Desktop Application Security in C#

DAY 1

Cyber security basics

• What is security?
• Threat and risk
• Cyber security threat types
• Consequences of insecure software
  • Constraints and the market
  • The dark side
• Categorization of bugs
  • The Seven Pernicious Kingdoms
  • Common Weakness Enumeration (CWE)
  • CWE Top 25 Most Dangerous Software Errors

Input validation

• Input validation principles
  • Blacklists and whitelists
  • Data validation techniques
  • What to validate – the attack surface
  • Where to validate – defense in depth
  • How to validate – validation vs transformations
  • Output sanitization
  • Encoding challenges
  • 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
    • Script injection
  • General protection best practices
• 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
  • Path traversal-related examples
  • Lab – Path traversal
  • Additional challenges in Windows
  • Path traversal best practices
• 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

DAY 2

Security features

• Authentication
  • Authentication basics
  • Multi-factor authentication
  • Authentication weaknesses – spoofing
  • Case study – PayPal 2FA bypass
  • User interface best practices
  • Password management
    • Inbound password management
      • Storing account passwords
      • Password in transit
      • Lab – Is just hashing passwords enough?
      • Dictionary attacks and brute forcing
      • Salting
      • Adaptive hash functions for password storage
      • Password policy
        • NIST authenticator requirements for memorized secrets
        • Password length
        • Password hardening
        • Using passphrases
        • Lab – Applying a password policy
      • Case study – The Ashley Madison data breach
        • The dictionary attack
        • The ultimate crack
        • Exploitation and the lessons learned
      • Password database migration
    • 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
        • Sensitive data in memory
• Authorization
  • Access control basics
• Information exposure
  • Exposure through extracted data and aggregation
  • Case study – Strava data exposure
  • System information leakage
    • Leaking system information
  • Information exposure best practices
• .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
    • Impersonation
    • Lab – Role-based security
  • Protecting .NET code and applications
    • Code signing
• UI security
  • UI security principles
  • Sensitive information in the user interface
  • Lab – Extracting password from the UI
  • Misinterpretation of UI features or actions
  • Insufficient UI feedback
  • Relying on hidden or disabled UI element
  • Insufficient anti-automation

Time and state

• Race conditions
  • Race condition in object data members
    • Lab – Singleton member fields
  • File race condition
    • Time of check to time of usage – TOCTTOU
    • Insecure temporary file
  • Database race conditions
  • Avoiding race conditions in C#

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
  • Catching and throwing SystemExceptions
  • Lab – Exception handling mess

DAY 3

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#
    • Case study – Equifax credit account freeze
    • Lab – Using random numbers in C#
  • Hashing
    • Hashing basics
    • Common hashing mistakes
    • 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
    • ProtectedMemory and ProtectedData
    • Lab – Symmetric encryption in C#
    • Asymmetric encryption
      • The RSA algorithm
        • Using RSA – best practices
        • RSA in C#
        • Lab – Using RSA in C#
      • Elliptic Curve Cryptography
        • The ECC algorithm
        • Using ECC – best practices
      • 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
    • Digital signature with ECC
    • Digital signature in C#
    • Lab – Digital signature in C#
• Public Key Infrastructure (PKI)
  • Some further key management challenges
  • Certificates
    • Chain of trust
    • Certificate management – best practices

Common software security weaknesses

• Code quality
  • Data handling
    • Initialization and cleanup
      • Class initialization cycles
      • Lab – Initialization cycles
    • Unreleased resource
  • Object oriented programming pitfalls
    • Accessibility modifiers
      • Are accessibility modifiers a security feature?
      • Accessibility modifiers – best practices
    • Inheritance and overriding
    • Mutability
      • Lab – Mutable object
      • Readonly collections
• Denial of service
  • Denial of Service
  • Resource exhaustion
  • Cash overflow
  • Flooding
  • Algorithm complexity issues
    • Regular expression denial of service (ReDoS)
      • Lab – Regular expression denial of service (ReDoS)
      • Dealing with ReDoS
    • Hashtable collision
      • How hashtables work?
      • Hash collision in case of hashtables
      • Hashtable collision in C#

Using vulnerable components

• 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 Schröder
• And now what?
  • Software security sources and further reading
  • .NET and C# resources