Some default values can be dangerous if you expose your environment in hostile networks, here is some steps to harden your environment.
See the example pentestrc file.

The default root password is toor, we can change it with Chef:
First we generate the password hash:

$ mkpasswd  -m sha-512 -S pentestenv -s <<< custom-password 
$6$pentestenv$2B8PIRYrG7XOMj8FQOHJ1hDMfniVVpgBVo70mes6mpTeNqApvCVUx6rS6gXojxLrsHqnwYavbJSjpd8HSUbHh1

Then, define the user password inside the elite cookbook:

kali:
  chef:
    recipes:
      - elite
    json:
      elite:
        users: [root]
        root:
          shell: /bin/bash
          password: $6$pentestenv$2B8PIRYrG7XOMj8FQOHJ1hDMfniVVpgBVo70mes6mpTeNqApvCVUx6rS6gXojxLrsHqnwYavbJSjpd8HSUbHh1

The default allowed SSH private key to connect to the kali instance is public and can be found here. Change it by:

Generate a custom key:

$ ssh-keygen -f ssh-keys/custom-key

Copy your SSH public key (without type & label cat ssh-keys/custom-key.pub|cut -d" " -f2) and add it in your provisioning step:

kali:
  chef:
    recipes:
      - pentest-env::authorized_keys
    json:
      pentest-env:
        authorized_keys:
          root:
            - AAAAB3NzaC1yc2EAAAADA[....]RHazdIlN

After provisioning, the default private key will not be allowed to connect to the Kali instance, we need to use our new key:

kali:
  ssh:
    private_key_path: ssh-keys/custom-key

Don't systematically connect your kali to public networks, only when required.

Source: https://phoenhex.re/2018-03-25/not-a-vagrant-bug

It is recommended to disable the SharedFoldersEnableSymlinksCreate feature globally by setting the environment variable VAGRANT_DISABLE_VBOXSYMLINKCREATE=1 in your profile.

All pentest-env targets which doesn't require provisionning (prebuilt boxes like vulnhub, metasploitable, etc..) disable the default vagrant shared folder. In case it is required, it can be re-enabled by defining a volume in the pentestrc resource file:

mytarget:
  volumes:
    .: /vagrant

All volumes defined in your pentestrc resources will automatically disable the SharedFoldersEnableSymlinksCreate feature (with the shared_folder's SharedFoldersEnableSymlinksCreate: false option).