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author | Sebastien Jodogne <s.jodogne@gmail.com> |
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date | Mon, 11 Jan 2021 14:23:22 +0100 |
parents | 3b8b129fd721 |
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.. _security: Securing Orthanc ================ .. contents:: Orthanc is a microservice for medical imaging. Out-of-the-box, it makes the assumption that it runs on the localhost, within a secured environment. As a consequence, care must be taken if deploying Orthanc in a insecure environment, especially if it is run as a public-facing service on Internet. This page provides instructions to secure Orthanc through its :ref:`configuration options <configuration>`. General configuration --------------------- As for any service running on a computer, you should: * Make sure to run the Orthanc service as a separate user. In particular, never run Orthanc as the ``root`` user on GNU/Linux, or as the ``Administrator`` user on Microsoft Windows. * Contact your network administrators to setup `Intranet firewalls <https://en.wikipedia.org/wiki/Firewall_(computing)>`__, so that only trusted computers can contact Orthanc through its REST API or through the DICOM protocol. Care must also be taken about some configuration options specific to Orthanc: * ``LimitFindResults`` and ``LimitFindInstances`` should not be set to zero to avoid making Orthanc unresponsive on large databases by a malicious user that would make many lookups within Orthanc. A value of ``100`` should be a good compromise. * ``HttpsVerifyPeers`` should be set to ``true`` to secure outgoing connections to remote HTTPS servers (such as when Orthanc is acting as a :ref:`DICOMweb client <dicomweb-client>`). * Make sure to understand the implications of the ``OverwriteInstances`` option. * You might also be interested in checking the options related to :ref:`performance optimization <scalability>`. .. _security_http: Securing the HTTP server ------------------------ .. highlight:: lua Orthanc publishes a :ref:`REST API <rest>` that provides full programmatic access to its content, in read/write. This means for instance that a malicious user could delete the entire content of the server, or could inspect confidential medical data. By default, the HTTP server is restricted to the localhost to prevent such attacks from the outside world. However, as soon as external access is granted by setting the ``RemoteAccessAllowed`` configuration option to ``true``, you should: * Set ``AuthenticationEnabled`` to ``true`` to force the users to authenticate. The authorized users are listed in the option ``RegisteredUsers``. * Enable :ref:`HTTPS encryption <https>` to prevent the stealing of medical data or passwords, even on the Intranet. * If Orthanc is put on a server that can be contacted from Internet, put Orthanc behind a :ref:`reverse proxy <https>`, and let this reverse proxy take care of the HTTPS encryption. * Enable :ref:`Client certificate authentication <https>` between multiple Orthanc peers. * Consider turning of the :ref:`embedded WebDAV server <webdav>` by setting configuration option ``WebDavEnabled`` to ``false``. * Setup rules that define, for each authorized user, which resources it can access, and through which HTTP method (GET, POST, DELETE and/or PUT). This can be done by defining a :ref:`filter written in Lua <lua-filter-rest>`. Here is a sample Lua filter that differentiates between an administrator user (``admin``) who has full access on the localhost only, and a generic user (``user``) that has only read-only access:: function IncomingHttpRequestFilter(method, uri, ip, username, httpHeaders) if method == 'GET' and (username == 'user' or username == 'admin') then -- Read-only access (only GET method is allowed) return true elseif username == 'admin' and ip == '127.0.0.1' then -- Read-write access for administrator (any HTTP method is allowed on localhost) return true else -- Access is disallowed by default return false end end Very importantly, make sure to protect ``POST`` access to the ``/tools/execute-script`` URI. This URI can indeed be used by a malicious user to execute any system command on the computer as the user that runs Orthanc. * Consider implementing a :ref:`higher-level application <improving-interface>` (e.g. in PHP, Java, Django...) that takes care of user authentication/authorization, and that is the only one to be allowed to contact the Orthanc REST API. In particular, you must create a higher-level application so as to properly deal with `CSRF attacks <https://en.wikipedia.org/wiki/Cross-site_request_forgery>`__: Indeed, as explained in the introduction, Orthanc is a microservice that is designed to be used within a secured environment. * For advanced scenarios, you might have interest in the :ref:`advanced authorization plugin <authorization>`. Similarly, developers of :ref:`plugins <plugins>` could be interested by the ``OrthancPluginRegisterIncomingHttpRequestFilter2()`` function provided by the Orthanc plugin SDK. **Remark:** These parameters also