easy to adopt, easy to use, easy to leave
service description
Cross Domain
Security Zone
IaaS
version 6.0
Open
Contents
Highlights .............................................................................................................................. 3
Overview ............................................................................................................................... 3
Example use cases ............................................................................................................... 5
Information assurance........................................................................................................... 5
Product features.................................................................................................................... 6
Technical features................................................................................................................. 6
Backup / Recovery & Disaster Recovery ............................................................................... 7
Service levels ........................................................................................................................ 7
Roles & Responsibilities ........................................................................................................ 8
Pricing ................................................................................................................................... 8
Trial service ........................................................................................................................ 10
Appendix ............................................................................................................................. 11
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Highlights

Cloud ready Cross Domain Guard option, managed by Skyscape provides a quick
and easy way to use structured and inspectable HTTP based data flows between
security domains

A DIY option, comprising a secure environment enabling consumers to implement
application specific cross domain solutions to provide secure and controlled
access between security domains

Optimised for OFFICIAL – hosted in the UK & operated by SC cleared staff, the
service benefits from extensive independent validation (including CESG Design
Review and CHECK tests) and alignment with CESG Cloud Security Principles
making it the ideal service for systems classified at OFFICIAL (including
OFFICIAL-SENSITIVE)

Enables and facilitate the Government Digital Strategy by providing a mechanism
for selected components of secure, PSN facing applications to be made available
via the Internet

Supports application specific cross-domain requirements such as complex data
types, code migration, browse-down remote administration, centralised logging,
and so on

Reduced risk of contamination as Skyscape apply governance and assurance that
each deployed solution meets the Skyscape Acceptable Use Policy and System
Interconnect Security Policy (i.e. code of connection)
Overview
The Skyscape Cross Domain Security Zone enables consumers to securely transfer data
between the Skyscape Assured OFFICIAL (PGA IL2) cloud platform and the Skyscape
Elevated OFFICIAL (PGA IL3) cloud platform using CESG approved cross domain security
patterns.
The Cross Domain Security Zone is designed to enable consumers to achieve the goals of
the Government Digital Strategy, specifically enabling PSN facing applications to be made
available to citizens and Industry via the Internet.
This service is available in two options:
1. Skyscape-managed Cross Domain Guard
Skyscape provide a secure and scalable managed Cross Domain Guard which supports
structured and inspectable HTTP based data flows. This option provides an immediately
available multi-tenant Cross Domain Guard to support simple use-cases.
2. Self-managed Cross Domain Solution
Skyscape provide self-service access to the Cross Domain Security Zone which enables
consumers to create their own Cross Domain Solution using technology and application
services of their choice. Skyscape provide an assurance wrap by managing firewalls
between the security zones and ensuring consumers use appropriate risk management
to understand and mitigate identified risks.
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The two options are shown in figure 1 (below),
PSN Protected
Service
Internet
Internet Servers
PSN Servers
Structured &
Inspectable HTTP
App
Data Copy
Structured &
Inspectable HTTP
App
Skyscape-managed
Cross Domain Guard
Complex & Varied
data flow
Complex & Varied
data flow
Master Data
Self-managed Cross
Domain Solution
Assured OFFICIAL
Cloud Platform
Cross Domain
Security Zone
Elevated OFFICIAL
Cloud Platform
Figure 1 - Cross Domain Security Zone
The service leverages the proven Skyscape Assured Cloud platform which provides the
following benefits:

UK Sovereign cloud platform delivered from two secure UK data centres by a UK
company with SC cleared UK staff

Extensive assurance through independent validation and alignment with the CESG
Cloud Security Principles

