National Information Assurance Partnership
Common Criteria Evaluation and Validation Scheme
Validation Report
for the
Nubo Software Thin Client v2.0
Report Number: CCEVS-VR-10886-2018
Dated: July 23, 2018
Version: 0.1
National Institute of Standards and Technology National Security Agency
Information Technology Laboratory Information Assurance Directorate
100 Bureau Drive 9800 Savage Road STE 6940
Gaithersburg, MD 20899 Fort George G. Meade, MD 20755-6940
®
TM
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ACKNOWLEDGEMENTS
Validation Team
Linda Morrison
Brad O’Neill
The MITRE Corporation
Daniel Faigin
The Aerospace Corporation
Common Criteria Testing Laboratory
Anthony Busciglio
Muhammad Abdallah
Danielle F Canoles
Acumen Security
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Table of Contents
1 Executive Summary............................................................................................................... 4
2 Identification.......................................................................................................................... 5
3 Architectural Information .................................................................................................... 6
4 Security Policy........................................................................................................................ 7
5 Assumptions, Threats & Clarification of Scope ................................................................. 8
5.1 Assumptions....................................................................................................................................................8
5.2 Threats.............................................................................................................................................................8
5.3 Clarification of Scope.....................................................................................................................................8
6 Documentation..................................................................................................................... 10
7 TOE Evaluated Configuration ........................................................................................... 11
7.1 Evaluated Configuration..............................................................................................................................11
8 IT Product Testing............................................................................................................... 12
8.1 Developer Testing .........................................................................................................................................12
8.2 Evaluation Team Independent Testing.......................................................................................................12
9 Results of the Evaluation .................................................................................................... 13
9.1 Evaluation of Security Target .....................................................................................................................13
9.2 Evaluation of Development Documentation...............................................................................................13
9.3 Evaluation of Guidance Documents............................................................................................................13
9.4 Evaluation of Life Cycle Support Activities...............................................................................................14
9.5 Evaluation of Test Documentation and the Test Activity .........................................................................14
9.6 Vulnerability Assessment Activity ..............................................................................................................14
9.7 Summary of Evaluation Results..................................................................................................................14
10 Validator Comments & Recommendations ...................................................................... 15
11 Annexes................................................................................................................................. 16
12 Security Target .................................................................................................................... 17
13 Glossary ................................................................................................................................ 18
14 Bibliography......................................................................................................................... 19
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1 Executive Summary
This Validation Report (VR) is intended to assist the end user of this product and any security
certification Agent for that end user in determining the suitability of this Information Technology
(IT) product for their environment. End users should review the Security Target (ST), which is
where specific security claims are made, in conjunction with this VR, which describes how those
security claims were tested and evaluated and any restrictions on the evaluated configuration.
Prospective users should carefully read the Assumptions and Clarification of Scope in Section 5
and the Validator Comments in Section 10, where any restrictions on the evaluated configuration
are highlighted.
This report documents the National Information Assurance Partnership (NIAP) assessment of the
evaluation of the Nubo Software Thin Client Target of Evaluation (TOE). It presents the
evaluation results, their justifications, and the conformance results. This VR is not an
endorsement of the TOE by any agency of the U.S. Government and no warranty of the TOE is
either expressed or implied. This VR applies only to the specific version and configuration of
the product as evaluated and documented in the ST.
The evaluation was completed by Acumen Security in June 2018. The information in this report
is largely derived from the Evaluation Technical Report (ETR) and associated test report, all
written by Acumen Security. The evaluation determined that the product is both Common
Criteria Part 2 Extended and Part 3 Conformant, and meets the assurance requirements defined in
the Protection Profile for Application Software version 1.2, 22 April 2016 (PP_APP_v1.2).
The Target of Evaluation (TOE) identified in this Validation Report has been evaluated at a
NIAP approved Common Criteria Testing Laboratory using the Common Methodology for IT
Security Evaluation (Version 3.1, Rev. 5) for conformance to the Common Criteria for IT
Security Evaluation (Version 3.1, Rev. 5), as interpreted by the Assurance Activities contained in
the PP_APP. This Validation Report applies only to the specific version of the TOE as
evaluated. The evaluation has been conducted in accordance with the provisions of the NIAP
Common Criteria Evaluation and Validation Scheme and the conclusions of the testing
laboratory in the evaluation technical report are consistent with the evidence provided.
