[Federal Register Volume 72, Number 248 (Friday, December 28, 2007)]
[Rules and Regulations]
[Pages 73582-73585]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-25075]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM365 Special Conditions No. 25-357-SC]


Special Conditions: Boeing Model 787-8 Airplane; Systems and Data 
Networks Security-Protection of Airplane Systems and Data Networks from 
Unauthorized External Access

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Model 787-8 
airplane. This airplane will have novel or unusual design features when 
compared to the state of technology envisioned in the airworthiness 
standards for transport category airplanes. The architecture of the 
Boeing Model 787-8 computer systems and networks may allow access to 
external systems and networks, such as wireless airline operations and 
maintenance systems, satellite communications, electronic mail, the 
Internet, etc. On-board wired and wireless devices may also have access 
to parts of the airplane's digital systems that provide flight critical 
functions. These new connectivity capabilities may result in security 
vulnerabilities to the airplane's critical systems. For these design 
features, the applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for protection and security of 
airplane systems and data networks against unauthorized access. These 
special conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing standards. Additional 
special conditions will be issued for other novel or unusual design 
features of the Boeing Model 787-8 airplanes.

DATES: Effective Date:
    January 28, 2008.

FOR FURTHER INFORMATION CONTACT: Will Struck, FAA, Airplane and Flight 
Crew Interface, ANM-111, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 227-2764; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Background

    On March 28, 2003, Boeing applied for an FAA type certificate for 
its new Boeing Model 787-8 passenger airplane. The Boeing Model 787-8 
airplane will be an all-new, two-engine jet transport airplane with a 
two-aisle cabin. The maximum takeoff weight will be 476,000 pounds, 
with a maximum passenger count of 381 passengers.

Type Certification Basis

    Under provisions of 14 Code of Federal Regulations (CFR) 21.17, 
Boeing must show that Boeing Model 787-8 airplanes (hereafter referred 
to as ``the 787'') meet the applicable provisions of 14 CFR part 25, as 
amended by Amendments 25-1 through 25-117, except Sec. Sec.  25.809(a) 
and 25.812, which will remain at Amendment 25-115. If the Administrator 
finds that the applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for the 787 because of a novel 
or unusual design feature, special conditions are prescribed under 
provisions of 14 CFR 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the 787 must comply with the fuel vent and exhaust emission 
requirements of 14 CFR part 34 and the noise certification requirements 
of part 36. The FAA must also issue a finding of regulatory adequacy 
pursuant to section 611 of Public Law 92-574, the ``Noise Control Act 
of 1972.''
    The FAA issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38, and they become part of the type certification basis under 
Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate

[[Page 73583]]

for that model be amended later to include any other model that 
incorporates the same or similar novel or unusual design feature, the 
special conditions would also apply to the other model under Sec.  
21.101.

Novel or Unusual Design Features

    The digital systems architecture for the 787 consists of several 
networks connected by electronics and embedded software. This proposed 
network architecture is used for a diverse set of functions, including 
the following.
    1. Flight-safety-related control and navigation and required 
systems (Aircraft Control Domain).
    2. Airline business and administrative support (Airline Information 
Domain).
    3. Passenger entertainment, information, and Internet services 
(Passenger Information and Entertainment Domain).
    The proposed architecture of the 787 is different from that of 
existing production (and retrofitted) airplanes. It may allow 
connection to and access from external sources and airline operator 
networks to the previously isolated Aircraft Control Domain and Airline 
Information Domain. Types of connections and access from external 
sources may include wireless systems, satellite communications, 
electronic mail, the Internet, etc. The Aircraft Control Domain and the 
Airline Information Domain perform functions required for the safe 
operation of the airplane.
    Capability is proposed for providing electronic transmission of 
field-loadable software applications and databases to the aircraft. 
These would subsequently be loaded into systems within the Aircraft 
Control Domain and Airline Information Domain. Also, it may be proposed 
that on-board wired and wireless devices have access to the Aircraft 
Control Domain and Airline Information Domain. These new connectivity 
capabilities and features of the proposed design may result in security 
vulnerabilities from intentional or unintentional corruption of data 
and systems critical to the safety and maintenance of the airplane. 
Existing regulations and guidance material did not anticipate this type 
of system architecture or Internet and wireless electronic access to 
aircraft systems that provide flight critical functions. Furthermore, 
14 CFR regulations and current system safety assessment policy and 
techniques do not address potential security vulnerabilities that could 
be caused by unauthorized external access to aircraft data buses and 
servers. Therefore, special conditions are proposed to ensure the 
security, integrity, and availability of the critical systems within 
the Aircraft Control Domain and the Airline Information Domain by 
establishing requirements for:
    1. Protection of Aircraft Control Domain and Airline Information 
Domain systems, hardware, software, and databases from unauthorized 
access.
    2. Protection of field-loadable software (FLS) applications and 
databases that are electronically transmitted from external sources to 
the on-aircraft networks and storage devices, and used within the 
Aircraft Control Domain and Airline Information Domain.
    3. Test and evaluation of security protection means and change 
control procedures of aircraft systems, hardware, software, and 
databases, especially for critical systems and those areas that could 
affect safety of flight.