Accredited PSN Service enabling secure, compliant access via government
community networks including N3, PSN Assured & PSN Protected networks
The Skyscape Cross Domain Security Zone provides high levels of assurance appropriate
for data classified as OFFICIAL or OFFICIAL-SENSITIVE.
Skyscape’s service has been designed specifically of for the UK public sector and is
available only to the UK public sector. The service supports and complies with all relevant
areas of the Government ICT Strategy and Information Principles for the UK Public Sector.
Skyscape’s datacentres are some of the most energy efficient in the world and as such
support the Green Government ICT Strategy in full.
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Example use cases
Simpler
Better
Cheaper
The Cross Domain Security
Zone enables consumers to
use the multi-tenant Skyscape
Cross Domain Guard for
requirements where
applications can be designed
to make inspectable web
services calls between the
security domains.
Consumers who require more
control and flexibility over what
is passed between security
domains can now design,
implement and manage their
own cross domain security
solution hosted in the
Skyscape managed Cross
Domain Security Zone. This
enables support for a wider
range of use-cases.
The Skyscape Cross Domain
Security Zone provides
consumers with a flexible and
cost-effective mechanism to
support the aims of the
Government Digital Strategy.
The service enables
consumers to avoid the costs
associated with manual cross
domain transfers such as the
‘swivel chair’ method
Information assurance
The Skyscape assured cloud platform is designed and optimised to meet the unique
information assurance needs of UK public sector organisations.

UK Sovereign cloud platform delivered from two secure UK data centres by a UK
company with SC cleared UK staff

Suitable for all data classified at OFFICIAL, including OFFICIAL-SENSITIVE data
under the Government Security Classification Policy (GSCP)

Suitable for legacy IL2, IL3 and IL4 (by aggregation) systems under the Government
Protective Marking Scheme (GPMS)

Extensive independent validation of alignment with the CESG Cloud Security
Principles

Enables access between workloads hosted on IaaS services which are CESG Pan
Government Accredited at both IL2 & IL3 and are accredited PSN Services which
have secure, compliant access via both PSN Assured & PSN Protected networks

Independently certified against ISO27001, Cyber Essentials Plus and members of
the Cloud Security Alliance (CSA)

Secure (List X) and resilient (Tier 3) UK data centres facilities capable of hosting data
classified at SECRET

Protective Monitoring (aligned with GPG13) across all Skyscape platforms
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Product features
The Skyscape Cross Domain Security Zone provides a secure and flexible method of
transferring data between your workloads hosted on the Skyscape Assured OFFICIAL (PGA
IL2) cloud platform and the Skyscape Elevated OFFICIAL (PGA IL3) cloud platform. The
service provides the following features:

Assured – hosted in the UK & operated by SC cleared staff, the service benefits from
extensive independent validation (including CESG design reviews) that it is properly
aligned with CESG Cloud Security Principles making it the ideal service for all data
classified at OFFICIAL (including OFFICIAL-SENSITIVE)

Flexible – enables choice between ready-to-use Skyscape managed Cross Domain
Guard (Multi-Tenant) and bespoke self managed Single-Tenant Cross Domain
Security solutions

Cross Domain Guard – the Skyscape managed Cross Domain Guard supports wellstructured HTTP based data transfer such as XML

Cost-effective – the Skyscape Cross Domain Guard option is delivered as a cloud
service via a shared multi-tenant solution and benefits from usage based billing.

Control – the self-managed single-tenant option enables consumers to apply
bespoke controls to support a wider range of use-cases and traffic flows

Green – the Skyscape service is based in UK data centres which offer market
leading efficiency around power and cooling. A Skyscape solution will generate less
Carbon than many other solutions
Technical features
The Skyscape Cross Domain Security Zone provides the following technical features:

Based on CESG architectural patterns for cross domain security

Skyscape manage the firewalls on both the high side and low side of the Cross
Domain Security Zone to mitigate the risk of contamination

Skyscape require design reviews and agreement to Acceptable Use Policies to
provide assurance that the Elevated OFFICIAL (PGA IL3) cloud platform is
sufficiently protected from the Internet in line with CESG Cloud Security Principles

