Cryptographic Failures (OWASP A04)

Purpose

Provide detection patterns for cryptographic vulnerabilities including weak algorithms, hardcoded secrets, insufficient key lengths, and insecure random number generation.

OWASP 2025 Mapping

Category: A04 - Cryptographic Failures

CWEs:

• CWE-326: Inadequate Encryption Strength
• CWE-327: Use of Broken or Risky Crypto Algorithm
• CWE-328: Reversible One-Way Hash
• CWE-330: Use of Insufficiently Random Values
• CWE-338: Use of Cryptographically Weak PRNG
• CWE-798: Use of Hardcoded Credentials

When to Use

Activate this skill when:

• Reviewing password hashing implementations
• Checking encryption algorithm usage
• Looking for hardcoded secrets/API keys
• Auditing random number generation
• Verifying key management practices

---

Weak Hash Algorithms

Detection Patterns

# MD5 usage (broken for security)
grep -rniE "md5\(|MD5\.|hashlib\.md5|MessageDigest.*MD5|crypto\.MD5" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# SHA1 usage (deprecated for security)
grep -rniE "sha1\(|SHA1\.|hashlib\.sha1|MessageDigest.*SHA-1|crypto\.SHA1" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Password hashing with weak algorithms
grep -rniE "password.*md5|password.*sha1|hash.*password.*md5" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

Language-Specific Patterns

Python

# Weak hashing
grep -rniE "hashlib\.md5|hashlib\.sha1" --include="*.py"

# Should use: bcrypt, argon2, scrypt
grep -rniE "bcrypt|argon2|scrypt" --include="*.py"

Vulnerable:

# VULNERABLE: MD5 for passwords
password_hash = hashlib.md5(password.encode()).hexdigest()

Secure:

# SAFE: bcrypt for passwords
password_hash = bcrypt.hashpw(password.encode(), bcrypt.gensalt())

Java

# Weak MessageDigest
grep -rniE "MessageDigest\.getInstance.*MD5|MessageDigest\.getInstance.*SHA-1" --include="*.java"

# Should use: BCrypt, Argon2, PBKDF2
grep -rniE "BCrypt|Argon2|PBKDF2|SecretKeyFactory" --include="*.java"

Go

# Weak crypto imports
grep -rniE "crypto/md5|crypto/sha1" --include="*.go"

# Should use: bcrypt, argon2
grep -rniE "golang\.org/x/crypto/bcrypt|golang\.org/x/crypto/argon2" --include="*.go"

PHP

# Weak hashing
grep -rniE "md5\(|sha1\(" --include="*.php"

# Should use: password_hash
grep -rniE "password_hash|PASSWORD_BCRYPT|PASSWORD_ARGON2" --include="*.php"

TypeScript

# Weak crypto
grep -rniE "createHash.*md5|createHash.*sha1" --include="*.ts"

# Should use: bcrypt
grep -rniE "bcrypt\.hash|argon2" --include="*.ts"

---

Weak Encryption Algorithms

Detection Patterns

# DES (broken)
grep -rniE "DES|DESede|TripleDES" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# RC4 (broken)
grep -rniE "RC4|ARC4|ARCFOUR" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# ECB mode (insecure)
grep -rniE "ECB|AES/ECB|MODE_ECB" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Blowfish (deprecated)
grep -rniE "Blowfish|BLOWFISH" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

Secure Alternatives

Weak	Secure Alternative
DES	AES-256
3DES	AES-256
RC4	ChaCha20 or AES-GCM
ECB mode	GCM or CBC with HMAC
Blowfish	AES-256
RSA-1024	RSA-2048+ or ECDSA

---

Hardcoded Secrets

Detection Patterns

# API keys
grep -rniE "api[_-]?key\s*[=:]\s*['\"][a-zA-Z0-9]{16,}['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Passwords
grep -rniE "password\s*[=:]\s*['\"][^'\"]+['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Secret keys
grep -rniE "secret[_-]?key\s*[=:]\s*['\"][^'\"]+['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# AWS credentials
grep -rniE "AKIA[0-9A-Z]{16}|aws_secret_access_key" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php" --include="*.env"

# Private keys
grep -rniE "BEGIN RSA PRIVATE KEY|BEGIN PRIVATE KEY|BEGIN EC PRIVATE KEY" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php" --include="*.pem"

# JWT secrets
grep -rniE "jwt[_-]?secret\s*[=:]\s*['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

High-Entropy String Detection

# Long alphanumeric strings (potential secrets)
grep -rniE "['\"][a-zA-Z0-9+/=]{32,}['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

