. Week 3–4 – Implementation
   • For each category:
     • Find the matching Proactive Controls item.
     • Identify matching ASVS controls (e.g., V2, V4, V5).
3. Week 5–6 – Testing
   • Study the WSTG sections corresponding to each Top Ten category.
   • Practice simple tests with a lab app (e.g., OWASP Juice Shop).
4. Week 7+ – Maturity & scale
   • Read SAMM summary; think how to embed Top Ten into org processes.

14.2 For training others (like your courses)

Structure your course into three blocks:

• Block A – Concepts (Top Ten + high-level OWASP overview)
• Block B – Implementation (Proactive Controls, ASVS, secure coding labs)
• Block C – Testing & Maturity (WSTG, SAMM, DevSecOps integration)

Within each block, repeatedly connect:

“This vulnerability (Top Ten) → these controls (ASVS/Proactive) → these tests (WSTG) → these processes (SAMM).”

This makes the training cohesive and enterprise-friendly.

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15. Final Summary

• OWASP is the global open standard body for application security.
• The OWASP Top Ten is the starting point: a curated list of the most critical web app security risks.
• It’s built using real data, expert input, and community review.
• For serious AppSec, Top Ten should be combined with:
  • ASVS (requirements),
  • Proactive Controls + Cheat Sheets (developer guidance),
  • WSTG (testing), and
  • SAMM (maturity and governance).
• Proper adoption means:
  • Training → Policy → Secure SDLC → Automation → Monitoring → Maturity.