The Skyscape-managed Cross Domain Guard provides:

o
An immediately available solution based on technology from DeepSecure
o
A scalable and highly available solution distributed across multiple instances
o
Support for structured and inspectable content such as XML data
o
Support for both Low-to-High and High-to-Low data flows
The Self-managed single-tenant Cross Domain Solution provides:
o
An implementation of a ‘walled garden’ architecture for consumers to deploy
their own choice of gateway technology
o
The capability for consumers to design cross domain solutions to meet a
wider variety of use-cases and data flows
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o
Support for unstructured and un-inspectable content (subject to sufficient
additional mitigation) such as browse down Remote Desktop Protocol, code
transfer between security domains, import/export of complex data types (e.g.
video, images, etc)
o
Support for both Low-to-High and High-to-Low data flows

A highly available and disaster tolerant solution spanning two UK data centres
separated by over 100km

Integrated with the Skyscape Protective Monitoring solution (aligned with GPG13)

Enables solution to leverage multiple connectivity options including the Internet,
government community networks such as PSN Assured, PSN Protected, Legacy
GCF networks (e.g. GSI, GSE, PNN, etc) or N3
Backup / Recovery & Disaster Recovery
The Skyscape Cross Domain Security Zone is hosted across two UK data centres
(separated by over 100km).
The Skyscape-managed Cross Domain Guard is available within each UK data centre and
enables consumers to create highly available and disaster tolerant solutions.
Consumers can design self-managed Cross Domain Solutions to work across the Cross
Domain Security Zone in each UK data centre to provide a highly available and disaster
tolerant solution.
Service levels
Skyscape provide both an Availability SLA and Response Time SLA for the Cross Domain
Security Zone as per the following table.
STANDARD
Availability (monthly*)
Incident response
Service credits
99.90%
P1 – within 15 minutes
P2 – within 4 hours
P3 – within 24 hours
P4 – within 72 hours
10% of monthly spend on the
Cross Domain Security Zone
* Availability indication based on an average 730hrs per month. Excludes planned &
emergency maintenance. Unavailability applies to the Skyscape Managed Cross Domain
Guard or the underlying Cross Domain Security Zone infrastructure due to a fault recognised
at the IaaS layer or lower:

i.e. fault is not within the Consumers control (VM configuration, customer networks,
application logic, etc)

fault is within Skyscape controlled components such as the Cross Domain Security
Zone hardware, Cross Domain Guard service, data centre facilities, physical firewalls
& routers etc.
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
External connectivity providers (e.g. internet, PSN, N3) are also not included in the
availability calculation.
In addition, Skyscape also provide an Availability Service Level Target on the Skyscape
Portal i.e. the ability to log into the portal to create support tickets and use other functions.
Target Availability (monthly*)
Client Portal Availability (monthly)
99.90%
Roles & Responsibilities
Self Managed Cross
Domain Solution
Skyscape Managed
Cross Domain Guard
Provision of physical Cross Domain
Security Zone environment (network,
servers, storage & hypervisor)
Skyscape
Skyscape
Configuration and Management of interzone firewalls (e.g. whitelists)
Skyscape
Skyscape
Provision of security gateway solution
Consumer
Skyscape
Configuration and Management of
security gateway solution (e.g.
DeepSecure WebGuard)
Consumer
Skyscape
Assurance of underlying Cross Domain
Security Zone
Skyscape
Skyscape
Assurance of security gateway solution
Consumer
Skyscape
Documented requirements and
associated solution design
Consumer
Consumer
Assurance wrap including design review
and SIRO approval
Skyscape & Consumer
Skyscape & Consumer
Pricing
The Skyscape Cross Domain Security Zone is available in two options:
1. Skyscape-managed Cross Domain Guard
The Cross Domain Guard is a multi-tenant solution designed to support structured and
inspectable HTTP based data such as XML. It is priced as follows:
Data Volume
Monthly Price
Starter Pack (1TB)
£500
Next 4000GB
£0.50 per GB
5001GB+
£0.10 per GB
Upgrade options:

