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Threat Model Analysis for weidai11/cryptopp

Threat: Weak Cipher Suite Selection (Due to Developer Choice within Crypto++)

  • Description: Developers choose a weak or outdated cipher algorithm (e.g., DES, RC4) or a weak mode of operation (e.g., ECB) available within Crypto++ for encryption. An attacker could passively eavesdrop on encrypted communications or actively manipulate encrypted data. This is a direct misuse of Crypto++'s available options.
    • Impact:
      • Confidentiality breach: Sensitive data encrypted with weak ciphers can be decrypted.
      • Integrity violation: Data encrypted with weak modes (like ECB) can be altered.
      • Loss of user trust, legal/regulatory consequences.
    • Affected Crypto++ Component:
      • BlockCipher implementations (e.g., DES, AES, Blowfish)
      • StreamCipher implementations (e.g., RC4, Salsa20)
      • Mode of operation classes (e.g., ECB_Mode, CBC_Mode, CTR_Mode)
    • Risk Severity: High
    • Mitigation Strategies:
      • Enforce Strong Defaults: Configure the application to default to strong ciphers (AES-256, ChaCha20) and authenticated encryption (GCM, CCM).
      • Deprecate/Disable Weak Options: Remove or disable weak ciphers/modes in the build or via runtime checks.
      • Code Review and Static Analysis: Detect the use of weak primitives.
      • Developer Education: Train developers on appropriate algorithm/mode selection.

Threat: Padding Oracle Attack (CBC Mode Misuse within Crypto++)

  • Description: The application uses Crypto++'s CBC_Mode with padding (e.g., PKCS#7) but fails to handle padding errors correctly. An attacker sends crafted ciphertexts, observing error responses or timing differences to decrypt the ciphertext without the key. This is a direct misuse of the CBC_Mode implementation.
    • Impact:
      • Confidentiality breach: Decrypt arbitrary ciphertexts.
      • Potential for further attacks.
    • Affected Crypto++ Component:
      • CBC_Mode (specifically with padding)
      • Decryption functions within CBC_Mode
    • Risk Severity: High
    • Mitigation Strategies:
      • Use Authenticated Encryption: Prioritize GCM, CCM, or EAX, which are inherently resistant.
      • Constant-Time Padding Verification: If CBC must be used, implement constant-time padding verification. Review Crypto++'s implementation for constant-time guarantees.
      • Generic Error Handling: Return a generic error message, regardless of the padding error.

Threat: Key Derivation Weakness (Using Weak Crypto++ KDF Options)

  • Description: The application uses a weak key derivation function (KDF) provided by Crypto++, such as a low-iteration PBKDF2 or a simple hash-based KDF. An attacker can perform brute-force or dictionary attacks on the password to derive the encryption key. This is a direct misuse of Crypto++'s KDF options.
    • Impact:
      • Key compromise: Obtain the encryption key.
      • Loss of confidentiality and integrity.
    • Affected Crypto++ Component:
      • PKCS5_PBKDF2_HMAC (if used with low iteration count)
      • PasswordBasedKeyDerivationFunction (base class, if a weak derived class is used)
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Use Strong KDFs: Use Argon2 (Argon2id). If PBKDF2 must be used, use a very high iteration count (hundreds of thousands or more).
      • Salting: Use a unique, random salt (at least 128 bits).
      • Consider Alternatives: Use a dedicated key management library or HSM.

Threat: Random Number Generator Weakness (Misusing Crypto++ RNG)

  • Description: The application relies on a weak or improperly configured random number generator (RNG) within Crypto++. This could involve using a non-cryptographic PRNG or failing to properly seed AutoSeededRandomPool. An attacker could predict generated random numbers, compromising key generation, IVs, and nonces.
    • Impact:
      • Key Compromise: Predictable keys.
      • Replay Attacks: Predictable nonces.
      • Loss of confidentiality and integrity.
    • Affected Crypto++ Component:
      • RandomNumberGenerator (base class)
      • AutoSeededRandomPool (if improperly seeded)
      • OS_GenerateRandomBlock (if the OS RNG is weak or unavailable)
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Use a Strong RNG: Ensure Crypto++ uses a CSPRNG. AutoSeededRandomPool is usually good, but verify proper seeding.
      • OS-Provided RNG: Prefer the OS's CSPRNG via OS_GenerateRandomBlock.
      • External Entropy: Seed with additional entropy from a trusted source.
      • Avoid Weak RNGs: Never use std::rand() or Mersenne Twister for cryptography.

Threat: Incorrect use of SecByteBlock (Leading to Memory Issues)

  • Description: SecByteBlock is misused, leading to vulnerabilities. Examples include accessing the underlying data pointer without bounds checking or failing to zeroize memory after use. This is a direct misuse of a core Crypto++ memory management class.
    • Impact:
      • Information Leakage: Sensitive data remains in memory.
      • Buffer Overflows: Incorrect pointer arithmetic.
    • Affected Crypto++ Component:
      • SecByteBlock
    • Risk Severity: High
    • Mitigation Strategies:
      • Use SecByteBlock API: Always use provided API methods. Avoid direct pointer manipulation.
      • Zeroize Memory: Ensure memory is zeroized when no longer needed. SecByteBlock's destructor should handle this, but explicit zeroization is good practice. Use memset_s or Crypto++'s সেক্রেtZeroize.
      • Code Review: Review code using SecByteBlock.

Threat: Unvalidated Signature Verification (Using Crypto++ Incorrectly)

  • Description: The application uses Crypto++ for digital signature verification but fails to properly validate the signature or the certificate chain (if applicable). This is a direct misuse of Crypto++'s signature verification APIs. An attacker could forge a signature or use an invalid certificate.
    • Impact:
      • Integrity Violation: Accept modified or forged data.
      • Loss of Trust.
    • Affected Crypto++ Component:
      • Signature verification functions (e.g., RSASS<>::Verifier, ECDSA<>::Verifier, DSA::Verifier)
      • Hash functions used in signature schemes (e.g., SHA256, SHA3_256)
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Complete Verification: Implement full verification:
        • Check signature against the public key.
        • Validate the certificate chain (if applicable).
        • Check for certificate revocation.
      • Strong Algorithms: Use strong signature algorithms.
      • Code Review: Thoroughly review verification code.