java.lang.security.audit.crypto.no-static-initialization-vector.no-static-initialization-vector

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Initialization Vectors (IVs) for block ciphers should be randomly generated each time they are used. Using a static IV means the same plaintext encrypts to the same ciphertext every time, weakening the strength of the encryption.

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Defintion

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rules:
  - id: no-static-initialization-vector
    message: Initialization Vectors (IVs) for block ciphers should be randomly
      generated each time they are used. Using a static IV means the same
      plaintext encrypts to the same ciphertext every time, weakening the
      strength of the encryption.
    metadata:
      cwe:
        - "CWE-329: Generation of Predictable IV with CBC Mode"
      owasp:
        - A02:2021 - Cryptographic Failures
      source-rule-url: https://find-sec-bugs.github.io/bugs.htm#STATIC_IV
      asvs:
        section: V6 Stored Cryptography Verification Requirements
        control_id: 6.2.5 Insecure Algorithm
        control_url: https://github.com/OWASP/ASVS/blob/master/4.0/en/0x14-V6-Cryptography.md#v62-algorithms
        version: "4"
      references:
        - https://cwe.mitre.org/data/definitions/329.html
      category: security
      technology:
        - java
      subcategory:
        - vuln
      likelihood: MEDIUM
      impact: MEDIUM
      confidence: HIGH
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    severity: WARNING
    languages:
      - java
    pattern-either:
      - pattern: |
          byte[] $IV = {
              ...
          };
          ...
          new IvParameterSpec($IV, ...);
      - pattern: |
          class $CLASS {
              byte[] $IV = {
                  ...
              };
              ...
              $METHOD(...) {
                  ...
                  new IvParameterSpec($IV, ...);
                  ...
              }
          }

Examples

no-static-initialization-vector.java

public class StaticIV {

    public StaticIV() {
        // ruleid: no-static-initialization-vector
        byte[] iv = {
            (byte) 0, (byte) 0, (byte) 0, (byte) 0,
            (byte) 0, (byte) 0, (byte) 0, (byte) 0,
            (byte) 0, (byte) 0, (byte) 0, (byte) 0,
            (byte) 0, (byte) 0, (byte) 0, (byte) 0
        };

        IvParameterSpec staticIvSpec = new IvParameterSpec(iv);

        c.init(Cipher.ENCRYPT_MODE, skeySpec, staticIvSpec, new SecureRandom());
    }
}

// ruleid: no-static-initialization-vector
public class StaticIV2 {
    byte[] iv = {
        (byte) 0, (byte) 0, (byte) 0, (byte) 0,
        (byte) 0, (byte) 0, (byte) 0, (byte) 0,
        (byte) 0, (byte) 0, (byte) 0, (byte) 0,
        (byte) 0, (byte) 0, (byte) 0, (byte) 0
    };


    public StaticIV2() {
        IvParameterSpec staticIvSpec = new IvParameterSpec(iv);

        c.init(Cipher.ENCRYPT_MODE, skeySpec, staticIvSpec, new SecureRandom());
    }
}

public class RandomIV {

    public RandomIV() {
        // ok: no-static-initialization-vector
        byte[] iv = new byte[16];
        new SecureRandom().nextBytes(iv);

        IvParameterSpec staticIvSpec = new IvParameterSpec(iv); // IvParameterSpec initialized using its own randomizer.

        c.init(Cipher.ENCRYPT_MODE, skeySpec, staticIvSpec, new SecureRandom());
    }
}