Dual Site: £500 per month
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Worked Example:
Consumer requires a Skyscape-managed Cross Domain Guard and will transfer 2500GB
per month
Consumer buys:

1 x First 1000GB @ £500 per month

1500GB @ £0.50 per GB = £750 per month

Total = £1,250 per month
2. Self-managed Cross Domain Solution
The self-managed Cross Domain Solution enables consumers to create their own
(single-tenant) solutions. It is priced as follows:

On-boarding / Setup Fee: £2,500 (Managed Firewall configuration and validation of
Assurance Plan)

Baseline Monthly Fee: £500

Plus VM fees as follows:
vCPU
(2GHz)
RAM
(GB)
STANDARD
(per month)
Tiny
1
2
£150.00
Small
2
4
£250.00
Medium
4
8
£350.00
Medium High
Memory
4
16
Large
8
16
Large High
Memory
8
32
Tier 1 Apps
Small
8
48
Tier 1 Apps
Medium
8
64
Tier 1 Apps
Large
8
96
£500.00
£750.00
£1,000.00
£1,500.00
£2,000.00
£3,000.00
Worked Example:
Consumer requires a self-managed Cross Domain Solution comprising of 4 x Medium VMs
Consumer buys:

1 x Setup / On-boarding fee @ £2,500 one-off

1 x Baseline Fee @ £500 per month

4 x Medium VM @ £1,400 per month

Total = £2,500 one-off plus £1,900 per month
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Ancillary Options
The Skyscape Pricing Guide provides a comprehensive catalogue of pricing; including all
ancillary service options available to consumers when used in conjunction with the Skyscape
Cross Domain Security Zone. Ancillary options include:

Connectivity options including HybridConnect, PSN, N3, Internet, data centre
interconnect, etc.

SFIA rate card for ad-hoc services.
Other ancillary options are available and can be found in the Skyscape Pricing Guide.
Trial service
Due to complex assurance requirements related to this service, a trial service is not
available.
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Appendix
On-boarding and off-boarding

Evidence that the consumer will implement
and maintain a suitable & ongoing Assurance
Process and Governance regime to ensure
that Risks are regularly reviewed and controls
are regularly audited for effectiveness

Agreement that the consumer will perform a
suitably scoped IT Security Health Check
against the application using the Cross
Domain Guard solution

Confirmation by HMG customer and
associated industry partners of agreement to
Skyscape Acceptable Use Policy (AUP) and
System Interconnect Security Policy (SISP)
On-boarding
Due to the nature of this service, on acceptance of
an order, Skyscape will work with the consumer to
create an Assurance Plan for the Cross Domain
Security Zone to that states the consumer’s
responsibilities including:
For Skyscape-managed Cross Domain Guard:

Validation of clear business requirement by
the HMG customer (e.g. Department SIRO)

Confirmation that the application uses a
structured and inspectable HTTP based data
transfer (e.g. XML)

Agreement of policy definition (e.g. whitelist
source & destination addresses, content types
to allow, content size limits, XML schema, etc)

Evidence that the consumer will implement
and maintain suitable technology controls in
both the low-side domain and high-side
domain (e.g. Protective Monitoring, AntiMalware, Security Patches, etc)

Agreement that the consumer will perform a
suitably scoped IT Security Health Check
against the application using the Cross
Domain Guard solution
Skyscape will create the consumer’s Primary
Administrator account and send the consumer a
Welcome Pack which includes the URL for the
Skyscape Portal for access to the knowledge
centre and service management function.
For Self-managed Cross Domain Solution
(single-tenant):
Once enabled, the consumer’s Primary
Administrator can create additional administrator
users and configure the Cross Domain Security
Zone virtual data centre (i.e. virtual networks,
virtual firewalls, virtual machines, OS provisioning,
application configuration, etc) as required.
For Self-managed Cross Domain Solution
(single-tenant):
Off-boarding