The validation team provided guidance on technical issues and evaluation processes and
reviewed the individual work units documented in the ETR and the Assurance Activities Report
(AAR). The validation team found that the evaluation showed that the product satisfies all of the
functional requirements and assurance requirements stated in the Security Target (ST). Based on
these findings, the validation team concludes that the testing laboratory's findings are accurate,
the conclusions justified, and the conformance results are correct. The conclusions of the testing
laboratory in the evaluation technical report are consistent with the evidence produced.
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2 Identification
The CCEVS is a joint National Security Agency (NSA) and National Institute of
Standards effort to establish commercial facilities to perform trusted product evaluations.
Under this program, security evaluations are conducted by commercial testing
laboratories called Common Criteria Testing Laboratories (CCTLs). CCTLs evaluate
products against Protection Profiles containing Assurance Activities, which are
interpretation of CEM work units specific to the technology described by the PP.
The NIAP Validation Body assigns Validators to monitor the CCTLs to ensure quality
and consistency across evaluations. Developers of information technology products
desiring a security evaluation contract with a CCTL and pay a fee for their product's
evaluation. Upon successful completion of the evaluation, the product is added to NIAP's
Product Compliance List.
Table 1 provides information needed to completely identify the product, including:
 The Target of Evaluation (TOE): the fully qualified identifier of the product as
evaluated.
 The Security Target (ST), describing the security features, claims, and assurances
of the product.
 The conformance result of the evaluation.
 The Protection Profile(s) to which the product is conformant.
 The organizations and individuals participating in the evaluation.
Table 1: Evaluation Identifiers
Item Identifier
Evaluation Scheme United States NIAP Common Criteria Evaluation and Validation Scheme
TOE Nubo Software Thin Client v2.0
Protection Profile Protection Profile for Application Software (PP_APP_v1.2)
Security Target Nubo Software Thin Client v2.0 Security Target, July 2018
Evaluation Technical
Report
Nubo Software Thin Client v2.0 ETR, July 2018
CC Version Version 3.1 Revision 5
Conformance Result CC Part 2 Extended and CC Part 3 Conformant
Sponsor Nubo Software
Developer Nubo Software
Common Criteria
Testing Lab (CCTL)
Acumen Security
2400 Research Blvd Suite 395,
Rockville, MD 20850
CCEVS Validators Linda Morrison, MITRE Corporation
Brad O’Neill, MITRE Corporation
Daniel Faigin, Aerospace Corporation
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3 Architectural Information
The TOE (Nubo Software Thin Client v2.0) is classified as a thin client executing on mobile
devices that provides the user interface to virtual mobile applications executing on Nubo
Software’s VMI servers. The TOE runs on evaluated Samsung Galaxy S7 and S7 Edge devices
running Android 6.0.1. The TOE is an application from the Google Play store installed and
executing on a mobile device. Thus, the TOE is considered to be a thin client, Virtual Mobile
Infrastructure (VMI) and Application Software as defined in PP_APP v1.2 modified by a few
Technical Decisions (TDs), which can be found in Table 1 of the Security Target.
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4 Security Policy
The logical boundary of the TOE includes those security functions implemented exclusively by
the TOE.
Cryptographic Operations
The TOE relies on underlying cryptographic functionality provided by the platform for all of its
cryptographic operations. In the evaluated configuration the TOE will be running on the
following CC validated platforms such as Samsung Galaxy S7 and S7 Edge (VID10739).
User Data Protection
The TOE does not store sensitive data in local files. The TOE can access physical resources on
the mobile device, but does not access any of the logical data repositories.
Identification and Authentication
The TOE utilizes underlying Android functionality to authenticate certificates for the
Management Server and Gateway.