Discussion Of Comments

    Notice of Proposed Special Conditions No. 25-07-02-SC for the 787 
was published in the Federal Register on April 16, 2007 (72 FR 18923). 
Several comments were received from Airbus.
     AIRBUS General Comment 1: In Airbus's opinion these 
special conditions leave too much room for interpretation, and related 
guidance and acceptable means of compliance should be developed in an 
advisory circular (AC) for use by future applicants.
    FAA Response: We agree that guidance is necessary. Detailed 
guidelines and criteria have been developed for this aircraft 
certification program, specific to this airplane's network architecture 
and design, providing initial guidance on an acceptable means of 
compliance for the 787. Additionally, the FAA intends to participate in 
an industry committee chartered with developing acceptable means of 
compliance to address aircraft network security issues, and hopes to 
endorse the results of the work of that committee by issuing an AC. 
Until such time as guidance is developed for a general means of 
compliance for network security protection, these special conditions 
and the agreed-to guidance are imposed on this specific network 
architecture and design. We have made no changes to these special 
conditions as a result of this comment.
     AIRBUS Comment (a): Airbus said that the meaning of 
``shall ensure system security protection * * * from unauthorized 
external access'' in the first sentence is not accurate enough. Airbus 
commented that this could be interpreted as a zero allowance and 
demonstrating compliance with such a requirement all through the 
aircraft's life cycle is quite impossible since security threats evolve 
very rapidly. The commenter maintained that the only possible solution 
to such a requirement would be no link and no communication at all 
between the aircraft and the outside world. Airbus asked, ``if some 
residual vulnerabilities are allowed, which criteria have to be used to 
assess their acceptability?''
    FAA Response: The applicant is responsible for the design of the 
airplane network and systems architecture and for ensuring that 
potential security vulnerabilities of providing external access to 
airplane networks and systems are mitigated to an appropriate level of 
assurance, depending on the potential risk to the airplane and occupant 
safety. This responsibility is similar to that entailed in the current 
system safety assessment process of 14 CFR 25.1309. (See also AC 
25.1309-1A and the ARAC-recommended Arsenal version of this AC, at 
http://www.faa.gov/regulations_policies/rulemaking/committees/arac/media/tae/TAE_SDA_T2.pdf and SAE ARP 4754). These special conditions 
do not prescribe a specific level of assurance because assurance levels 
are dependent on the aircraft network architecture, specific external 
access points allowed, potential threats and vulnerabilities of each 
access, and various means of mitigating those vulnerabilities, whether 
by aircraft and network design features, monitoring features, 
operational procedures, maintenance procedures, and/or combinations 
thereof. Detailed compliance guidelines and criteria, specific to the 
787 network architecture and design, have been developed to provide 
initial guidance for an acceptable means of compliance for this 
aircraft model. Residual vulnerabilities may have to be assessed on a 
case-by-case basis to ascertain whether sufficient and acceptable 
mitigation is provided. As mentioned earlier, the FAA intends to 
participate in an industry forum chartered with determining appropriate 
criteria and acceptable means of compliance, and hopes to endorse that 
guidance with an AC. We have made no changes to these special 
conditions as a result of this comment.
     AIRBUS Comment (b): Airbus commented that external access 
can be interpreted in two ways: external to the aircraft, or external 
to the Aircraft Control Domain and Airline Information Domain. It said 
that the Passenger Information and Entertainment Domain (PIED) may be 
considered external and,

