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attack-surface.md

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Attack Surface Analysis for weidai11/cryptopp

Attack Surface: Incorrect Algorithm/Mode Selection

  • Description: Choosing a cryptographically weak algorithm, an insecure mode of operation, or inappropriate parameters (key size, IV length, etc.) for the specific use case.
  • How Crypto++ Contributes: Crypto++ provides a vast array of algorithms and modes, increasing the chance of misconfiguration if developers aren't cryptographic experts. It allows insecure choices.
  • Example: Using DES (Data Encryption Standard) for new development, or using AES in ECB (Electronic Codebook) mode, which reveals patterns in the plaintext.
  • Impact: Complete compromise of confidentiality and/or integrity of the protected data. Attacker can decrypt data or forge messages.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developer: Follow cryptographic best practices (NIST, OWASP) rigorously. Document the rationale for all cryptographic choices. Use a configuration management system to enforce approved settings. Prioritize authenticated encryption (GCM, CCM, EAX). Conduct regular security reviews.

Attack Surface: Key Management Failures (Specific Crypto++ Interaction)

  • Description: Improper handling of cryptographic keys in the context of using Crypto++ for operations. This focuses on how keys are passed to and used within Crypto++ functions, not general key storage.
  • How Crypto++ Contributes: Crypto++ functions require keys as input (often as SecByteBlock or raw byte arrays). Incorrectly creating, passing, or handling these key representations within the application code, even if the key storage is secure, creates vulnerabilities.
  • Example: Using a weak key derivation function (KDF) with insufficient iterations before passing the derived key to a Crypto++ encryption function. Or, failing to zero out a SecByteBlock immediately after it's used with a Crypto++ function.
  • Impact: Complete compromise of all cryptographic operations relying on the mishandled key(s).
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developer: Use strong KDFs (PBKDF2, scrypt, Argon2) with appropriate parameters before using keys with Crypto++. Zero out memory containing keys immediately after use with Crypto++ functions (using SecByteBlock and secure memory wiping). Ensure correct key sizes and formats are used for the chosen Crypto++ algorithms.

Attack Surface: Random Number Generation Weakness

  • Description: Using a weak or improperly seeded random number generator (RNG) provided by Crypto++ for cryptographic operations.
  • How Crypto++ Contributes: Crypto++ offers various RNGs. If the application chooses a weak one or misuses a strong one (e.g., not checking for errors, insufficient seeding), security is compromised.
  • Example: Using a predictable PRNG without proper seeding, or failing to check the return value of AutoSeededRandomPool to ensure it successfully generated random data.
  • Impact: Predictable keys, IVs, nonces, etc., leading to complete compromise of cryptographic operations.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developer: Use a CSPRNG provided by Crypto++ (e.g., AutoSeededRandomPool, OS_GenerateRandomBlock). Verify the platform-specific seeding mechanism is robust. Always check the return values of RNG functions.

Attack Surface: Timing Attacks

  • Description: Exploiting variations in the execution time of Crypto++ cryptographic operations to deduce information about secret keys.
  • How Crypto++ Contributes: Some Crypto++ functions (especially those involving modular exponentiation or elliptic curves) may be vulnerable if not implemented with constant-time techniques. This is a direct property of the Crypto++ implementation.
  • Example: An attacker measuring the time it takes for a Crypto++ RSA decryption operation to potentially recover bits of the private key.
  • Impact: Partial or complete key recovery, leading to compromise of confidentiality and/or integrity.
  • Risk Severity: High (often requires close proximity or specialized access)
  • Mitigation Strategies:
    • Developer: Be aware of potentially vulnerable functions. Use constant-time implementations where available (check Crypto++ documentation). Consider "blinding" techniques (but implement with extreme care). Keep Crypto++ updated.

Attack Surface: API Misuse

  • Description: Incorrectly using the Crypto++ API, leading to subtle but critical security flaws.
  • How Crypto++ Contributes: The Crypto++ API is complex, and misunderstandings can easily lead to vulnerabilities. This is a direct consequence of using the library.
  • Example: Reusing an IV/nonce with a stream cipher or a block cipher in a mode that requires unique IVs (like CTR, GCM), failing to authenticate ciphertext before decryption (padding oracle attacks), or mishandling exceptions thrown by Crypto++ functions.
  • Impact: Varies depending on the specific misuse, but can range from data corruption to complete compromise of confidentiality and/or integrity.
  • Risk Severity: High to Critical (depending on the specific misuse)
  • Mitigation Strategies:
    • Developer: Thoroughly understand the Crypto++ documentation. Write extensive unit tests specifically for cryptographic operations. Conduct code reviews with a focus on correct API usage. Create higher-level abstractions to encapsulate Crypto++ calls and reduce direct API interaction.

Attack Surface: Unpatched Crypto++ Vulnerabilities

  • Description: Exploiting known vulnerabilities in the specific version of Crypto++ being used.
  • How Crypto++ Contributes: Like any software, Crypto++ can have bugs. Older versions may contain known vulnerabilities. This is inherent to using any third-party library.
  • Example: A specific version of Crypto++ might have a flaw in its AES implementation that allows for a key recovery attack.
  • Impact: Depends on the specific vulnerability, but can range from denial-of-service to complete compromise.
  • Risk Severity: Variable (depends on the vulnerability), potentially Critical
  • Mitigation Strategies:
    • Developer: Keep Crypto++ up-to-date. Monitor security advisories and mailing lists. Consider using dependency management tools to automate updates.