Offensive Crypto Attacks
Systematic methodology for identifying and exploiting cryptographic implementation...
Install
npx skills add SnailSploit/Claude-Red --skill offensive-crypto-attacks -g -a claude-code -y- Repository
- SnailSploit/Claude-Red10.2k
- Category
- Security
- Updated
- 23d ago
- License
- MIT
- Context cost
- Mediumabout 3,000 tokens
- Runs scripts
- No, instructions only
What it does
Systematic methodology for identifying and exploiting cryptographic implementation weaknesses in real-world applications. Covers padding oracle attacks against CBC-mode ciphers with PKCS7 padding (Vaudenay's original attack through modern padbuster automation), ECB mode exploitation including block cut-and-paste and byte-at-a-time decryption, hash length extension attacks against SHA1/SHA256/MD5-based MACs using HashPump, RSA vulnerabilities including small public exponent, common modulus, Bleichenbacher PKCS1v1.5 padding oracle, and Coppersmith's method for partial key recovery. Addresses weak PRNG exploitation targeting time-seeded generators and Mersenne Twister MT19937 state recovery from observed outputs, timing side-channel attacks against comparison operations, nonce reuse in AES-GCM leading to authentication key recovery, and key derivation weaknesses including insufficient iteration counts and missing salts. Primary tooling includes padbuster, RsaCtfTool, hashpump, and PyCryptodome for building custom exploit payloads. Maps to CWE-327 (Use of a Broken or Risky Cryptographic Algorithm), CWE-328 (Use of Weak Hash), and CWE-330 (Use of Insufficiently Random Values). Emphasizes black-box identification of vulnerable implementations before transitioning to targeted exploitation.
Cryptographic Implementation Attacks
You are performing offensive cryptographic analysis against target applications. This skill covers the identification and exploitation of flawed cryptographic implementations -- not breaks against the underlying mathematical primitives, but against the ways developers misuse them. You treat every encrypted blob, signed token, and hashed value as a potential attack surface.
Quick Workflow
- Identify cryptographic touchpoints -- cookies, tokens, API parameters, stored credentials, signed URLs.
- Fingerprint the algorithm and mode -- measure ciphertext length behavior, detect block alignment, check for Base64/hex encoding layers.
- Classify the vulnerability class -- padding oracle, ECB determinism, weak MAC construction, RSA parameter weakness, PRNG predictability.
- Select and configure the appropriate tool or custom script.
- Execute the attack, decrypt or forge the target value.
- Document the cryptographic weakness, its root cause, and the remediation path.
Padding Oracle Attacks
Padding oracle attacks exploit systems that reveal whether CBC-mode decrypted plaintext has valid PKCS7 padding. A single bit of information -- valid or invalid padding -- is sufficient to decrypt any ciphertext block or forge arbitrary plaintext without knowing the key.
Identify the oracle by submitting modified ciphertext and observing differential responses. The oracle can manifest as distinct HTTP status codes, different error messages, timing differences, or behavioral changes in application logic.
Use padbuster for automated exploitation against web applications:
# Decrypt an encrypted cookie value
# URL is the endpoint, EncryptedValue is the target, BlockSize is typically 8 or 16
padbuster http://target.com/app?token=EncryptedValue EncryptedValue 16 \
-cookies "session=EncryptedValue" \
-encoding 0 \
-error "invalid"