Validation of clear business requirement by
the HMG customer (e.g. Department SIRO)
On termination of the Cross Domain Security
Zone, Skyscape will:

Creation of Data Flow Document to
understand how the application will use the
Cross Domain Security Zone

Agreement of the Skyscape managed firewall
configuration required between the low-side
domain & the Cross Domain Security Zone
and between the high-side domain & the
Cross Domain Security Zone (e.g. Firewall
Access Control List)
For Skyscape-managed Cross Domain Guard:

Consumer’s Risk Assessment of enabling this
gateway between their security domains


Consumer’s Risk Treatment plan detailing the
controls that they will implement to mitigate the
identified risks

Evidence that the consumer will implement
and maintain suitable technology controls in
both the low-side domain and high-side
domain (e.g. Protective Monitoring, AntiMalware, Security Patches, etc)
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

Remove Access Control Lists from Skyscape
managed firewalls around the Cross Domain
Security Zone (removal of whitelists)
Remove the policy definition on the Skyscape
managed Cross Domain Guard
For Self-managed Cross Domain Solution
(single-tenant):
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Service constraints
Training
The Skyscape Cross Domain Security Zone
service can only be used for connectivity between
Skyscape services such as Compute-as-aService, Hadoop-in-the-Cloud, etc.
Skyscape have created a number of videos, help
guides, manuals and FAQs to help train and
instruct users so that are up and running quickly
and easily.
The service is designed to operate only when the
following constrains are met:
Skyscape also have a number of Partners who
are able to deliver additional services such as
training, support and managed services.
Skyscape would be pleased to introduce you to
such partners where appropriate.

Configuration and management of application
services in both the low and high security
domain must be hardened with regular
security patches applied

Application services must use appropriate antimalware software which is regularly updated

