Secure coding in C and C++ for medical devices

Your medical device written in C and 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 -231? Because that’s what the bad guys will do – and the list is far from complete. The most important concern in the healthcare industry is naturally safety. However, once isolated medical devices became highly connected to date, which poses new kinds of security risks: from exposing sensitive patient information to denial of service. And remember, there is no safety without security! 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 medical devices developed in C and C++, and extended by core programming issues, discussing security pitfalls of these languages. So that you are prepared for the forces of the dark side. So that nothing unexpected happens. Nothing.

Outline:

Cyber security basics
Buffer overflow
Memory management hardening
Common software security weaknesses
Using vulnerable components
Security testing
Wrap up

Sector:

Healthcare, Medical devices

Objective list:

Getting familiar with essential cyber security concepts
Learning about security specialties of the healthcare sector
Identify vulnerabilities and their consequences
Learn the security best practices in C and C++
Input validation approaches and principles
Managing vulnerabilities in third party components
Understanding security testing methodology and approaches
Getting familiar with common security testing techniques and tools

Audience:

C/C++ developers developing medical devices

Prerequisites:

General C/C++ development

Course outline:

Cyber security basics

What is security?
Threat and risk
Cyber security threat types
Consequences of insecure software
- Constraints and the market
- The dark side
Regulations and standards
- Regulations for healthcare information systems
  - HIPAA
  - HIPAA and secure coding
  - GDPR
- Regulations for medical devices
  - Regulations and standards for medical devices
  - Relevance of embedded / industrial control standards
  - UL 2900
  - ISA and IEC 62443
  - NIST Guide to Industrial Control Systems (ICS) Security
Cyber security in the healthcare sector
- Threats and trends in healthcare
- Threats to medical devices
- The problem of legacy systems

Buffer overflow

Assembly basics and calling conventions
- x64 assembly essentials
- Registers and addressing
- Most common instructions
- Calling conventions on x64
  - Calling convention – what it is all about
  - The stack frame
  - Stacked function calls
Memory management vulnerabilities
- Memory management and security
- Vulnerabilities in the real world
- Buffer security issues
- Buffer overflow on the stack
  - Buffer overflow on the stack – stack smashing
  - Exploitation – Hijacking the control flow
  - Lab – Buffer overflow 101, code reuse
  - Exploitation – Arbitrary code execution
  - Injecting shellcode
  - Lab – Code injection, exploitation with shellcode
  - Case study – Stack BOF in boot file handling of MQX DHCP client
- Buffer overflow on the heap
  - Unsafe unlinking
  - Case study – Heap BOF in VxWorks DHCP options parsing
  - Case study – Heartbleed
- Pointer manipulation
  - Modification of jump tables
  - Overwriting function pointers
Best practices and some typical mistakes
- Unsafe functions
- Dealing with unsafe functions
- Lab – Fixing buffer overflow
- What’s the problem with asctime()?
- Lab – The problem with asctime()
- Using std::string in C++

Buffer overflow

Some typical mistakes leading to BOF
- Unterminated strings
- readlink() and string termination
- Manipulating C-style strings in C++
- Malicious string termination
- Lab – String termination confusion
- String length calculation mistakes
- Off-by-one errors
- Case study – Off-by-one error in VxWorks TCP ‘Urgent Data’ parsing
- Allocating nothing

Memory management hardening

Securing the toolchain
- Securing the toolchain in C and C++
- Compiler warnings and security
- Using FORTIFY_SOURCE
- Lab – Effects of FORTIFY
- AddressSanitizer (ASan)
  - Using AddressSanitizer (ASan)
  - ASan changes to the prologue
  - ASan changes to memory read/write operations
  - ASan changes to the epilogue
  - Lab – Using AddressSanitizer
- RELRO protection against GOT hijacking
- Heap overflow protection
- Stack smashing protection
  - Detecting BoF with a stack canary
  - Argument cloning
  - Stack smashing protection on various platforms
  - SSP changes to the prologue and epilogue
  - Lab – Effects of stack smashing protection
  - Bypassing stack smashing protection
Runtime protections
- Runtime instrumentation
- Address Space Layout Randomization (ASLR)
  - ASLR on various platforms
  - Lab – Effects of ASLR
  - Circumventing ASLR – NOP sleds
  - Heap spraying
- Non-executable memory areas
  - The NX bit
  - Write XOR Execute (W^X)
  - NX on various platforms
  - Lab – Effects of NX
  - NX circumvention – Code reuse attacks
    - Return-to-libc / arc injection
  - Return Oriented Programming (ROP)
    - Lab – ROP demonstration
    - Protection against ROP

Common software security weaknesses

Security features
- Authentication
  - Authentication basics
  - Multi-factor authentication
  - Authentication weaknesses – spoofing
  - Case study – Missing authentication in Alaris TIVA
  - 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
    - Case study – The Ashley Madison data breach
      - The dictionary attack
      - The ultimate crack
      - Exploitation and the lessons learned
    - Password database migration
- Authorization
  - Access control basics
  - Case study – Broken authorization in Conexus protocol for Medtronic devices
  - File system access control
    - Improper file system access control
    - Ownership
    - chroot jail
    - Using umask()
    - Linux filesystem
    - LDAP
    - Case study – Insecure file permissions in McKesson Cardiology 13.x / 14.x

