Anti-Tampering

• Detecting Whether the Current Process is Being ptrace()d (Linux Specific)
  Problem: The linux tracing facility is the ptrace(2) system call. A program with sensitive internals may wish to change its behaviour if it is being traced. The problem is how to detect if a process is being ptraced.

General / Miscellaneous

• Watching Out for API Differences (And Using *snprintf Properly in C)
  Problem: A change in API semantics that doesn't break the call by changing the signature can lead to insecurities when a developer tries to call one version of the API but gets a different version. This can be a problem when APIs are slightly different between platforms.

Input Validation

Exerpts from Secure Programming Cookbook for C and C++ by John Viega and Matt Messier:

• Sanitizing the Environment
  Supplement to Recipe 1.1 beginning on page 6.
  Problem: You wish to harden the code in case an OS doesn't limit environment size.
• Understanding Basic Data Validation Techniques
  Excerpt from Recipe 3.1 beginning on page 71.
  Problem: You have data coming into your application, and you would like to filter or reject data that might be malicious.
• Another Input Validation Principle: Decode First
  Supplement to Recipe 3.1 beginning on page 71.
  Problem: You have data coming into your application, and you would like to filter or reject data that may be malicious. The data may need to be decoded, truncated or so on.
• Preventing Buffer Overflows
  Excerpt from Recipe 3.3 beginning on page 78.
  Problem: C and C++ do not perform array-bounds checking, which turns out to be a security-critical issue, particularly in handling strings. The risks increase even more dramatically when user-controlled data is on the program stack (i.e., is a local variable).
• Using Environment Variables Securely
  Supplement to Recipe 3.6 beginning on page 92.
  Problem: You wish to harden the code in case an OS doesn't limit environment size.
• Evaluating URL Encodings in C and C++
  Excerpt from Recipe 3.8 beginning on page 99.
  Problem: You need to decode a Uniform Resource Locator (URL).
• Validating Email Addresses in C and C++
  Excerpt from Recipe 3.9 beginning on page 101.
  Problem: Your program accepts an email address as input, and you need to verify that the supplied address is valid.

---

• Avoiding malloc()/new-related integer overflows
  Problem: Integer overflows can lead to allocating too little memory, which can often result in an exploitable buffer overflow.
• Truncating Data Carefully in C and C++
  Problem: When avoiding buffer overflows by truncating data, there is the possibility of introducing new problems. Additionally, one should watch out for situations where an attacker can truncate data in a way the program doesn't expect.
• Validating Email Addresses in JavaScript
  Problem: Your program accepts an email address as input, and you need to verify that the supplied address is valid.
• Validating Email Addresses in Python
  Problem: Your program accepts an email address as input, and you need to verify that the supplied address is valid.

Public Key Infrastructure

Exerpts from Secure Programming Cookbook for C and C++ by John Viega and Matt Messier:

• Win32: Obtaining CRLs with CryptoAPI
  Supplement to Recipe 10.11 beginning on page 556.
  Problem: Recipe 10.11 in the book "Secure Programming Cookbook for C and C++" showed an example of how to retrieve CRLs from a CA specified as a URL in the extension properties of an X.509 Certificate. The code presented in book used its own "search" function to find a cRLDistributionPoints extension in the certificate, and the Win32 WinInet functions to download the CRL from an HTTP or HTTPS location. Other types of URLs are possible as well, including LDAP and FTP; however, the code presented in the book does not support anything other than HTTP and HTTPS.

Random Numbers

• Another shuffling algorithm
  Problem: Most shuffling algorithms people use aren't statistically fair. Fair ones tend to be subtle or complex. You want a shuffling algorithm that is fairly simple, unbiased, easy to demonstrate correct and programmatically verifiable.
• Using /dev/random from Python
  Problem: You are using Python and would like to have a source of cryptographically secure psuedo-random numbers.

Symmetric Cryptography

Exerpts from Secure Programming Cookbook for C and C++ by John Viega and Matt Messier:

• Knowing Which Ciphers to Avoid
  Supplement to Recipe 5.2 beginning on page 156.
  Problem: You're using a library providing symmetric encryption ciphers, and want to know if any of them are to be avoided.

---

• Using a CBC-like mode without padding in C and C++ (CTS mode)
  Problem: You wish to use a block-based block cipher mode such as CBC (as opposed to a streaming mode), yet do not want to perform message padding.