[[Page 73584]]

if it is, this special condition is redundant to Proposed Special 
Condition 25-07-01-SC.
    FAA Response: Since these special conditions are applicable to the 
787 aircraft, the interpretation of ``external'' means external to the 
787 aircraft. Although the PIED is external to the other domains 
mentioned, it is ``internal'' to the aircraft. Special Condition 25-07-
01-SC was developed to address interfaces between the PIED and the 
Aircraft Control and Airline Information Domains, and is therefore not 
redundant. We have made a minor change to these special conditions as a 
result of this comment. We have reworded the special conditions, 
changing the words ``unauthorized external access'' to ``access by 
unauthorized sources external to the airplane'' in order to clarify 
this point.
     AIRBUS Comment (c): Airbus commented that the term 
``unauthorized external access'' is too vague and could be interpreted 
in too restrictive a way, resulting in too few threats being 
considered. The commenter asked whether unauthorized external access 
encompasses physical access or unauthorized access by an authorized 
user and/or an unauthorized user. The commenter asked whether physical 
tampering has to be considered. Airbus suggested that any threats 
external to the aircraft be considered, and that we refer as well to 
the list of threats in the National Airspace System Communication 
System Safety Hazard Analysis and Security Threat Analysis.
    FAA Response: The applicant is responsible for the aircraft network 
architecture and design, and for implementing security protection 
mechanisms and controls. Examples include:
     defining authorized versus unauthorized users,
     user authentication,
     defining the scope of authorized users' access to various 
components connected to the airplane networks,
     ensuring correct software loads are stored on 
appropriately secured servers, are loaded into the correct systems, are 
compatible with other loads, etc.; and
     defining the maintenance requirements for ensuring 
continued operational safety of the aircraft.

Operators and maintainers are responsible for performing maintenance 
procedures in compliance with those requirements. For maintenance 
tasks, however, it may be appropriate to provide some level of security 
protection for mechanics to ensure they are authorized for specific 
tasks within certain domains or systems of the aircraft for performing 
repairs or loading software updates, which would typically require 
``physical access.'' With current wireless technology, actual physical 
access may not be necessary to perform some maintenance functions. The 
applicant is responsible for developing a design which complies with 
these special conditions and other applicable regulations. The design 
may include specific technology and architecture features as well as 
operator requirements, operational procedures and security measures, 
and maintenance procedures and requirements to ensure an appropriate 
implementation that can be properly used and maintained to ensure safe 
operations and continued operational safety. Applicants should define 
all external accesses and the scope of their aircraft network security 
protections. Use of the threats listed in the above-mentioned document 
may be appropriate for these purposes. We have made no changes to these 
special conditions as a result of this comment.
     AIRBUS Comment (d): Airbus said that the external 
environment needs to be characterized in order to determine which 
threats the Aircraft Control Domain and Airline Information Domain must 
be protected from. Questions to be answered include who can and cannot 
access; who is and is not trusted; and what threat source profile must 
be considered. The commenter asked whether only new communication media 
(like internet protocol (IP) communications) would be considered not 
trusted, or whether all communications, including existing 
communications for which no security requirements have been applied up 
to now, would be considered not trusted. Airbus gave ACARS (the 
Aeronautical Radio Incorporated Communication Addressing and Reporting 
System) as an example of existing communications that currently have no 
security requirements.
    FAA Response: Each access (or communication) from an external 
source and its potential vulnerabilities to threats should be 
evaluated. The security mitigation should provide protection to an 
appropriate level, whether by design, monitoring, operational 
procedures, or other means. The security solution could certainly 
consider access rights and scope, trusted versus not trusted sources 
and data, how reliable incoming communication data may be, and other 
factors, depending on the intended use and potential for presenting a 
security risk. We have made no changes to these special conditions as a 
result of this comment.
     AIRBUS Comment (e): Airbus said that the characterization 
of the external environment must be extended to the maintenance 
organization, because the security objectives of these special 
conditions must consider maintenance activity. Proposed condition 1 
requires minimizing the likelihood of reductions in safety margins or 
airplane functional capabilities, ``* * * including those possibly 
caused by maintenance activity''. Airbus said that the trust level for 
the maintenance organization, to be defined, may significantly impact 
the design of the on-board security protections and the compliance 
demonstration.
    FAA Response: The proposed special conditions include the potential 
for security risks from maintenance activities. Applicants should 
develop a design and maintenance procedures which facilitate routine 
maintenance of the aircraft, networks and systems, and equipment. The 
design and maintenance procedures should also provide capabilities for 
ensuring that security features and updates can be maintained by the 
operators and maintenance personnel, to ensure continued airworthiness 
and operational safety of the aircraft for its service life. These are 
methods of compliance issues, and therefore we have made no changes to 
these special conditions as a result of this comment.
     AIRBUS Comment (f): Airbus referred to wording in the 
second sentence of the proposed special condition : ``* * * to minimize 
the likelihood of occurrence of each of the following conditions: * * * 
'' Airbus noted that the definition of likelihood of occurrence and the 
criteria for fulfilling the security objectives are missing. The 
commenter asked, ``when is an identified risk considered mitigated?'' 
Airbus also noted that the 3 conditions at the end of the special 
conditions are quite similar to the description of safety severity 
effects for a ``Failure Condition classified Major'' per AC 25.1309-1A 
(or AC/AMJ No: 25.1309). Airbus maintained that, as a result, this 
description can be interpreted as an allowable qualitative likelihood 
of occurrence corresponding to ``remote'' and an allowable quantitative 
probability corresponding to less than 10E-5. Airbus said that such a 
classification, if interpreted in this way, may be irrelevant in some 
cases, because consequences may be more severe, and only a security 
threat analysis process can conclude which safety effect is acceptable. 
The commenter said that recognizing this process as an acceptable means 
of compliance (through an AC) could

