Desktop application security in C#

3 days
On-site or online

27 Labs


7 Case Studies




C# developers working on desktop applications


General C# development

Standards and references

CWE and Fortify Taxonomy

Group size

12 participants


  • Cyber security basics
  • Input validation
  • Security features
  • Errors
  • Denial of service
  • Cryptography for developers
  • Common software security weaknesses
  • Using vulnerable components
  • Wrap up

What you will learn

  • Getting familiar with essential cyber security concepts
  • Input validation approaches and principles
  • Identify vulnerabilities and their consequences
  • Learn the security best practices in C#
  • Understanding how cryptography supports security
  • Learning how to use cryptographic APIs correctly in C#
  • Managing vulnerabilities in third party components


Your application written in C# 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.

All this is put in the context of C#, and extended by core programming issues, discussing security pitfalls of the C# language and the .NET framework.

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

So that nothing unexpected happens.


Table of contents

  • Cyber security basics
  • Input validation
    • Input validation principles
    • Denylists and allowlists
    • What to validate – the attack surface
    • Where to validate – defense in depth
    • When to validate – validation vs transformations
    • Validation with regex
    • Injection
      • Injection principles
      • Injection attacks
      • Code injection
        • 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 – Command injection via ping
    • Integer handling problems
      • Representing signed numbers
      • Integer visualization
      • Integer overflow
      • Lab – Integer overflow
      • Signed / unsigned confusion
      • Case study – The Stockholm Stock Exchange
      • Lab – Signed / unsigned confusion
      • Integer truncation
      • Best practices
        • Upcasting
        • Precondition testing
        • Postcondition testing
        • Using big integer libraries
        • Integer handling in C#
        • Lab – Checked arithmetics
    • Files and streams
      • Path traversal
      • Lab – Path traversal
      • Path traversal-related examples
      • Additional challenges in Windows
      • Virtual resources
      • Path traversal best practices
      • Lab – Path canonicalization
    • Unsafe reflection
      • Reflection without validation
      • Lab – Unsafe reflection
    • Unsafe native code
      • Native code dependence
      • Lab – Unsafe native code
      • Best practices for dealing with native code
  • Security features
    • Authentication
      • Authentication basics
      • Multi-factor authentication
      • Authentication weaknesses
      • Password management
        • Inbound password management
        • Outbound password management
          • Hard coded passwords
          • Best practices
          • Lab – Hardcoded password
          • Protecting sensitive information in memory
            • Challenges in protecting memory
            • Storing sensitive data in memory
    • Information exposure
      • Exposure through extracted data and aggregation
      • Case study – Strava data exposure
    • Platform security
      • .NET platform security
        • Code Access Security
          • Code Access Security and Evidence
          • Application Domains and Permissions
          • The Stack Walk
          • Lab – Code Access Security
        • The transparency model
          • Lab – The transparency model
        • Role-based security
          • Principal and identity
          • Role-based permissions
          • Lab – Role-based security
  • Errors
    • Error and exception handling principles
    • Error handling
      • Returning a misleading status code
      • Information exposure through error reporting
    • Exception handling
      • In the catch block. And now what?
      • Catching NullReferenceException
      • Empty catch block
      • Lab – Exception handling mess
  • Denial of service
    • Flooding
    • Resource exhaustion
    • Sustained client engagement
    • Algorithm complexity issues
      • Regular expression denial of service (ReDoS)
        • Lab – ReDoS in C#
        • Dealing with ReDoS
  • Cryptography for developers
    • Cryptography basics
    • Crypto APIs in C#
    • Elementary algorithms
      • Random number generation
        • Pseudo random number generators (PRNGs)
        • Cryptographically strong PRNGs
        • Weak and strong PRNGs
        • Using random numbers in C#
        • Lab – Using random numbers in C#
        • Case study – Equifax credit account freeze
      • Hashing
        • Hashing basics
        • Hashing in C#
        • Lab – Hashing in C#
    • Confidentiality protection
      • Symmetric encryption
        • Block ciphers
        • Modes of operation
        • Modes of operation and IV – best practices
        • Symmetric encryption in C#
        • Symmetric encryption in C# with streams
        • Lab – Symmetric encryption in C#
      • Asymmetric encryption
        • The RSA algorithm
          • Using RSA – best practices
          • RSA in C#
      • Combining symmetric and asymmetric algorithms
        • Integrity protection
      • Message Authentication Code (MAC)
        • Calculating HMAC in C#
        • Lab – Calculating MAC in C#
      • Digital signature
        • Digital signature with RSA
        • Elliptic Curve Cryptography
          • ECC basics
          • Digital signature with ECC
          • Lab – Digital signature with ECDSA in C#
  • Common software security weaknesses
    • Code quality
      • Code quality and security
      • Data handling
        • Initialization and cleanup
          • Class initialization cycles
          • Lab – Initialization cycles
      • Object oriented programming pitfalls
        • Inheritance and overriding
        • Mutability
          • Lab – Mutable object
          • Readonly collections
      • Serialization
        • Serialization and deserialization challenges
        • Integrity – deserializing untrusted streams
        • Integrity – deserialization best practices
        • Property Oriented Programming (POP)
          • Creating a POP payload
          • Lab – Creating a POP payload
          • Lab – Using the POP payload
  • Using vulnerable components
    • Case study – The British Airways data breach
    • Vulnerability management
      • Patch management
      • Vulnerability databases
      • Lab – Finding vulnerabilities in third-party components
  • Wrap up
    • Secure coding principles
      • Principles of robust programming by Matt Bishop
      • Secure design principles of Saltzer and Schroeder
    • And now what?
      • Software security sources and further reading
      • .NET and C# 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
Customized course

Tailor a course to your preferences

  • Send us a brief description of your business’s training needs
  • Include your contact information
  • One of our colleagues will be in touch to schedule a free consultation about training requirements


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