CWE-328 Weak Hash Algorithm (MD5/SHA1)

Description

Weak Hash Algorithm (MD5/SHA1)

Reference: https://cwe.mitre.org/data/definitions/328.html

OWASP Category: A02:2021 – Cryptographic Failures

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Vulnerable Pattern

❌ Example 1: Vulnerable Pattern

// VULNERABLE: Using weak hash algorithms
MessageDigest md = MessageDigest.getInstance("MD5");  // Collision attacks!
byte[] hash = md.digest(data.getBytes());

// VULNERABLE: SHA1 for password hashing
MessageDigest sha1 = MessageDigest.getInstance("SHA1");  // Weak!
String hashedPassword = Base64.getEncoder().encodeToString(sha1.digest(password.getBytes()));

Why it's vulnerable: This pattern is vulnerable to Weak Hash Algorithm (MD5/SHA1)

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Deterministic Fix

✅ Secure Implementation: Secure Implementation

// SECURE: Use SHA-256 for integrity checks
MessageDigest md = MessageDigest.getInstance("SHA-256");
byte[] hash = md.digest(data.getBytes(StandardCharsets.UTF_8));

// SECURE: For passwords, use bcrypt/scrypt/argon2
// Option 1: BCrypt (Spring Security)
BCryptPasswordEncoder encoder = new BCryptPasswordEncoder(12);
String hashedPassword = encoder.encode(password);
boolean matches = encoder.matches(password, hashedPassword);

// Option 2: Argon2 (stronger, newer)
Argon2PasswordEncoder encoder = new Argon2PasswordEncoder(16, 32, 1, 65536, 3);
String hashedPassword = encoder.encode(password);

Why it's secure: Implements proper protection against Weak Hash Algorithm (MD5/SHA1)

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Detection Pattern

Look for these patterns in your codebase:

# Find MD5/SHA1 usage
grep -rn "getInstance.*MD5\\|getInstance.*SHA1\\|getInstance.*SHA-1" --include="*.java"

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Remediation Steps

1. Replace MD5/SHA1 with SHA-256 or SHA-512

2. For passwords, use BCrypt, SCrypt, or Argon2

3. Never use fast hashes (MD5/SHA) for passwords

4. Use HMAC-SHA256 for message authentication

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Key Imports

import java.security.MessageDigest;

import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;

import org.springframework.security.crypto.argon2.Argon2PasswordEncoder;

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Verification

After remediation:

• Run SAST scanner to confirm vulnerability is resolved

• Review all instances of the vulnerable pattern

• Add unit tests that verify the secure implementation

• Check for similar patterns in related code

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Trigger Examples

Fix CWE-328 vulnerability
Resolve Weak Hash Algorithm (MD5/SHA1) issue
Secure this Java code against weak hash algorithm (md5/sha1)
SAST reports CWE-328

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Common Vulnerable Locations

Layer	Files	Patterns

| Controller | *Controller.java | User input handling |

| Service | *Service.java | Business logic |

| Repository | *Repository.java | Data access |

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References

• CWE-328: Weak Hash

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Source: Generated by Java CWE Security Skills Generator Last Updated: 2026-03-07