[[Page 73585]]

remove any dispute about how to assess the severity and likelihood of 
occurrence of a threat over which the applicant has no control.
    FAA Response: We agree that a ``security threat analysis process'' 
(or other acceptable means) should be conducted to determine the 
threats, vulnerabilities, and risks of each airplane network access 
from an external source to determine appropriate security mitigation 
protection and procedures for the aircraft, its operations, and 
maintenance. The aircraft and system safety assessments (as described 
in AC 25.1309) should certainly consider the impact of security 
vulnerabilities on aircraft safety and the capabilities of the 
aircraft's systems to satisfy reliability and integrity requirements. 
Detailed guidelines and criteria, specific to the 787 network 
architecture and design, have been developed for this aircraft and 
provide some initial guidance for an acceptable means of compliance. 
The FAA also intends to participate in industry efforts to develop 
additional guidance on the scope of security assessments and a general 
means of addressing aircraft network security concerns. We hope to 
endorse the industry-developed guidance, when it has been completed, 
with an advisory circular. We have made some minor changes to these 
special conditions as a result of this comment to clarify the scope for 
security threat analysis.
     AIRBUS proposed text revision: Airbus proposed the 
following revised wording for these special conditions.
    The applicant shall ensure that security threats external to the 
aircraft (including those possibly caused by maintenance activity) are 
assessed and risk mitigation strategies are implemented to protect the 
Aircraft Control Domain and Airline Information Services Domain from 
adverse impacts reducing the aircraft safety.
    FAA Response: Airbus's comments and proposal have merit but the 
proposal does not address all of the FAA concerns. We have, however, 
adopted several aspects of the commenter's proposal into these final 
special conditions. We have made these wording changes for 
clarification, but the meaning and intent of these special conditions 
remain the same as originally proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
787. Should Boeing apply at a later date for a change to the type 
certificate to include another model on the same type certificate 
incorporating the same novel or unusual design features, these special 
conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
of the 787. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for the Boeing Model 787-8 airplane.

    The applicant shall ensure system security protection for the 
Aircraft Control Domain and Airline Information Domain from access 
by unauthorized sources external to the airplane, including those 
possibly caused by maintenance activity. The applicant shall ensure 
that security threats are identified and assessed, and that risk 
mitigation strategies are implemented to protect the airplane from 
all adverse impacts on safety, functionality, and continued 
airworthiness.

    Issued in Renton, Washington, on December 17, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-25075 Filed 12-27-07; 8:45 am]
BILLING CODE 4910-13-P