apply to the :ref:`DICOMweb server plugin <dicomweb>`. Securing the DICOM server ------------------------- .. highlight:: json Besides its REST API that is served through its embedded HTTP/HTTPS server, Orthanc also acts as a :ref:`DICOM server <dicom-protocol>` (more precisely, as a DICOM SCP). In general, the DICOM protocol should be disabled if running Orthanc on a cloud server, except if you use a VPN (cf. `reference <https://groups.google.com/d/msg/orthanc-users/yvHexxG3dTY/7s3A7EHVBAAJ>`__) or a SSH tunnel (cf. `reference <https://www.howtogeek.com/168145/how-to-use-ssh-tunneling/>`__). Favor HTTPS for transfering medical images across sites (see above). You can turn off DICOM protocol by setting the configuration option ``DicomServerEnabled`` to ``false``. The DICOM modalities that are known to Orthanc are defined by setting the ``DicomModalities`` configuration option. Out-of-the-box, Orthanc accepts C-ECHO and C-STORE commands sent by unknown modalities, but blocks C-FIND and C-MOVE commands issued by unknown modalities. To fully secure the DICOM protocol, you should: * Set the ``DicomAlwaysAllowEcho`` configuration option to ``false`` to disallow C-ECHO commands from unknown modalities. * Set the ``DicomAlwaysAllowStore`` configuration option to ``false`` to disallow C-STORE commands from unknown modalities. * Set the ``DicomCheckModalityHost`` configuration option to ``true`` to validate the IP and hostname address of the remote modalities. * For each modality that is defined in ``DicomModalities``, selectively specify what DICOM commands are allowed to be issued by the SCU of this modality by setting the suboptions ``AllowEcho``, ``AllowFind``, ``AllowMove``, ``AllowStore`` and ``AllowGet``. For instance, a modality could be allowed to C-STORE images, but be disallowed to C-FIND the content of Orthanc. Here is a sample configuration to define a single modality that is only allowed to send DICOM instances to Orthanc:: { "DicomModalities" : { "untrusted" : { "AET" : "CT", "Port" : 104, "Host" : "192.168.0.10", "AllowEcho" : false, "AllowFind" : false, "AllowMove" : false, "AllowGet" : false, "AllowStore" : true } } } **Note:** These configuration suboptions only affect the behavior of the DICOM SCP of Orthanc (i.e. for incoming connections). Orthanc will always be able to make outgoing DICOM SCU connections to these modalities, independently of the value of these suboptions. * Consider implementing a :ref:`filter implemented in Lua <lua-filter-rest>` to restrict which modalities can C-STORE images within Orthanc, and which kind of images are accepted by Orthanc. * Consider setting ``DicomCheckCalledAet`` to ``true`` to force proper configuration of remote modalities. **Remark:** As of Orthanc 1.8.2, `DICOM TLS encryption <https://www.dicomstandard.org/using/security/>`__ is not supported yet. As a temporary workaround, `it has been reported <https://www.digihunch.com/2020/11/medical-imaging-web-server-deployment-pipeline/>`__ that the "*SSL Termination for TCP Upstream Servers*" feature of nginx can be used to emulate DICOM TLS. Another option is to use `stunnel <https://www.stunnel.org/>`__. We are looking for :ref:`an industrial sponsor <contributing>` to implement DICOM TLS in the core of Orthanc, as this feature is dedicated to enterprise and cloud environments. Securing the storage -------------------- In general, for security, Orthanc should store its database index (PostgreSQL, SQLite...) and its :ref:`storage area <orthanc-storage>` for DICOM files on an `on-premises, self-hosted infrastructure <https://en.wikipedia.org/wiki/On-premises_software>`__ with `disk encryption <https://en.wikipedia.org/wiki/Disk_encryption>`__. Similarly, Orthanc itself should ideally run on your own on-premises infrastructure, and not on a virtual machine that is managed by a public cloud solution provider. Depending on your jurisdiction, it might be possible to move the storage area to a `cloud-based object storage <https://en.wikipedia.org/wiki/Object_storage>`__, by using the :ref:`dedicated storage plugins <object-storage>`. :ref:`Orthanc-side encryption <client-side-encryption>` should be enabled in such a situation. In any case, make sure to get legal advice that is very specific to the legislation of the countries where you are active (for illustration, check out the recent debates over the `privacy shield <https://en.wikipedia.org/wiki/EU%E2%80%93US_Privacy_Shield>`__ in Europe). Make sure to understand the implications of using cloud-based object storage, of using virtual machines in the cloud to store health data, of using managed database servers (even with so-called "encryption-at-rest" features)... As a free and open-source project, the Orthanc ecosystem cannot be taken as liable for any security breach or data leak in your deployments, for any misconfiguration, for any bad handling of personal/health data, for any bypassing of regulatory requirements, for not being compliant with your local legislation, or for any similar stuff: Orthanc is just software, security is your responsibility.