Use of a weak cryptographic initialization vector

ID

kotlin.weak_encryption_initialization_vector

Severity

critical

Resource

Cryptography

Language

Kotlin

Tags

CWE:1204, NIST.SP.800-53, OWASP:2021:A2, PCI-DSS:6.5.3, crypto

Description

The improper use of initialization vectors (IVs) in encryption can weaken data security by enabling pattern detection and making the ciphertext vulnerable to attacks. It’s critical to ensure the IV is generated securely and used correctly to maintain encryption strength.

Rationale

Initialization vectors (IVs) are crucial in encryption schemes like CBC or GCM to ensure the same plaintext results in different ciphertexts. A weak or improperly used IV, such as a static or predictable one, can allow attackers to uncover patterns in the data, leading to potential data leaks or unauthorized access.

Consider the following Kotlin code:

import javax.crypto.Cipher
import javax.crypto.SecretKey
import javax.crypto.spec.GCMParameterSpec

fun encrypt(data: ByteArray, key: SecretKey): ByteArray {
    // Use a secure random IV for better security
    val iv = ByteArray(16) { 0.toByte() }
    val params = GCMParameterSpec(128, iv) // FLAW

    val cipher = Cipher.getInstance("AES/GCM/NoPadding") // Correct padding for GCM
    cipher.init(Cipher.ENCRYPT_MODE, key, params)

    return cipher.doFinal(data)
}

Remediation

To remediate issues with weak or improperly used IVs, ensure they are generated securely and uniquely for each encryption operation.

The remediation example for Kotlin would look like this:

import javax.crypto.Cipher
import javax.crypto.SecretKey
import javax.crypto.spec.GCMParameterSpec
import java.security.SecureRandom

fun encrypt(data: ByteArray, key: SecretKey): ByteArray {
    // Generate a secure random initialization vector (IV)
    val iv = ByteArray(16)
    val random = SecureRandom.getInstanceStrong()
    random.nextBytes(iv) // GOOD: random initialization vector

    val params = GCMParameterSpec(128, iv)
    val cipher = Cipher.getInstance("AES/GCM/NoPadding") // Correct padding for GCM
    cipher.init(Cipher.ENCRYPT_MODE, key, params)

    return cipher.doFinal(data)
}

References

  • CWE-1204 : Generation of Weak Initialization Vector (IV).