---

Insecure Random Number Generation

Detection Patterns

# JavaScript/TypeScript - Math.random (NOT cryptographically secure)
grep -rniE "Math\.random\(\)" --include="*.ts" --include="*.js"

# Python - random module (NOT cryptographically secure)
grep -rniE "import random|from random|random\.random|random\.randint" --include="*.py"

# Java - java.util.Random (NOT cryptographically secure)
grep -rniE "new Random\(\)|java\.util\.Random" --include="*.java"

# PHP - rand/mt_rand (NOT cryptographically secure)
grep -rniE "rand\(|mt_rand\(" --include="*.php"

# Go - math/rand (NOT cryptographically secure)
grep -rniE "math/rand|rand\.Intn|rand\.Int\(" --include="*.go"

Secure Alternatives

Language	Insecure	Secure
Python	random.random()	secrets.token_bytes()
Java	java.util.Random	java.security.SecureRandom
Go	math/rand	crypto/rand
JavaScript	Math.random()	crypto.randomBytes()
PHP	rand(), mt_rand()	random_bytes(), random_int()

---

Insufficient Key Length

Detection Patterns

# RSA key size (should be 2048+)
grep -rniE "RSA.*1024|keysize.*1024|KeyPairGenerator.*1024" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# AES key size (should be 256 for sensitive data)
grep -rniE "AES.*128|aes-128" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# HMAC key size
grep -rniE "hmac.*key.*['\"][a-zA-Z0-9]{1,15}['\"]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

Minimum Key Lengths

Algorithm	Minimum	Recommended
RSA	2048 bits	4096 bits
AES	128 bits	256 bits
ECDSA	256 bits	384 bits
HMAC	256 bits	512 bits

---

Predictable IVs/Nonces

Detection Patterns

# Static/zero IV
grep -rniE "iv\s*=\s*['\"]0{16,}['\"]|iv\s*=\s*bytes\(16\)|iv.*\[0,0,0" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Reused nonce
grep -rniE "nonce\s*=\s*['\"]|static.*nonce|const.*nonce" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

---

Missing Encryption

Detection Patterns

# Plaintext password storage
grep -rniE "password\s*=\s*request|user\.password\s*=\s*" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# HTTP instead of HTTPS
grep -rniE "http://[^localhost]|http://[^127\.0\.0\.1]" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php"

# Unencrypted database connection
grep -rniE "sslmode=disable|useSSL=false|ssl=false" --include="*.go" --include="*.py" --include="*.java" --include="*.ts" --include="*.php" --include="*.env"

---

Broken Certificate Validation

Detection Patterns

# Go - Skip TLS verification
grep -rniE "InsecureSkipVerify\s*:\s*true" --include="*.go"

# Python - Disable SSL verification
grep -rniE "verify\s*=\s*False|CERT_NONE" --include="*.py"

# Java - Trust all certificates
grep -rniE "TrustAllCerts|X509TrustManager|checkServerTrusted.*return" --include="*.java"

# Node.js - Reject unauthorized false
grep -rniE "rejectUnauthorized\s*:\s*false|NODE_TLS_REJECT_UNAUTHORIZED" --include="*.ts" --include="*.js"

# PHP - Disable SSL verification
grep -rniE "CURLOPT_SSL_VERIFYPEER\s*=>\s*false|verify_peer.*false" --include="*.php"

---

Secure Patterns

Password Hashing

# Python - Argon2 (recommended)
from argon2 import PasswordHasher
ph = PasswordHasher()
hash = ph.hash(password)

// Java - BCrypt
String hash = BCrypt.hashpw(password, BCrypt.gensalt(12));

// Go - bcrypt
hash, _ := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)

Encryption

# Python - AES-GCM
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
key = AESGCM.generate_key(bit_length=256)
aesgcm = AESGCM(key)
nonce = os.urandom(12)  # Random nonce
ciphertext = aesgcm.encrypt(nonce, plaintext, None)

Random Generation

# Python - Secure random
import secrets
token = secrets.token_hex(32)

---

Verification Checklist

• No MD5/SHA1 for password hashing
• No DES/RC4/ECB encryption
• No hardcoded secrets
• Cryptographically secure RNG used
• Key lengths meet minimums
• Random IVs/nonces
• TLS 1.2+ with valid certificates
• Secrets from environment/vault

---

CWE References

CWE	Name	Example
CWE-326	Inadequate Encryption	RSA-1024
CWE-327	Broken Crypto	MD5, DES, RC4
CWE-328	Reversible Hash	MD5 for passwords
CWE-330	Insufficient Randomness	Math.random for tokens
CWE-338	Weak PRNG	rand() for crypto
CWE-798	Hardcoded Credentials	API keys in code