# Cwe 328 Weak Hash Algorithm

> Use this skill when you need to remediate CWE-328 (Weak Hash Algorithm (MD5/SHA1)) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing weak hash algorithm (md5/sha1) issues.

- Skill: `developerscoffee/cwe-328-weak-hash-algorithm` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-328-weak-hash-algorithm`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-328-weak-hash-algorithm/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- License: MIT
- Author: DevelopersCoffee (https://skillmd.com/u/developerscoffee)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/developerscoffee/cwe-328-weak-hash-algorithm

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# 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


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// 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)




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// 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)




---

## Detection Pattern

Look for these patterns in your codebase:


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



---

## 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


---

## Key Imports

```java

import java.security.MessageDigest;

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

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

```

---

## 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


---

## 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
```

---

## Common Vulnerable Locations

| Layer | Files | Patterns |
|-------|-------|----------|

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

| Service | `*Service.java` | Business logic |

| Repository | `*Repository.java` | Data access |


---

## References


- [CWE-328: Weak Hash](https://cwe.mitre.org/data/definitions/328.html)


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**Source**: Generated by [Java CWE Security Skills Generator](https://github.com/DevelopersCoffee/java-cwe-security-skills)
**Last Updated**: 2026-03-07