Web application security masterclass in C#

Your Web 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.
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 C#, and extended by core programming issues, discussing security pitfalls of the C# language and the ASP.NET framework.
So that you are prepared for the forces of the dark side.
So that nothing unexpected happens.
Nothing.
Outline

Cyber security basics
The OWASP Top Ten 2021
Security testing
Wrap up

DAY 1Cyber security basics

What is security?
Threat and risk
Cyber security threat types – the CIA triad
Consequences of insecure software
Constraints and the market

 
The OWASP Top 10 2021
A01 – Broken Access Control

Access control basics
Missing or improper authorization
Failure to restrict URL access
Lab – 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
Open redirects and forwards- Case study – Unvalidated redirect at Epic Games- Open redirects and forwards – best practices
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- Data exposure best practices- Data masking- Privacy violation   - Privacy essentials   - Related standards, regulations and laws in brief   - Privacy violation and best practices- System information leakage   - Leaking system information   - Exposure through debug information   - Exposure through files and directories- Information leakage through side channels   - Exposure through side channels   - Side channels and covert channels- Information exposure best practices
Cryptography basics- Crypto APIs in C#- Elementary algorithms   - Random number generation      - Pseudo random number generators (PRNGs)      - Cryptographically strong PRNGs      - Seeding       - Weak and strong PRNGs       - Using random numbers in C#       - Lab – Using random numbers in C#       - True random number generators (TRNG)       - Case study – Equifax credit account freeze

DAY 2A02 – Cryptographic Failures (continued)

Cryptography for developers- Elementary algorithms   - 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   - Some further key management challenges
 Certificates- Certificates and PKI- X.509 certificates

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- 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
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       - Further XSS protection techniques       - Lab – XSS fix / stored       - Lab – XSS fix / reflected       - Client-side protection principles       - Additional protection layers – defense in depth

DAY 3A03 – Injection (continued)

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- Output sanitization- Encoding challenges- Unicode challenges- Lab – Encoding challenges- Validation with regex- 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      - Reflection without validation      - Lab – Unsafe reflection

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- Lab – Client-side security- Same Origin Policy   - Simple request   - Preflight request   - Cross-Origin Resource Sharing (CORS)   - Relaxing the Same Origin Policy- Frame sandboxing   - Cross-Frame Scripting (XFS) attacks   - Lab – Clickjacking   - Clickjacking beyond hijacking a click   - Clickjacking protection best practices   - Lab – Using CSP to prevent clickjacking- Some further best practices   - HTML5 security best practices   - CSS security best practices   - Ajax security best practices- JSON security   - JSON validation   - JSON injection   - Dangers of JSONP   - JSON/JavaScript hijacking   - Best practices   - Case study – ReactJS vulnerability in HackerOne- XML security   - XML validation   - XML injection     - XPath injection     - Blind XPath injection

DAY 4A05 – Security Misconfiguration

Configuration principles
Server misconfiguration
ASP.NET and IIS configuration best practices- ASP.NET configuration- IIS configuration
Cookie security- Cookie attributes
XML entities- DTD and the entities- Entity expansion- 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
Vulnerability management- Patch management- Vulnerability databases- Lab – Finding vulnerabilities in third-party components- DevOps, the build process and CI / CD- Dependency checking in C#- Lab – Detecting vulnerable components

A07 – Identification and Authentication Failures

Authentication- Authentication basics- Multi-factor authentication- Case study – PayPal 2FA bypass
Session management- Session management essentials- Why do we protect session IDs – Session hijacking- Session fixation
Password management- Inbound password management   - Storing account passwords   - Password in transit   - Lab – Is just hashing passwords enough?   - Dictionary attacks and brute forcin   - Salting   - Adaptive hash functions for password storage   - Lab – Using adaptive hash functions in C#   - Password policy      - NIST authenticator requirements for memorized secrets   - Case study – The Ashley Madison data breach      - The dictionary attack      - The ultimate crack      - Exploitation and the lessons learned- Outbound password management   - Hard coded passwords   - Best practices   - Lab – Hardcoded password

A08 – Software and Data Integrity Failures

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- Digital signature in C#   - Lab – Digital signature with ECDSA in C#

DAY 5A08 – Software and Data Integrity Failures (continued)

Subresource integrity- Importing JavaScript- Lab – Importing JavaScript- Case study – The British Airways data breach
Insecure deserialization- 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   - Summary – POP best practices

A09 – Security Logging and Monitoring Failures

Logging and monitoring principles
Insufficient logging
Case study – Plaintext passwords at Facebook
Logging best practices
C# logging best practices
Monitoring best practices
Firewalls and Web Application Firewalls (WAF)
Intrusion detection and prevention
Case study – The Marriott Starwood data breach

A10 – Server-Side Request Forgery (SSRF)

Server-side Request Forgery (SSRF)
Case study – SSRF and the Capital One breach

Web application security beyond the Top Ten

Code quality- Code quality and security- Data handling   - Arrays and ToString()- Function return values   - Unchecked Return Value- Initialization and cleanup   - Uninitialized variable   - Class initialization cycles   - Lab – Initialization cycles- Unreleased resource   - Unreleased resource – Database   - Unreleased resource – Synchronization   - Unreleased resource – Various- Language elements   - Using dangerous language elements   - Using obsolete language elements   - Portability flaw- Object oriented programming pitfalls   - Accessibility modifiers     - Are accessibility modifiers a security feature?     - Accessibility modifiers – best practices   - Inheritance and overriding   - Implementing Equals()   - Mutability       - Lab – Mutable object       - Readonly collections- Memory and pointers   - Garbage collection   - Null pointers     - null dereference     - null dereference – best practices     - Using Nullable type parameters     - Memory leak     - Unmanaged memory leaks
Denial of service- Flooding- Resource exhaustion- Sustained client engagement- Denial of service problems in C#- Infinite loop- Economic Denial of Sustainability (EDoS)- Amplification   - Other amplification examples- Algorithm complexity issues   - Regular expression denial of service (ReDoS)     - Lab – ReDoS in C#     - Dealing with ReDoS

Security testing

Security testing techniques and tools- Code analysis   - Static Application Security Testing (SAST)   - Lab – Using static analysis tools- Dynamic analysis   - Security testing at runtime   - Penetration testing   - Stress testing   - Dynamic analysis tools      - Dynamic Application Security Testing (DAST)      - Web vulnerability scanners      - Lab – Using web vulnerability scanners      - SQL injection tools   - Fuzzing

Wrap up

Secure coding principles- Principles of robust programming by Matt Bishop
And now what?- Software security sources and further reading- NET and C# resources