Clone the key first.

Author: tyranid

NtApiDotNet/Win32/Security/Authentication/Kerberos/KerberosKey.cs

@@ -259,6 +259,8 @@ internal static byte[] DeriveAesKey(byte[] base_key, byte[] folded_key)
             Aes encrypt = new AesManaged();
             encrypt.Mode = CipherMode.ECB;
 
+            folded_key = (byte[])folded_key.Clone();
+
             byte[] ret = new byte[base_key.Length];
             var transform = encrypt.CreateEncryptor(base_key, new byte[16]);
             transform.TransformBlock(folded_key, 0, 16, folded_key, 0);