Security Management
The TOE does not come with any default credentials, and no user credentials are stored by the
TOE.
Protection of the TSF
The TOE implements anti-exploitation measures to protect against compromise during
execution. The Android platform also provides protection for the TOE. Secure delivery of the
TOE is accomplish through delivery via the Google Play store
Privacy
The TOE requests PII including, first and last name when creating a new Nubo account. A
warning is displayed on the page indicating that this information will be transferred over the
network. The user may additionally supply PII when interacting with applications in the Nubo
VMI, but the TOE simply transparently transmits this data and is unaware of the nature of the
data.
Trusted Path/Channels
The TOE establishes trusted channels using HTTPS/TLS to the Management Server and
Gateway.
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5 Assumptions, Threats & Clarification of Scope
5.1 Assumptions
The specific conditions listed in the following subsections are assumed to exist in the TOE’s
environment. These assumptions include both practical realities in the development of the TOE
security requirements and the essential environmental conditions on the use of the TOE.
Assumption Description
A.PLATFORM The TOE relies upon a trustworthy computing platform for its execution. This
includes the underlying platform and whatever runtime environment it provides
to the TOE.
A.PROPER_USER The user of the application software is not willfully negligent or hostile, and
uses the software in compliance with the applied enterprise security policy.
A.PROPER_ADMIN The administrator of the application software is not careless, willfully negligent
or hostile, and administers the software within compliance of the applied
enterprise security policy.
5.2 Threats
The following table lists the threats addressed by the TOE and the IT Environment. The
assumed level of expertise of the attacker for all the threats identified below is Enhanced-Basic.
Threat Description
T.NETWORK_ATTACK An attacker is positioned on a communications channel or elsewhere on the
network infrastructure. Attackers may engage in communications with the
application software or alter communications between the application software
and other endpoints in order to compromise it.
T.NETWORK_EAVESDROP An attacker is positioned on a communications channel or elsewhere on the
network infrastructure. Attackers may monitor and gain access to data
exchanged between the application and other endpoints.
T.LOCAL_ATTACK An attacker can act through unprivileged software on the same computing
platform on which the application executes. Attackers may provide maliciously
formatted input to the application in the form of files or other local
communications.
T.PHYSICAL_ACCESS An attacker may try to access sensitive data at rest.
5.3 Clarification of Scope
All evaluations (and all products) have limitations, as well as potential misconceptions that need
clarifying. This text covers some of the more important limitations and clarifications of this
evaluation. Note that:
 As with any evaluation, this evaluation only shows that the evaluated configuration meets
the security claims made, with a certain level of assurance. The level of assurance for this
evaluation is defined within the PP_APP.
 Consistent with the expectations of the Protection Profile, this evaluation did not
specifically search for, nor seriously attempt to counter, vulnerabilities that were not
“obvious” or vulnerabilities to objectives not claimed in the ST. The CEM defines an
“obvious” vulnerability as one that is easily exploited with a minimum of understanding
of the TOE, technical sophistication and resources.
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 The evaluation of security functionality of the product was limited to the functionality
specified in the claimed PP. Any additional security related functional capabilities
included in the product were not covered by this evaluation.
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6 Documentation
The following documents were provided by the vendor with the TOE for evaluation:
 Nubo Software Thin Client v2.0 Security Target V 1.4
 Nubo Software Thin Client Thin Client Common Criteria Addendum V1.2
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7 TOE Evaluated Configuration
7.1 Evaluated Configuration
The TOE (Nubo Software Thin Client v2.0) is classified as a thin client executing on mobile
devices that provides the user interface to virtual mobile applications executing on Nubo
Software’s VMI servers. The TOE runs on evaluated Samsung Galaxy S7 and S7 Edge devices
running Android 6.0.1. The TOE is an application from the Google Play store installed and
executing on a mobile device. Thus, the TOE is considered to be a thin client, Virtual Mobile
Infrastructure (VMI) and Application Software as defined in PP_APP v1.2 modified by a few
TDs.