Only specified traffic types will be allowed via
a Skyscape managed whitelist

The customer SIRO must understand and
accept the residual risks associated with this
solution
Skyscape will adhere to the following in terms of
maintenance windows;
“Planned Maintenance” means any pre-planned
maintenance of any infrastructure relating to the
Services. Skyscape shall provide the Client with at
least twenty four (24) hours’ advance notice of
any such planned maintenance:
Ordering and invoicing
Billing for the service is monthly in arrears based
on either the amount of traffic sent through the
Cross Domain Guard or the maximum number of
virtual machines configured (running or not) at any
time during the month for the Cross Domain
Solution.
Payment can be via Purchase Order and Direct
Debit. Skyscape are preparing to be able to
accept Debit/Credit Card payments (e.g.
Government Procurement Card) – please enquire
at time of order to check whether this is available.
Planned maintenance of Skyscape’s infrastructure
relating to the Services shall happen between the
hours of 00:00 and 06:00 (UK local time) Monday
to Sunday and/or between the hours of 08:00 and
12:00 (UK local time) on a Saturday and/or
Sunday. No planned maintenance will take place
on a Saturday unless agreed in advance by both
parties;
Service lead time
Planned Maintenance shall be excluded from any
availability calculation in regard to service credits
but shall be included in the monthly service
reporting;
Due to the variable nature of this service, full onboarding of the consuming organisation including
enrolment of all users and end-user devices will
take an indeterminate amount of time.
“Emergency Maintenance” means any emergency
maintenance of any of the infrastructure relating to
the Services. Whenever possible, Skyscape shall
provide the Client with at least six (6) hours’
advance notice:
Termination
Whenever possible Emergency Maintenance of
Skyscape’s infrastructure will happen between the
hours of 00:00 and 06:00 (UK local time) Monday
to Sunday and/or between the hours of 08:00 and
12:00 (UK local time)on Saturday and/or Sunday
unless there is an identified and demonstrable
immediate risk to a Clients environment;
Emergency Maintenance shall be excluded from
any availability calculation in regard to service
credits but shall be included in the monthly service
reporting.
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Setting up a new consumer within the Skyscape
Portal will typically be completed within 4 hours
from acceptance of order.
Resources to validate the Assurance Plan activity
will be assigned within 10 days from acceptance
of order.
Terms
The Cross Domain Guard option is subject to a
minimum term of one month.
The Cross Domain Solution option is subject to a
minimum term of three months.
Consumers are required to provide notice of
termination of not less than 10 working days.
At the point of termination, consumers must
ensure that they have extracted any required data
from the ‘Cross Domain Solution’ virtual data
centre as Skyscape will ensure all consumer data,
accounts and access will be permanently deleted,
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and will not be able to be subsequently recovered
or restored.
Costs
An Early Exit charge will be payable if the contract
is terminated within the minimum term. The Early
Exit charge will be equal to the cost of 3 months
service less payments already made.
Consumers are responsible for extracting their
own data from the platform if required.
Skyscape may make an additional charge for
transferring data out of the service.
Consumer responsibilities
The control and management of access and
responsibilities for end users including appropriate
connectivity, security and assurance/accreditation
if required. Where access is required over
Government Secure Networks such as N3, legacy
GCF networks or PSN, the consumer is
responsible for adhering to the Code of
Connection.
Data restoration / service migration
For service migration, Skyscape allows existing
data to be migrated to and from the ‘Cross
Domain Solution’ virtual data centre.
In many circumstances, Skyscape can help
facilitate a bulk migration to the platform using
offline data ingest and extraction – please ask
Skyscape for details.
Financial recompense model
If the service level falls below the stated
availability percentage (excluding Planned and
Emergency maintenance periods), consumers will
be eligible for service credits on affected storage
only. Service credits will be calculated as a
percentage of the fees for the affected services for
the monthly billing period during which the failure
occurred (to be applied at the end of the billing
cycle).
Service Credit
Cross Domain
Security Zone
10% of monthly spend
on the Cross Domain
Security Zone
Providing evidence that suitable technology
controls in both the low-side domain and high-side
domain (e.g. Protective Monitoring, Anti-Malware,
Security Patches, etc) will be implemented and
maintained
Client Portal
1% of monthly spend
per 1% below service
level target or part
thereof
Ensuring a suitably scoped IT Security Health
Check against the application using the Cross
Domain Security Zone is performed
Technical requirements
Providing a clear business justification of the
requirement for a Cross Domain Security solution.
Providing evidence that suitable & ongoing
Assurance Process and Governance regime is
implemented and maintained to ensure that Risks
are regularly reviewed and controls are regularly
audited for effectiveness
Providing access requirements between the
‘Cross Domain Security Zone’ and consumer
solutions (e.g. firewall ports)
Consumers must ensure that systems in both
security domains meet the requirements of this
service:

Recommended use of a CPA approved data at
rest encryption solution

Mandatory use of anti-malware software
(regularly updated) to reduce risk of malicious
code execution on the servers

Recommended use of an enterprise audit and
monitoring service by the consuming
organisation to ensure security events are
centrally logged and reviewed.

Mandatory implementation of a Incident
Response plan by the consuming organisation
to respond to security incidents such as loss of
data confidentiality
Manage security incidents related to the use of
this service (e.g. data breach)
The consumer is also responsible for ensuring
only appropriate data (e.g. OFFICIAL or
OFFICIAL-SENSITIVE) is stored and processed
by applications on this environment and that they
comply with the Skyscape Security Operating
Procedures (SyOps) and other information
assurance requirements as specified in Skyscape
System Interconnect and Security Policy (SISP)
and associated accreditation documentation sets.
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Skyscape Cloud Services Limited
A8 Cody Technology Park
Ively Road
Farnborough
Hampshire
GU14 0LX
+44 (0)1252 303300
info@skyscapecloud.com
www.skyscapecloud.com
@skyscapecloud
© Skyscape Cloud Services Limited.
All Rights Reserved.
SC-SVC-06