Cloud Deployment

With cloud deployments you can create a proper SSL certificate using the free Let’s Encrypt CA. This eliminates the bad certificate browser warning seen in the Self Signed Deployment method. Velociraptor uses the Let’s Encrypt protocol to obtain and manage its own certificates (and automatically rotate them when they expire).

Before You Begin

Note the following requirements:

  • You must use a DNS name as Let’s Encrypt will not issue a certificate for an IP address. The DNS name can be a Dynamic DNS name managed by Google Domains.
  • Ports 80 and 443 must publicly accessible. Let’s Encrypt uses both ports to issue certificates.
  • You can optionally configure Authentication via SSO providers.

Provision a Virtual Machine

Next we provision an Ubuntu VM from any cloud provider. The size of your VM depnds on the number of endpoints in your environment. An 8 or 16Gb VM should be sufficient for around 5-10k clients. Additionally you will need sufficient disk space to hold the data you collect. We recommend starting with a modest amount of storage and then back up data or increase the storage volume as needed.

Our virtual machine must be able to receive connections over both ports 80 and 443. Be sure to check inbound filtering Access Control Lists to ensure that access is allowed. When using SSL, both the client communication and the Admin GUI are served over the same ports to benefit from SSL transport encryption. The Let’s Encrypt protocol requires Let’s Encrypt’s servers to connect to the VM on port 80 - however the Admin GUI will only be served over SSL.

Get a domain name

An SSL certificate says that the DNS name is owned by the server that presents it. Since you cannot currently get a Let’s Encrypt certificate for an IP address. you’ll need buy a DNS domain from any provider. You’ll then need to set up a DNS A Record to point at your Velociraptor server’s external IP. You can use a dynamic DNS client such as ddclient to update your DNS->IP mapping dynamically. Alternatively, Velociraptor directly supports updating Google Domains Dynamic DNS so this is the easiest option since it requires the least amount of configuration. In this example we use Google Domains to purchase our domain, but any other domain provider would work as well.

Assign an IP

You can deploy a Virtual Machine over a static IP address or allow the cloud provider to assign a dynamic IP address. If you use a dynamic IP address you must also configure Dynamic DNS. Google Domains allows you to assign a dynamic DNS entry for our domain by selecting a Dynamic DNS record:

DynDNS Dashboard
DynDNS Dashboard

After the dynamic address is created, you need to get the credentials for updating the IP address from the console. You will use these credentials during the interactive configuration process below.

Configure Velociraptor to use Let’s Encrypt

Let’s Encrypt allows Velociraptor to issue its own certificates. Selecting the Let’s Encrypt option ensures:

  • The server will fetch certificates automatically from Let’s Encrypt’s servers when first accessed by the browser.
  • Both the Frontend and GUI will be served over the standard SSL port (443).
  • The GUI is externally available, but protected over SSL.
  • Clients will connect to the public DNS name over SSL.

Use the guided configuration wizard to select this operation mode:

$ ./output/velociraptor config generate -i
?
Welcome to the Velociraptor configuration generator
---------------------------------------------------

I will be creating a new deployment configuration for you. I will
begin by identifying what type of deployment you need.

  [Use arrows to move, space to select, type to filter]
  Self Signed SSL
> Automatically provision certificates with Lets Encrypt

You must have both ports 80 and 443 publicly accessible by allowing any inbound firewall rules! Letsencrypt uses both to issue certificates. If you forgot to open port 80, Letsencrypt will fail to issue the certificate and this might result in blocking the domain name from getting an SSL certificate for several days. If you find this happened, simply change the dyndns name and start again.

The first time you connect to the Admin GUI or to the frontend, the server will obtain its own certificates from Let’s Encrypt. You should see no SSL warnings in your browser.

Configuring Google OAuth SSO

In the previous sections you set up Velociraptor’s GUI over SSL. Next, you need to create users and assign them passwords manually. The trouble with user account management is that we cannot enforce 2-factor authentication, password policies, or any of the usual enterprise requirements for user account management. Users who have to remember too many passwords may be inclined to use an easily guessable password.

Most enterprise systems require an SSO mechanism to manage user accounts and passwords. Manual user account management simply does not scale.

Velociraptor supports a number of choices of authentication providers:

  1. Basic Authentication - this stores usernames and passwords in Velociraptor’s own datastore.
  2. Google, Azure or GitHub OAuth2 providers - these providers authenticate users via OAuth2.
  3. OIDC - uses the Open ID Connect protocol to support many IAM providers (e.g. Okta)

OAuth Identity management

In the following sections, we demonstrate how Velociraptor can be configured to use Google’s OAuth mechanism to verify a user’s identity. This requires a user to authenticate to Google via their usual method - if their account requires 2 factor authentication, then users need to log in this way.

Once the user authenticates to Google, they are redirected back into the Velociraptor application with a token that allows the application to request information about the user (for example, the username or email address).

OAuth is an authentication protocol. This means Velociraptor can be pretty confident the user is who they claim they are. However, this does not automatically grant them access to the application. A Velociraptor administrator must still manually grant user access before a user can log in.

Before using Google to authenticate, you need to register your Velociraptor deployment as an OAuth App with Google.

Registering Velociraptor as an OAuth application

Register Velociraptor as an OAuth app by accessing the Google cloud console at https://console.cloud.google.com. You must set up a cloud account and create a cloud project even if you do not host your server on Google’s Cloud Platform.

