Cryptographic Failures

# Cryptographic Failures (OWASP A02)

## Purpose

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

## OWASP Top 10 Mapping

**Category**: A02 - 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

```bash
# 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

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

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

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

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

#### Java

```bash
# 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

```bash
# 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

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

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

#### TypeScript

```bash
# 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

```bash
# 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

```bash
# 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

```bash
# 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

```bash
# 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

```bash
# 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

```bash
# 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

```bash
# 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

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

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

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

### Encryption

```python
# 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
# 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 |