cwe-327-weak-cryptography

name	cwe-327-weak-cryptography
description	Use this skill when you need to remediate CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing use of a broken or risky cryptographic algorithm issues.
version	1.0.0
license	MIT
tags	["security","java","cwe-327","remediation","sast","cryptography","weak-crypto"]

CWE-327 Use of a Broken or Risky Cryptographic Algorithm

Description

Use of a Broken or Risky Cryptographic Algorithm

Reference: https://cwe.mitre.org/data/definitions/327.html

OWASP Category: A02:2021 – Cryptographic Failures

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Vulnerable Pattern

❌ Example 1

    private static final String LEVEL4_SECRET = "s3cretKey";
    private static final String LEVEL4_ENCODED =
            java.util.Base64.getEncoder().encodeToString(LEVEL4_SECRET.getBytes());

    private static final String LEVEL5_SECRET = "strongPass!";
    private static final String LEVEL5_SALT = "randomSalt123";
    private static final String LEVEL5_HASH;

    static {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            digest.update(LEVEL5_SALT.getBytes());
            byte[] hash = digest.digest(LEVEL5_SECRET.getBytes());
            LEVEL5_HASH = bytesToHex(hash);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("SHA-256 not available", e);
        }
    }

❌ Example 2

    public ResponseEntity<GenericVulnerabilityResponseBean<String>> getVulnerablePayloadLevel1(
            @RequestParam Map<String, String> queryParams) {
        String password = queryParams.get(PASSWORD_PARAM);

        // No password param: return the challenge hash
        if (password == null || password.isEmpty()) {
            return new ResponseEntity<>(
                    new GenericVulnerabilityResponseBean<>(
                            "CHALLENGE: A user's password is stored as MD5 hash: "
                                    + LEVEL1_HASH
                                    + " — Crack it and enter the original password!",
                            false),
                    HttpStatus.OK);
        }

        // Verify the guess
        String guessHash = DigestUtils.md5Hex(password);
        if (guessHash.equals(LEVEL1_HASH)) {
        // ... (truncated for brevity)

---

Deterministic Fix

✅ Secure Implementation

    public ResponseEntity<GenericVulnerabilityResponseBean<String>> getVulnerablePayloadLevel4(
            @RequestParam Map<String, String> queryParams) {
        String password = queryParams.get(PASSWORD_PARAM);

        if (password == null || password.isEmpty()) {
            return new ResponseEntity<>(
                    new GenericVulnerabilityResponseBean<>(
                            "CHALLENGE: The system 'encrypts' passwords using Base64 encoding. "
                                    + "The stored password is: "
                                    + LEVEL4_ENCODED
                                    + " — Decode it and enter the original password!",
                            false),
                    HttpStatus.OK);
        }

        if (password.equals(LEVEL4_SECRET)) {
            return new ResponseEntity<>(
                    new GenericVulnerabilityResponseBean<>(
                            "Correct! The password was '"
                                    + LEVEL4_SECRET
                                    + "'. Base64 is an encoding, NOT encryption."
                                    + " It provides zero security — anyone can decode it instantly.",
                            true),
                    HttpStatus.OK);
        } else {
        // ... (truncated for brevity)

✅ Secure Implementation

    public ResponseEntity<GenericVulnerabilityResponseBean<String>> getVulnerablePayloadLevel4(
            @RequestParam Map<String, String> queryParams) {
        String password = queryParams.get(PASSWORD_PARAM);

        if (password == null || password.isEmpty()) {
            return new ResponseEntity<>(
                    new GenericVulnerabilityResponseBean<>(
                            "CHALLENGE: The system 'encrypts' passwords using Base64 encoding. "
                                    + "The stored password is: "
                                    + LEVEL4_ENCODED
                                    + " — Decode it and enter the original password!",
                            false),
                    HttpStatus.OK);
        }

        if (password.equals(LEVEL4_SECRET)) {
            return new ResponseEntity<>(
                    new GenericVulnerabilityResponseBean<>(
                            "Correct! The password was '"
                                    + LEVEL4_SECRET
                                    + "'. Base64 is an encoding, NOT encryption."
                                    + " It provides zero security — anyone can decode it instantly.",
                            true),
                    HttpStatus.OK);
        } else {
        // ... (truncated for brevity)

---

Detection Pattern

Look for these patterns in your codebase:

# Find weak hash algorithms
grep -rn "MD5\|SHA-1\|SHA1" --include="*.java"

# Find weak ciphers
grep -rn "DES\|RC4\|ECB" --include="*.java"

---

Remediation Steps

1. Replace MD5/SHA1 with SHA-256 or SHA-3 for hashing

2. Use bcrypt, scrypt, or Argon2 for password hashing

3. Replace DES/3DES with AES-256

4. Use GCM or CBC mode with proper IV instead of ECB

5. Use secure random for key generation

---

Key Imports

import javax.crypto.Cipher;

import java.security.MessageDigest;

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

---

Verification

After remediation:

• Re-run SAST scan - CWE-327 should be resolved

• Verify strong algorithms are used (AES-256, SHA-256)

• Check key lengths meet minimum requirements

---

Trigger Examples

Fix CWE-327 vulnerability
Resolve Use of a Broken or Risky Cryptographic Algorithm issue
Secure this Java code against use of a broken or risky cryptographic algorithm
SAST reports CWE-327

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Common Vulnerable Locations

Layer	Files	Patterns

| Security | *Security*.java | Password handling |

| Utility | *Crypto*.java, *Hash*.java | Encryption/hashing |

| Service | *Service.java | Data encryption |

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References

• CWE-327: Broken Crypto

• OWASP Cryptographic Failures

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