Your ultimate goal is to obtain OAuth credentials to give our Velociraptor app, there are a few things set up first. Navigate to APIs and Services in the GCP console and select Credentials and the OAuth Consent Screen tab.

Creating application credentials
Creating application credentials

Further down you need to provide an authorized domain

Authorizing domains
Authorizing domains

In order to add an Authorized domain you need to verify it. Google’s help pages explain it further:

Authorized domains: To protect you and your users, Google restricts your OAuth 2.0 application to using Authorized Domains. If you have verified the domain with Google, you can use any Top Private Domain as an Authorized Domain.

In this example we assume that you purchased your domain with Google domains which makes this step easier since it is already verified.

We can go back to the cloud console and Create Credentials/OAuth client ID:

Creating OAuth2 client ID
Creating OAuth2 client ID

Now select Web App and set the Authorized redirect URIs to https://<Your Domain Name>/auth/google/callback - This is the URL that successful OAuth authentication will redirect to. Velociraptor accepts this redirect and uses it to log the user on.

Specifying the redirect URL
Specifying the redirect URL

If all goes well the Google cloud console will give us a client ID and a client secret.

Generating configuration

To generate a self signed deployment, start by running the config generate command to invoke the configuration wizard

velociraptor config generate -i

Generating Cloud Deployment
Generating Cloud Deployment

The configuration wizard asks a number of questions and creates a server and client configuration.

  • What OS will the server be deployed on? This choice will affect the defaults for various options. Production deployments are typically done on a Linux machine (but the configuration can be generated on Windows).
  • Path to the datastore directory: Velociraptor uses flat files for all storage. This path is where Velociraptor will write the files. You should mount any network filesystems or storage devices on this path.
  • The public DNS name of the Frontend: The clients will connect to the server using this DNS name so it should be publically accessible (Note this is a DNS name and not a URL).
  • Google OAuth2 Client ID and Secret are obtained from above.
  • GUI Username or email address to authorize: The initial set of administrator accounts can be stored in the configuration file. When Velociraptor starts it will automatically add these accounts as administrators. When using SSO, Velociraptor does not use any passwords so only the user names will be recorded.

Grant Access to Velociraptor

The OAuth flow ensures the user’s identity is correct but does not give them permission to log into Velociraptor. Note that having an OAuth enabled application on the web allows anyone with a Google identity to authenticate to the application but the user is still required to be authorized explicitly. If a user is rejected, we can see the following in the Audit logs:

   {
     "level": "error",
     "method": "GET",
     "msg": "User rejected by GUI",
     "remote": "192.168.0.10:40570",
     "time": "2018-12-21T18:17:47+10:00",
     "user": "mike@velocidex.com"
   }

In order to authorize the user we must explicitly add them using the Velociraptor Admin tool:

$ velociraptor --config ~/server.config.yaml user add mike@velocidex.com
Authentication will occur via Google - therefore no password needs to be set.

Note that this time, Velociraptor does not ask for a password at all, since authentication occurs using Google’s SSO. If we hit refresh in the browser we should be able to see the Velociraptor application dashboard.

We can see that the logged in user is authenticated by Google, and we can also see the user’s Google avatar at the top right for some more eye candy :-).

Velociraptor Dashboard
Velociraptor Dashboard

Velociraptor will retain its OAuth token for 24 hours. Each day users will need to re-grant OAuth credentials. Therefore revoking a user from the Google Admin console may take a full day to take effect. To remove access sooner you should simply remove all permissions from the user using velociraptor user grant '{}'.

Deploying to the server

Once a server configuration file is created, you need to create a server Debian package embedding the config file. The Debian package the Velociraptor executable, the server configuration file and relevant startup scripts.

Run the following command to create the server:

velociraptor.exe --config server.config.yaml debian server --binary velociraptor-v0.6.0-linux-amd64

Make sure the debian file is well protected. A compromise of the file will leak private key material enabling a MITM attack against Velociraptor.

You can check the installation using service velociraptor_server status.

$ sudo dpkg -i velociraptor_0.3.0_server.deb
Selecting previously unselected package velociraptor-server.
(Reading database ... 384556 files and directories currently installed.)
Preparing to unpack velociraptor_0.3.0_server.deb ...
Unpacking velociraptor-server (0.3.0) ...
Setting up velociraptor-server (0.3.0) ...
Created symlink /etc/systemd/system/multi-user.target.wants/velociraptor_server.service → /etc/systemd/system/velociraptor_server.service.

$ sudo service velociraptor_server status
● velociraptor_server.service - Velociraptor linux amd64
   Loaded: loaded (/etc/systemd/system/velociraptor_server.service; enabled; vendor preset: enabled)
   Active: active (running) since Sun 2019-07-07 08:49:24 AEST; 17s ago
 Main PID: 2275 (velociraptor)
    Tasks: 13 (limit: 4915)
   Memory: 30.2M
   CGroup: /system.slice/velociraptor_server.service
           └─2275 /usr/local/bin/velociraptor --config /etc/velociraptor/server.config.yaml frontend

Jul 07 08:49:24 mic-Inspiron systemd[1]: Started Velociraptor linux amd64.

If you prefer to use Windows for your day to day work, you can build the Debian package on your windows machine but you must specify the --binary flag to the debian server command with a path to the linux binary. You can obtain a copy of the linux binary from the Github releases page.