Common software security weaknesses

Security features
- Authentication
- Password management
  - Outbound password management
    - Hard coded passwords
    - Best practices
    - Lab – Hardcoded password
    - Case study – Compromising Abbott FreeStyle Libre sensors via NFC
    - Protecting sensitive information in memory
      - Challenges in protecting memory
      - Heap inspection
      - Compiler optimization challenges
      - Lab – Zeroization challenges
      - Sensitive info in non-locked memory

Common software security weaknesses

Input validation
- Input validation principles
  - Blacklists and whitelists
  - Data validation techniques
  - Case study – Missing input validation in Natus Xltek NeuroWorks 8
  - 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 – Shellshock
      - Lab – Shellshock
      - Case study – Command injection in GE Healthcare MobileLink
    - Process control – library injection
      - DLL hijacking
      - Lab – DLL hijacking
      - Case study – DLL injection in Vyaire Medical CareFusion Upgrade Utility
- Integer handling problems
  - Representing signed numbers
  - Integer visualization
  - Integer promotion
  - Integer overflow
  - Lab – Integer overflow
  - Signed / unsigned confusion
  - Lab – Signed / unsigned confusion
  - Integer truncation
  - Lab – Integer truncation
  - Case study – WannaCry
  - Best practices
    - Upcasting
    - Precondition testing
    - Postcondition testing
    - Using big integer libraries
    - Best practices in C
    - UBSan changes to arithmetics
    - Lab – Handling integer overflow on the toolchain level in C/C++
    - Best practices in C++
    - Lab – Integer handling best practices in C++
- Files and streams
  - Path traversal
  - Path traversal-related examples
  - Lab – Path traversal
  - Path traversal best practices
  - Lab – Path canonicalization
- Format string issues
  - The problem with printf()
  - Lab – Exploiting format string

Common software security weaknesses

Time and state
- Race conditions
  - Race condition in object data members
    - Case study – State confusion in VxWorks IPNet stack
  - File race condition
    - Time of check to time of usage – TOCTTOU
    - Lab – TOCTTOU
    - Insecure temporary file
  - Potential race conditions in C/C++
    - Race condition in signal handling
    - Forking
    - Bit-field access
Errors
- Error and exception handling principles
- Error handling
  - Returning a misleading status code
  - Error handling in C
  - Error handling in C++
  - Using std::optional safely
  - Information exposure through error reporting
- Exception handling
  - In the catch block. And now what?
  - Empty catch block
  - Exception handling in C++
  - Lab – Exception handling mess
Code quality
- Data handling
  - Type mismatch
  - Lab – Type mismatch
  - Initialization and cleanup
    - Constructors and destructors
    - Initialization of static objects
    - Lab – Initialization cycles
  - Unreleased resource
    - Case study – Unreleased resource in VxWorks TCP ‘Urgent Data’ parsing
    - Array disposal in C++
    - Lab – Mixing delete and delete[]
- Control flow
  - Incorrect block delimitation
  - Dead code
  - Leftover debug code
  - Backdoors, dev functions and other undocumented functions
  - Using if-then-else and switch defensively
- Signal handling
  - Signal handlers
  - Best practices
- Object oriented programming pitfalls
  - Inheritance and object slicing
  - Implementing the copy operator
  - The copy operator and mutability
  - Mutability
    - Mutable predicate function objects
    - Lab – Mutable predicate function object
- Memory and pointers
  - Memory and pointer issues
  - Pointer handling pitfalls
  - Alignment
  - Null pointers
    - NULL dereference
    - NULL dereference in pointer-to-member operators
    - Case study – NULL dereference in VxWorks IGMP parsing
  - Pointer usage in C and C++
    - Use after free
    - Lab – Use after free
    - Lab – Runtime instrumentation
    - Double free
    - Memory leak
    - Smart pointers and RAII
    - Smart pointer challenges
    - Incorrect pointer arithmetics
- File I/O
  - Working with file descriptors, structures and objects
  - File reading and writing
  - File access functions and methods

Using vulnerable components

Assessing the environment
Hardening
Case study – Supply chain attack on Alaris Gateway Workstation
Vulnerability management
- Patch management
- Bug bounty programs
- Vulnerability databases
- Vulnerability rating – CVSS
- Lab – Finding vulnerabilities in third-party components
- DevOps, the build process and CI / CD
- Insecure compiler optimization

Security testing

Security testing vs functional testing
Manual and automated methods
Security testing techniques and tools
- Code analysis
  - Security aspects of code review
  - 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)
  - Fuzzing
    - Fuzzing techniques
    - Fuzzing – Observing the process

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
- C and C++ resources

Kursavgift:	25,900 NOK
Kurset inkluderer:	Course documentation and exercises. Lunch and refreshments for in class events only.
Timer	09.00-1700
Varighet:	4 dager
Språk	English

Secure coding in C and C++ for medical devices

Outline:

Sector:

Objective list:

Audience:

Prerequisites:

Course outline:

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