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8 IT Product Testing
This section describes the testing efforts of the developer and the evaluation team. It is derived
from information contained in Evaluation Test Report for Nubo Software Thin Client, which is
not publically available. The Assurance Activities Report provides an overview of testing and the
prescribed assurance activities.
8.1 Developer Testing
No evidence of developer testing is required in the Assurance Activities for this product.
8.2 Evaluation Team Independent Testing
The evaluation team verified the product according to the vendor-provided guidance
documentation and ran the tests specified in the PP_APP. The Independent Testing activity is
documented in the Assurance Activities Report, which is publically available, and is not
duplicated here.
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9 Results of the Evaluation
The results of the assurance requirements are generally described in this section and are
presented in detail in the proprietary documents: the Detailed Test Report (DTR) and the
Evaluation Technical Report (ETR). The reader of this document can assume that activities and
work units received a passing verdict.
A verdict for an assurance component is determined by the resulting verdicts assigned to the
corresponding evaluator action elements. The evaluation was conducted based upon CC version
3.1 rev 5 and CEM version 3.1 rev 5. The evaluation determined the Nubo Software Thin Client
to be Part 2 extended, and meets the SARs contained in the PP. Additionally the evaluator
performed the Assurance Activities specified in the PP_APP.
9.1 Evaluation of Security Target
The evaluation team applied each ASE CEM work unit. The ST evaluation ensured the ST
contains a description of the environment in terms of policies and assumptions, a statement of
security requirements claimed to be met by the Nubo Software Thin Client that are consistent
with the Common Criteria, and product security function descriptions that support the
requirements. Additionally the evaluator performed an assessment of the Assurance Activities
specified in the PP_APP.
The validator reviewed the work of the evaluation team, and found that sufficient evidence and
justification was provided by the evaluation team to confirm that the evaluation was conducted in
accordance with the requirements of the CEM, and that the conclusion reached by the evaluation
team was justified.
9.2 Evaluation of Development Documentation
The evaluation team applied each ADV CEM work unit. The evaluation team assessed the
design documentation and found it adequate to aid in understanding how the TSF provides the
security functions. The design documentation consists of a functional specification contained in
the Security Target's TOE Summary Specification. Additionally the evaluator performed the
Assurance Activities specified in the PP_APP related to the examination of the information
contained in the TOE Summary Specification.
The validator reviewed the work of the evaluation team, and found that sufficient evidence and
justification was provided by the evaluation team to confirm that the evaluation was conducted
in accordance with the Assurance Activities, and that the conclusion reached by the evaluation
team was justified.
9.3 Evaluation of Guidance Documents
The evaluation team applied each AGD CEM work unit. The evaluation team ensured the
adequacy of the user guidance in describing how to use the operational TOE. Additionally, the
evaluation team ensured the adequacy of the administrator guidance in describing how to
securely administer the TOE. The guides were assessed during the design and testing phases of
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the evaluation to ensure they were complete. Additionally the evaluator performed the Assurance
Activities specified in the PP_APP related to the examination of the information contained in the
operational guidance documents.
The validator reviewed the work of the evaluation team, and found that sufficient evidence and
justification was provided by the evaluation team to confirm that the evaluation was
conducted in accordance with the Assurance Activities, and that the conclusion reached by
the evaluation team was justified.
9.4 Evaluation of Life Cycle Support Activities
The evaluation team applied each ALC CEM work unit. The evaluation team found
that the TOE was identified.
The validator reviewed the work of the evaluation team, and found that sufficient evidence and
justification was provided by the evaluation team to confirm that the evaluation was conducted in
accordance with the requirements of the CEM, and that the conclusion reached by the evaluation
team was justified.
9.5 Evaluation of Test Documentation and the Test Activity
The evaluation team applied each ATE CEM work unit. The evaluation team ran the set of tests
specified by the Assurance Activities in the PP_APP and recorded the results in a Test Report,
summarized in the Evaluation Technical Report and Assurance Activities Report.
The validator reviewed the work of the evaluation team, and found that sufficient evidence was
provided by the evaluation team to show that the evaluation activities addressed the test activities
in the PP_APP, and that the conclusion reached by the evaluation team was justified.
