Cryptographic Failures - Hunter Knowledge Base

Broken or misused cryptography: weak algorithms, predictable randomness, static keys/IVs, missing integrity, or protecting nothing (plaintext). Impact depends on what the crypto was meant to protect.

What to hunt

• Weak/broken algorithms (CWE-327/328): MD5/SHA1 for passwords or signatures, DES/3DES/RC4, fast hashes for password storage (should be argon2/bcrypt/scrypt/PBKDF2).
• Insecure randomness (CWE-330/338): Math.random(), random.random()/random.randint, rand(), java.util.Random, time-seeded RNG used for tokens/session ids/password-reset/OTP/nonces/keys.
• Static/hardcoded key or IV (CWE-321/329): fixed AES key/IV in source; reused nonce; predictable salt.
• ECB mode (CWE-327): AES/ECB leaks plaintext patterns.
• Missing integrity / unauthenticated encryption: CBC without a MAC (padding-oracle risk); encrypt without authenticate; not using AEAD (AES-GCM/ChaCha20-Poly1305).
• Bad TLS/cert handling: disabled verification (verify=False, rejectUnauthorized:false, InsecureSkipVerify:true, trust-all TrustManager/HostnameVerifier).
• Weak KDF params: low PBKDF2 iterations, no salt.

Sinks (grep targets)

md5(|sha1(|MD5|SHA1|DES|RC4|Math.random|random\.(random|randint|choice)|util.Random|AES/ECB|ECB| verify=False|rejectUnauthorized|InsecureSkipVerify|createCipher\(|PBKDF2.*iterations|IV\s*=. Look near "password", "token", "key", "encrypt", "sign", "session".

Detection recipe

1. Grep the patterns above; for each, determine what is being protected and the threat model.
2. Password storage: which hash + salt + params? Token generation: which RNG? Encryption: algorithm, mode, key/IV source, integrity?
3. Confirm the weakness is used on security-relevant data (a non-security CRC/md5 for a cache key is fine).

PoC / evidence

• The code using the weak primitive at file:line. For randomness: show tokens derive from a predictable RNG (attacker can predict/brute future values). For static key: show the literal key/IV.
• Padding oracle / ECB: describe the exploit conditions; a full oracle PoC is usually needs-runtime.

False-positive filters

• MD5/SHA1 used for non-security purposes (ETags, cache keys, dedup checksums) - not a finding.
• CSPRNG in use: secrets/os.urandom (Python), crypto.randomBytes (Node), SecureRandom (Java), crypto/rand (Go). Password hashing via argon2/bcrypt/scrypt with salt.
• AEAD (AES-GCM/ChaCha20-Poly1305) or encrypt-then-MAC; per-message random IV/nonce; keys from a KMS/secret manager. TLS verification enabled (the insecure flags are dev-only and not shipped).

CWE / OWASP / severity

CWE-327/328/330/338/321/326/916, CWE-295 (cert validation). OWASP A02:2021. Forgeable tokens / broken auth crypto / disabled TLS verification -> high/critical; weak-but-limited -> medium.

Chaining hints

Predictable reset/session tokens -> auth account takeover; static JWT/HMAC key -> forge tokens; disabled TLS verification -> MITM -> credential capture; weak password hash + a secrets/sqli DB dump -> mass credential cracking.

Mitigation

Use argon2/bcrypt/scrypt (salted) for passwords; CSPRNG for all tokens/keys/IVs; AES-GCM or ChaCha20-Poly1305 (AEAD) with per-message nonces; keys from a KMS/secret manager, never hardcoded; enforce TLS certificate verification; drop MD5/SHA1/DES/RC4/ECB for security purposes.