Web application security in Python

3 days
On-site or online

27 Labs


12 Case Studies




Python developers working on Web applications


General Python and Web development

Standards and references

OWASP, CWE and Fortify Taxonomy

Group size

12 participants


  • Cyber security basics
  • The OWASP Top Ten 2021
  • Wrap up

What you will learn

  • Getting familiar with essential cyber security concepts
  • Understanding how cryptography supports security
  • Learning how to use cryptographic APIs correctly in Python
  • Understanding Web application security issues
  • Detailed analysis of the OWASP Top Ten elements
  • Putting Web application security in the context of Python
  • Going beyond the low hanging fruits
  • Managing vulnerabilities in third party components


Your Web application written in Python works as intended, so you are done, right? But did you consider feeding in incorrect values? 16Gbs of data? A null? An apostrophe? Negative numbers, or specifically -1 or -2^31? Because that’s what the bad guys will do – and the list is far from complete.

Handling security needs a healthy level of paranoia, and this is what this course provides: a strong emotional engagement by lots of hands-on labs and stories from real life, all to substantially improve code hygiene. Mistakes, consequences, and best practices are our blood, sweat and tears.

The curriculum goes through the common Web application security issues following the OWASP Top Ten but goes far beyond it both in coverage and the details.All this is put in the context of Python, and extended by core programming issues, discussing security pitfalls of the programming language.

So that you are prepared for the forces of the dark side.

So that nothing unexpected happens.


They said about us

Great and unique platform

Labs are awesome. Good prompting from the Cydrill Sergeant platform.

Employee at a Forecast Unit , August, 2019

Asheville, NC, USA

Table of contents

  • Cyber security basics
  • The OWASP Top Ten 2021
    • The OWASP Top 10 2021
    • A01 – Broken Access Control
      • Access control basics
      • Failure to restrict URL access
      • Confused deputy
        • Insecure direct object reference (IDOR)
        • Path traversal
        • Lab – Insecure Direct Object Reference
        • Path traversal best practices
        • Authorization bypass through user-controlled keys
        • Case study – Authorization bypass on Facebook
        • Lab – Horizontal authorization
      • File upload
        • Unrestricted file upload
        • Good practices
        • Lab – Unrestricted file upload
      • Cross-site Request Forgery (CSRF)
        • Lab – Cross-site Request Forgery
        • CSRF best practices
        • CSRF defense in depth
        • Lab – CSRF protection with tokens
    • A02 – Cryptographic Failures
      • Information exposure
        • Exposure through extracted data and aggregation
        • Case study – Strava data exposure
      • Cryptography for developers
        • Cryptography basics
        • Cryptography in Python
        • Elementary algorithms
          • Random number generation
            • Pseudo random number generators (PRNGs)
            • Cryptographically strong PRNGs
            • Using virtual random streams
            • Weak PRNGs
            • Using random numbers
            • Lab – Using random numbers in Python
            • Case study – Equifax credit account freeze
          • Hashing
            • Hashing basics
            • Hashing in Python
            • Lab – Hashing in Python
        • Confidentiality protection
          • Symmetric encryption
            • Block ciphers
            • Modes of operation
            • Modes of operation and IV – best practices
            • Symmetric encryption in Python
            • Lab – Symmetric encryption in Python
          • Asymmetric encryption
          • Combining symmetric and asymmetric algorithms
  • The OWASP Top Ten 2021
    • A03 – Injection
      • Injection principles
      • Injection attacks
      • SQL injection
        • SQL injection basics
        • Lab – SQL injection
        • Attack techniques
        • Content-based blind SQL injection
        • Time-based blind SQL injection
      • SQL injection best practices
        • Input validation
        • Parameterized queries
        • Lab – Using prepared statements
        • Additional considerations
        • Case study – Hacking Fortnite accounts
      • Code injection
        • Code injection via input()
        • OS command injection
          • Lab – Command injection
          • OS command injection best practices
          • Avoiding command injection with the right APIs
          • Lab – Command injection best practices
          • Case study – Shellshock
          • Lab – Shellshock
      • HTML injection – Cross-site scripting (XSS)
        • Cross-site scripting basics
        • Cross-site scripting types
          • Persistent cross-site scripting
          • Reflected cross-site scripting
          • Client-side (DOM-based) cross-site scripting
        • Lab – Stored XSS
        • Lab – Reflected XSS
        • Case study – XSS in Fortnite accounts
        • XSS protection best practices
          • Protection principles – escaping
          • XSS protection APIs in Python
          • XSS protection in Jinja2
          • Lab – XSS fix / stored
          • Lab – XSS fix / reflected
          • Additional protection layers – defense in depth
    • A04 – Insecure Design
      • The STRIDE model of threats
      • Secure design principles of Saltzer and Schroeder
        • Economy of mechanism
        • Fail-safe defaults
        • Complete mediation
        • Open design
        • Separation of privilege
        • Least privilege
        • Least common mechanism
        • Psychological acceptability
      • Client-side security
        • Same Origin Policy
          • Simple request
          • Preflight request
          • Cross-Origin Resource Sharing (CORS)
          • Lab – Same-origin policy demo
        • Frame sandboxing
          • Cross-Frame Scripting (XFS) attacks
          • Lab – Clickjacking
          • Clickjacking beyond hijacking a click
          • Clickjacking protection best practices
          • Lab – Using CSP to prevent clickjacking
  • The OWASP Top Ten 2021
    • A05 – Security Misconfiguration
      • Configuration principles
      • Server misconfiguration
      • Python configuration best practices
        • Configuring Flask
      • Cookie security
        • Cookie attributes
      • XML entities
        • DTD and the entities
        • Entity expansion
        • Lab – Billion laughs attack
        • External Entity Attack (XXE)
          • File inclusion with external entities
          • Server-Side Request Forgery with external entities
          • Lab – External entity attack
          • Case study – XXE vulnerability in SAP Store
          • Preventing XXE
          • Lab – Prohibiting DTD
    • A06 – Vulnerable and Outdated Components
      • Using vulnerable components
      • Assessing the environment
      • Hardening
      • Untrusted functionality import
      • Malicious packages in Python
      • Vulnerability management
    • A07 – Identification and Authentication Failures
      • Authentication
        • Authentication basics
        • Multi-factor authentication
        • Authentication weaknesses
        • Case study – PayPal 2FA bypass
      • Session management
        • Session management essentials
        • Why do we protect session IDs – Session hijacking
        • Session fixation
        • Session ID best practices
        • Session handling in Flask
      • Password management
        • Inbound password management
    • A08 – Software and Data Integrity Failures
      • Integrity protection
        • Message Authentication Code (MAC)
          • MAC in Python
          • Lab – Calculating MAC in Python
        • Digital signature
      • Subresource integrity
        • Importing JavaScript
        • Lab – Importing JavaScript
        • Case study – The British Airways data breach
    • A10 – Server-Side Request Forgery (SSRF)
      • Server-side Request Forgery (SSRF)
      • Case study – SSRF and the Capital One breach
  • Wrap up
    • Secure coding principles
      • Principles of robust programming by Matt Bishop
    • And now what?
      • Software security sources and further reading
      • Python resources


3 days Session Price

2250 EUR / person

  • Live, instructor led classroom training
  • Discussion and insight into the hacker’s mindset
  • Hands-on practice using case studies based on high-profile hacks and live lab exercises
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