Secure Deployment Guide for the Citrix Cloud Platform

The Secure Deployment Guide for Citrix Cloud provides an overview of security best practices when using Citrix Cloud and describes the information Citrix Cloud collects and manages.

The following articles provide similar information for other services in Citrix Cloud:

Control Plane

Guidance for administrators

  • Use strong passwords and regularly change your passwords.
  • All administrators within a customer account can add and remove other administrators. Ensure that only trusted administrators have access to Citrix Cloud.
  • Administrators of a customer have, by default, full access to all services. Some services provide a capability to restrict the access of an administrator. Consult the per-service documentation for more information.
  • Two-factor authentication for administrators is achieved using Citrix Cloud’s integration with Azure Active Directory.

Encryption and key management

The control plane does not store sensitive customer information. Instead, Citrix Cloud retrieves information such as administrator passwords on-demand (by asking prompting the administrator explicitly). There is no data-at-rest that is sensitive or encrypted, and thus you do not need to manage any keys.

For data-in-flight, Citrix uses industry standard TLS 1.2 with the strongest cipher suites. Customers cannot control the TLS certificate in use, as Citrix Cloud is hosted on the Citrix-owned cloud.com domain. To access Citrix Cloud, customers must use a browser capable of TLS 1.2 with strong cipher suites.

Consult the per-service documentation for details about encryption and key management within each service.

Data sovereignty

The Citrix Cloud control plane is hosted in the United States and in the European Union. Customers do not have control over this.

The customer owns and manages the resource locations that they use with Citrix Cloud. A resource location can be created in any data center, cloud, location, or geographic area the customer desires. All critical business data (such as documents, spreadsheets, and so on) are stored in resource locations and are under customer control.

For Content Collaboration, consult the following resources for information about controlling where the data resides:

Other services may have an option to store data in different regions. Consult the Geographical Considerations topic or the Technical Security Overviews (listed at the beginning of this article) for each service.

Audit and change control

There is currently no customer-visible auditing or change control available in the Citrix Cloud user interface or APIs.

Citrix has extensive internal auditing information. If a customer has a concern, they are advised to contact Citrix within 30 days. Citrix will review the audit logs to determine the administrator who performed an operation, the date on which it was performed, the IP address associated with the action, and so on.

Security issues insight

The web site status.cloud.com provides transparency into security issues that have an ongoing impact on the customer. The site logs status and uptime information. There is an option to subscribe for updates to the platform or individual services.

Citrix Cloud Connector

Installing the Cloud Connector

For security and performance reasons, Citrix recommends that customers do not install the Cloud Connector software on a domain controller.

Additionally, the machines on which the Cloud Connector software is installed should be inside the customer’s private network and not in the DMZ. For network and system requirements and instructions for installing the Cloud Connector, see Citrix Cloud Connector.

Configuring the Cloud Connector

The customer is responsible for keeping the machines on which the Cloud Connector is installed up-to-date with Windows security updates.

Customers can use antivirus alongside the Cloud Connector. Citrix tests with McAfee VirusScan Enterprise + AntiSpyware Enterprise 8.8. Citrix will support customers who use other industry standard AV products.

In the customer’s Active Directory (AD) the Cloud Connector’s machine account should be restricted to read-only access. This is the default configuration in Active Directory. Additionally, the customer can enable AD logging and auditing on the Cloud Connector’s machine account to monitor any AD access activity.

Logging on to the machine hosting the Cloud Connector

The Cloud Connector contains sensitive security information such as administrative passwords. Only the most privileged administrators should be able to log on to the machines hosting the Cloud Connector (for example, to perform maintenance operations). In general, there is no need for an administrator to log on to these machines to manage any Citrix product. The Cloud Connector is self-managing in that respect.

Do not allow end users to log on to machines hosting the Cloud Connector.

Installing additional software on Cloud Connector machines

Customers can install antivirus software and hypervisor tools (if installed on a virtual machine) on the machines where the Cloud Connector is installed. However, Citrix recommends that customers do not install any other software on these machines. Other software creates additional possible security attack vectors and might reduce the security of the overall Citrix Cloud solution.

Inbound and outbound ports configuration

The Cloud Connector requires outbound port 443 to be open with access to the internet. The Cloud Connector should have no inbound ports accessible from the Internet.

Customers can locate the Cloud Connector behind a web proxy for monitoring its outbound Internet communications. However, the web proxy must work with SSL/TLS encrypted communication.

