Security Design Considerations

Security is a high priority for customers in a multi-tenant environment. While virtual infrastructures are relatively secure in their basic installation, additional changes are required to adhere to certain security audit requirements. This section provides an overview of some of the security measures considered within the reference design, as they are subject to the wider security protocols required in an offering for managed services.

Hypervisor Hardening

VMware ESXi 5 is a small-footprint version of VMware’s hypervisor. This minimal footprint also reduces the attack surface. ESXi implements support for Intel TXT. The capability is managed and controlled by xStream software for trusted compute pools, providing visibility to the integrity of the platform and enforcement of trust policies for deployment and migration of virtual machines. The ESXi installation comes with a number of additional security features:

  • • LDAP integration
  • • Management interface firewall
  • • Lockdown mode
  • • Logging

These features have to be enabled corrected to ensure hardening. With the high priority attached to security in the multi-tenant paradigm being used in the cloud platform, using ESXi 5.x is recommended. In addition to this, basic security measures such as setting a strong root password should be used and compliance requirements that are necessary for compliance with the security standards selected for the platform are checked.

Firewalls and Network separation

To provide end-to-end separation of client data, it is important to ensure that no element in the infrastructure allows data to comingle or be accessed by another client. This is especially true of the networking design and infrastructure.

In order to achieve this, the reference design prescribes the infrastructure to be entirely separate from the customer VPN landing zone, through to the individual virtual machines and at all points in between. To achieve this, the reference design uses of the following technologies:

  • • VLAN
  • • Virtual switches
  • • Virtual appliances
  • • Firewalls and routing infrastructure

Every cloud customer is assigned one or more individual VLAN, as needed. Customer network traffic remains isolated from each other within a VLAN. The switch to which a VLAN is attached is also assigned the same VLAN tag. The only way for machines in VLAN A to talk to machines in VLAN B (and vice versa) is for the router to be configured to allow that conversation to occur. To ensure that the switch configuration is unified across all hosts in a cluster, the reference design uses distributed virtual switches. These ensure that the switch configuration associated VLAN tagged switch port groups are the same across all attached hosts, thereby limiting the chances of a misconfiguration of VLAN tagging on the virtual switch.

In addition to the VLAN tagging, the reference design also makes use of other traditional networking separation and security tools. A key technology is firewalling. Both virtual and physical firewalls are needed to ensure separations throughout the environment, from access to the physical network, including DMZ separation using physical firewall devices, and virtual firewalls to ensure visibility and separation across virtual machines.

Firewalls are required to scale to the highest VPN session counts, throughput, and connection speed and capacity to meet the needs of the most demanding customers. Offering protocol-agnostic client and clientless access for a broad spectrum of desktop and mobile platforms, the firewall device delivers a versatile, always-on remote access integrated with IPS and Web security for secure mobility and enhanced productivity.

The reference design ensures that throughout the network, be it virtual or physical, industry standard separation is enabled, and further guaranteed and improved by the inclusion of specific industry leading technologies that ensure even greater levels of granularity and visibility within the system.

Management Network Firewalling

For additional security, putting the hosts and management servers behind firewalls provides additional security and separation of the management services. Ports will be required to be opened for VMware virtual infrastructure to work.

Virtual Networking

VMware virtual infrastructure implements a virtual networking component that allows for virtual switches and port groups to be created at the software layer and operate as if they were physical infrastructure. There are certain features and ways to configure the networking to improve network segregation and prevent possible network vulnerabilities.

These are:

  • • Use VLAN tagging
  • • Disable MAC address changes
  • • Disable forged transmits
  • • Disable promiscuous mode
  • • Prevent and monitor for spoofing

Note that some of the features need to be enabled for certain customers— for example, for internal IDS scans—but should only be changed explicitly from defaults on an individual basis. As mentioned earlier, all customers will be assigned their own VLAN, and this will remain enabled. As a recommended practice, the reference design calls for use of different vSwitches to physically separate network traffic, disable forged transmits, and segregate management network traffic from virtual machine traffic.

Anti-Virus Software

Anti-virus and anti-malware software is always a consideration by any company when security is in question. For the management layer, anti-virus software is recommended on the virtual machine manager server and any other appropriate virtual machines. The definition of anti-virus policies and the deployment of anti-virus agents by a service provider to the tenant’s virtual machines fall outside the scope of this reference design. Tenant segregation and the use of security devices such as firewalls and IPSs—and, if selected, technologies such as virtual firewalls—will ensure that any viruses on a tenant’s virtual machines will not spread to other tenants. It is recommended that approved anti-virus software be installed on management layer virtual machines. Unless specified by the service provider, the tenant is generally responsible for installation of anti-virus software on production virtual machines.

Cloud Management Security

The cloud management layer provides the basis for all management functions surrounding the reference design. It ties into all the other technologies previously listed and provides some additional functionality to assist in the creation of a secure and auditable cloud environment. The security elements required by a cloud management portal are as follows:

  • • PCI/ISO/FedRAMP/NIST 800-53 associated security controls
  • • Governance, risk, and compliance (GRC)
  • • Trusted execution platform

Trusted execution platform is the one element that we have covered in depth in the earlier chapters, so we will not cover that here. Let’s cover the other two elements briefly in the next two sections.

Security Controls

The security controls implemented in the reference design are based on NIST 800-53/FedRAMP, GLB, iTAR/EAR, applicable security controls to measure and secure connectivity between data centres.

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