csharp.dotnet.security.use_ecb_mode.use_ecb_mode

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Usage of the insecure ECB mode detected. You should use an authenticated encryption mode instead, which is implemented by the classes AesGcm or ChaCha20Poly1305.

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Defintion

rules:
  - id: use_ecb_mode
    message: Usage of the insecure ECB mode detected. You should use an
      authenticated encryption mode instead, which is implemented by the classes
      AesGcm or ChaCha20Poly1305.
    severity: WARNING
    metadata:
      likelihood: HIGH
      impact: MEDIUM
      confidence: HIGH
      category: security
      cwe:
        - "CWE-327: Use of a Broken or Risky Cryptographic Algorithm"
      owasp:
        - A02:2021 - Cryptographic Failures
      references:
        - https://learn.microsoft.com/en-gb/dotnet/api/system.security.cryptography.chacha20poly1305?view=net-6.0
        - https://learn.microsoft.com/en-gb/dotnet/api/system.security.cryptography.aesgcm?view=net-6.0
        - https://learn.microsoft.com/en-gb/dotnet/api/system.security.cryptography.ciphermode?view=net-6.0
        - https://cheatsheetseries.owasp.org/cheatsheets/Cryptographic_Storage_Cheat_Sheet.html#cipher-modes
      subcategory:
        - vuln
      technology:
        - .net
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    languages:
      - csharp
    patterns:
      - pattern-either:
          - pattern: ($KEYTYPE $KEY).EncryptEcb(...);
          - pattern: ($KEYTYPE $KEY).DecryptEcb(...);
          - pattern: ($KEYTYPE $KEY).Mode = CipherMode.ECB;
      - metavariable-pattern:
          metavariable: $KEYTYPE
          pattern-either:
            - pattern: SymmetricAlgorithm
            - pattern: Aes
            - pattern: Rijndael
            - pattern: DES
            - pattern: TripleDES
            - pattern: RC2

Examples

use_ecb_mode.cs

using System;
using System.Security.Cryptography;
					
public class Encryption
{
	public void EncryptWithAesEcb() {
		Aes key = Aes.Create();
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var encryptor = key.CreateEncryptor();
		byte[] msg = new byte[32];
		var cipherText = encryptor.TransformFinalBlock(msg, 0, msg.Length);
	}
	
	public void EncryptWithAesEcb2() {
		Aes key = Aes.Create();
		byte[] msg = new byte[32];
		//ruleid: use_ecb_mode
		var cipherText = key.EncryptEcb(msg, PaddingMode.PKCS7);
	}
	
	public void DecryptWithAesEcb(byte[] cipherText) {
		Aes key = Aes.Create();
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var decryptor = key.CreateDecryptor();
		var msg = decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);
	}
	
	public void DecryptWithAesEcb2(byte[] cipherText) {
		Aes key = Aes.Create();
		//ruleid: use_ecb_mode
		var msgText = key.DecryptEcb(cipherText, PaddingMode.PKCS7);
	}
	
	public void EncryptWith3DESEcb() {
		TripleDES key = TripleDES.Create();
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var encryptor = key.CreateEncryptor();
		byte[] msg = new byte[32];
		var cipherText = encryptor.TransformFinalBlock(msg, 0, msg.Length);
	}
	
	public void EncryptWith3DESEcb2() {
		TripleDES key = TripleDES.Create();
		byte[] msg = new byte[32];
		//ruleid: use_ecb_mode
		var cipherText = key.EncryptEcb(msg, PaddingMode.PKCS7);
	}
	
	public void DecryptWith3DESEcb(byte[] cipherText) {
		TripleDES key = TripleDES.Create();
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var decryptor = key.CreateDecryptor();
		var msg = decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);
	}
	
	public void DecryptWith3DESEcb2(byte[] cipherText) {
		TripleDES key = TripleDES.Create();
		//ruleid: use_ecb_mode
		var msgText = key.DecryptEcb(cipherText, PaddingMode.PKCS7);
	}
	
	public void EncryptWithEcb(SymmetricAlgorithm key) {
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var encryptor = key.CreateEncryptor();
		byte[] msg = new byte[32];
		var cipherText = encryptor.TransformFinalBlock(msg, 0, msg.Length);
	}
	
	public void EncryptWithEcb2(SymmetricAlgorithm key) {
		byte[] msg = new byte[32];
		//ruleid: use_ecb_mode
		var cipherText = key.EncryptEcb(msg, PaddingMode.PKCS7);
	}
	
	public void DecryptWithEcb(SymmetricAlgorithm key, byte[] cipherText) {
		//ruleid: use_ecb_mode
		key.Mode = CipherMode.ECB;
		using var decryptor = key.CreateDecryptor();
		var msg = decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);
	}
	
	public void DecryptWithEcb2(SymmetricAlgorithm key, byte[] cipherText) {
		//ruleid: use_ecb_mode
		var msgText = key.DecryptEcb(cipherText, PaddingMode.PKCS7);
	}
	
	public void EncryptWithAesCbc() {
		Aes key = Aes.Create();
		//ok: use_ecb_mode
		key.Mode = CipherMode.CBC;
		using var encryptor = key.CreateEncryptor();
		byte[] msg = new byte[32];
		var cipherText = encryptor.TransformFinalBlock(msg, 0, msg.Length);
	}
	
	public void EncryptWithAesCbc2() {
		Aes key = Aes.Create();
		byte[] msg = new byte[32];
		byte[] iv = new byte[16];
		//ok: use_ecb_mode
		var cipherText = key.EncryptCbc(msg, iv, PaddingMode.PKCS7);
	}
	
	public void DecryptWithAesCbc(byte[] cipherText) {
		Aes key = Aes.Create();
		//ok: use_ecb_mode		
		key.Mode = CipherMode.CBC;
		using var decryptor = key.CreateDecryptor();
		var msg = decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);
	}
	
	public void DecryptWithAesCbc2(byte[] cipherText, byte[] iv) {
		Aes key = Aes.Create();
		//ok: use_ecb_mode		
		var msgText = key.DecryptCbc(cipherText, iv, PaddingMode.PKCS7);
	}	
	
	public static void Main()
	{
		Console.WriteLine("Hello World");
	}
}