9.6 Vulnerability Assessment Activity
The evaluation team applied each AVA CEM work unit. The evaluation team performed a public
search for vulnerabilities, performed vulnerability testing and did not discover any issues.
The validator reviewed the work of the evaluation team, and found that sufficient evidence and
justification was provided by the evaluation team to confirm that the evaluation addressed the
vulnerability analysis Assurance Activities in the PP_APP, and that the conclusion reached by
the evaluation team was justified.
9.7 Summary of Evaluation Results
The evaluation team's assessment of the evaluation evidence demonstrates that the claims in
the ST are met. Additionally, the evaluation team's test activities also demonstrated the
accuracy of the claims in the ST.
The validation team's assessment of the evidence provided by the evaluation team is that it
demonstrates that the evaluation team performed the Assurance Activities in the PP_APP, and
correctly verified that the product meets the claims in the ST.
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10 Validator Comments & Recommendations
The validation team notes that the evaluated configuration is dependent upon the TOE being
configured per the evaluated configuration instructions in the Nubo Software Thin Client Thin
Client Common Criteria Addendum V1.2.
Please note that the functionality evaluated is scoped exclusively to the security functional
requirements specified in the Security Target. Other functionality included in the product was not
assessed as part of this evaluation. All other functionality provided by the product needs to be
assessed separately and no further conclusions can be drawn about their effectiveness.
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11 Annexes
Not applicable.
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12 Security Target
Nubo Software Thin Client v2.0 Security Target, Version 1.4, July 2018.
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13 Glossary
The following definitions are used throughout this document:
 Common Criteria Testing Laboratory (CCTL). An IT security evaluation facility
accredited by the National Voluntary Laboratory Accreditation Program (NVLAP) and
approved by the CCEVS Validation Body to conduct Common Criteria-based
evaluations.
 Conformance. The ability to demonstrate in an unambiguous way that a given
implementation is correct with respect to the formal model.
 Evaluation. The assessment of an IT product against the Common Criteria using the
Common Criteria Evaluation Methodology to determine whether or not the claims made
are justified; or the assessment of a protection profile against the Common Criteria using
the Common Evaluation Methodology to determine if the Profile is complete, consistent,
technically sound and hence suitable for use as a statement of requirements for one or
more TOEs that may be evaluated.
 Evaluation Evidence. Any tangible resource (information) required from the sponsor or
developer by the evaluator to perform one or more evaluation activities.
 Feature. Part of a product that is either included with the product or can be ordered
separately.
 Target of Evaluation (TOE). A group of IT products configured as an IT system, or an
IT product, and associated documentation that is the subject of a security evaluation
under the CC.
 Validation. The process carried out by the CCEVS Validation Body leading to the issue
of a Common Criteria certificate.
 Validation Body. A governmental organization responsible for carrying out validation
and for overseeing the day-to-day operation of the NIAP Common Criteria Evaluation
and Validation Scheme.
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14 Bibliography
The Validation Team used the following documents to produce this Validation Report:
1. Common Criteria for Information Technology Security Evaluation - Part 1: Introduction
and general model, Version 3.1 Revision 5, April 2017.
2. Common Criteria for Information Technology Security Evaluation - Part 2: Security
functional requirements, Version 3.1 Revision 5, April 2017.
3. Common Criteria for Information Technology Security Evaluation - Part 3: Security
assurance requirements, Version 3.1 Revision 5, April 2017.
4. Common Evaluation Methodology for Information Technology Security Evaluation,
Version 3.1 Revision 5, April 2017.
5. Protection Profile for Application Software, Version 1.2, April 2016.
6. Nubo Software Thin Client Version 2.0 Security Target, Version 1.4, July 2018.
7. Nubo Software Thin Client Common Criteria Addendum, Version 1.2.
8. Nubo Software Thing Client V2.0 Evaluation Technical Report, Version 1.5, July 2018.
9. Common Criteria NDcPP Assurance Activity Report Nubo Software Thin Client V2.0,
Version .6, July 2018.