The Cloud Connector might have additional outbound ports with access to the Internet. The Cloud Connector will negotiate across a wide range of ports to optimize network bandwidth and performance if additional ports are available.

The Cloud Connector must have a wide range of inbound and outbound ports open within the internal network. The table below lists the base set of open ports required.

Client Port(s) Server Port Service
49152 -65535/UDP 123/UDP W32Time
49152 -65535/TCP 135/TCP RPC Endpoint Mapper
49152 -65535/TCP 464/TCP/UDP Kerberos password change
49152 -65535/TCP 49152-65535/TCP RPC for LSA, SAM, Netlogon (*)
49152 -65535/TCP/UDP 389/TCP/UDP LDAP
49152 -65535/TCP 636/TCP LDAP SSL
49152 -65535/TCP 3268/TCP LDAP GC
49152 -65535/TCP 3269/TCP LDAP GC SSL
53, 49152 -65535/TCP/UDP 53/TCP/UDP DNS
49152 -65535/TCP 49152 -65535/TCP FRS RPC (*)
49152 -65535/TCP/UDP 88/TCP/UDP Kerberos
49152 -65535/TCP/UDP 445/TCP SMB

Each of the services used within Citrix Cloud will extend the list of open ports required. For more information, consult the following resources:

Monitoring outbound communication

The Cloud Connector communicates outbound to the Internet on port 443, both to Citrix Cloud servers and to Microsoft Azure Service Bus servers.

The Cloud Connector communicates with domain controllers on the local network that are inside the Active Directory forest where the machines hosting the Cloud Connector reside.

During normal operation, the Cloud Connector communicates only with domain controllers in domains that are listed as Use for subscriptions on the Identity and Access Management page in the Citrix Cloud user interface.

In selecting the domains to configure as Use for subscriptions, the Cloud Connector communicates with domain controllers in all domains in the Active Directory forest where the machines hosting the Cloud Connector reside.

Each service within Citrix Cloud extends the list of servers and internal resources that the Cloud Connector might contact in the course of normal operations. Additionally, customers cannot control the data that the Cloud Connector sends to Citrix. For more information about services’ internal resources and data sent to Citrix, consult the following resources:

Viewing Cloud Connector logs

Any information relevant or actionable to an administrator is available in the Windows Event Log on the Cloud Connector machine.

View installation logs for the Cloud Connector in the following directories:

  • %AppData%\Local\Temp\CitrixLogs\CloudServicesSetup
  • %windir%\Temp\CitrixLogs\CloudServicesSetup

Logs of what the Cloud Connector sends to the cloud are found in %ProgramData%\Citrix\WorkspaceCloud\Logs.

The logs in the WorkspaceCloud\Logs directory are deleted when they exceed a specified size threshold. The administrator can control this size threshold by adjusting the registry key value for HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\CloudServices\AgentAdministration\MaximumLogSpaceMegabytes.

SSL/TLS Configuration

The base Cloud Connector configuration does not need any special SSL/TLS configuration.

The Cloud Connector must trust the certification authority (CA) used by Citrix Cloud SSL/TLS certificates and by Microsoft Azure Service Bus SSL/TLS certificates. Citrix and Microsoft might change certificates and CAs in the future, but will always use CAs that are part of the standard Windows Trusted Publisher list.

Each service within Citrix Cloud may have different SSL configuration requirements. For more information, consult the Technical Security Overviews for each service (listed at the beginning of this article).

Security compliance

To ensure security compliance, the Cloud Connector will self-manage. Do not disable reboots or put other restrictions on the Cloud Connector. These actions prevent the Cloud Connector from updating itself when there is a critical update.

The customer is not required to take any other action to react to security issues. The Cloud Connector automatically applies any security fixes.

Guidance for handling compromised accounts

  • Audit the list of administrators in Citrix Cloud and remove any who are not trusted.
  • Disable any compromised accounts within your company’s Active Directory.
  • Contact Citrix and request rotating the authorization secrets stored for all the customer’s Cloud Connectors. Depending on the severity of the breach, take the following actions:
    • Low Risk: Citrix can rotate the secrets over time. The Cloud Connectors will continue to function normally. The old authorization secrets will become invalid in 2-4 weeks. Monitor the Cloud Connector during this time to ensure that there are no unexpected operations.
    • Ongoing high risk: Citrix can revoke all old secrets. The existing Cloud Connectors will no longer function. To resume normal operation, the customer must uninstall and reinstall the Cloud Connector on all applicable machines.

Secure Deployment Guide for the Citrix Cloud Platform