Local Area Networks (LANs) in Aircraft - FTP Directory Listing - FAA

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EXECUTIVE SUMMARY This is the final report of a 2-year Federal Aviation Administration (FAA)-funded study to address security and safety issues associated with networked airborne local area networks. This study consisted of two phases. Phase 1 investigated the methodologies for identifying and mitigating potential security risks of onboard networks that could impact safety. Phase 2 investigated techniques for mitigating security risks in the certification environment. Current FAA safety assurance processes for airborne systems are based on Aerospace Recommended Practice (ARP) 4754, ARP 4761, and Advisory Circulars (AC) (e.g., AC 25.1309-1A and AC 23.1309-1C). FAA software assurance is based on compliance with DO-178B that guides software development processes. Complex electronic hardware design assurance is based on RTCA/DO-254. ARP 4754 extends the DO-178B software assurance process to address the additional safety issues that arise when software is embedded into highly integrated or complex airborne system relationships. Connecting airborne software within network systems represents an extension of the ARP 4754 environment to networked items that share limited common functional relationships with each other. This is because networks connect entities or components of a system into a common networked system regardless of the original functional intent of the system design (e.g., multiple aircraft domains can be connected by a common network system). Networks are inherently hostile environments because every network user, including both devices (and their software) and humans, is a potential threat to that environment. Networked entities form a fate-sharing relationship with each other because any compromised network entity can theoretically be used to attack other networked entities or their shared network environment. Networked environments and the entities that comprise them need to be protected from three specific classes of threat agents: (1) the corrupted or careless insider, (2) the hostile outsider, and (3) client-side attacks. Because of these dangers, ARP 4754 needs to be extended for networked environments by ensuring network security protection and function/component availability and integrity. This, in turn, implies the need to strategically deploy information assurance security controls within network airborne systems. Safety and security have therefore become intertwined concepts within networked airborne environments. Security engineering addresses the potential for failure of security controls caused by malicious actions or other means. Safety analysis focuses on the effects of failure modes. The two concepts (safety and security) are therefore directly related through failure effects. A shortcoming of either a safety process or a security process may cause a failure in a respective system safety or security mechanism, with possible safety consequences to the aircraft, depending on the specific consequence of that failure. Previous studies have sought to address airborne safety and security by correlating DO-178B safety processes with common criteria security processes. This correlation produces necessary but inadequate results. It is inadequate because it lacks mathematical rigor and, therefore, produces ad hoc conclusions. The results are ad hoc because, even when safety and security are correlated, they are nevertheless distinct concepts from each other, addressing very different concerns. xiii
This report states that the primary issue impacting network airborne system safety is how to extend existing ARP 4574, ARP 4761, DO-178B, and DO-254 assurance guidance processes into networked systems and environments in a mathematically viable manner. This study recommends that these processes can be extended into arbitrarily vast network environments in a mathematically viable manner by using the Biba Integrity Model framework. This report maps current DO-178B and ARP 4754 processes into the Biba Integrity Model framework using wellestablished system security engineering processes to define airborne safety requirements. It applies best current information assurance techniques upon those airborne safety requirements to create a generic airborne network architecture. Since the Biba Integrity Model is an integrity framework, it carries within itself a natural mechanism for relating safety and security concepts in terms of their respective integrity attributes. Nevertheless, this study recommends that the model be implemented solely within the context of existing FAA safety processes. This results in airborne network systems being organized into networks that operate at specific safety levels (the DO-178B software levels). There are fortuitous secondary effects from using the Biba Integrity Model to extend current FAA processes into networked environments that stem from it being the direct analog of the Bell-LaPadula Confidentiality Model. The Bell-LaPadula Confidentiality Model forms the framework for confidentiality within U.S. Department of Defense (DoD) information processing. Consequently, the application of the Biba Integrity Model to airborne system assurance processes results in an airborne network architecture that remarkably resembles the emerging DoD network architecture (the global information grid (GIG)), despite their very different underlying goals. Consequently, the generic airborne network architecture identified by this study greatly resembles the DoD’s GIG architecture. While military technologies could be used to implement the airborne network architecture, this study recommends the use of civilian Internet protocols deployed as a virtual private network. In addition, the similarities between the Biba Integrity Model and the Bell-LaPadula Confidentiality Models may result in increased synergies between the DoD and FAA certification processes. Deploying airborne systems into networked environments means that the FAA system safety assessment (ARP 4761), system development (ARP 4754), software assurance (DO-178B), and complex electronic hardware assurance (DO-254) processes need to be extended to address and mitigate network threats. For example, although security is primarily a systems concept involving system issues (e.g., ARP 4754), the Biba Integrity Model relies upon the networked items having integrity attributes that function at a known assurance level (i.e., specific DO-178B software levels). This means that the processes for developing those items for network environments should be extended to address network attack risks. The concept of highassurance software in networked environments should therefore mean that items and systems will behave in the same manner before, during, and after network attacks; i.e., be immune to potential network-based threats. Exploits in network environments leverage latent software blemishes so that software items are subject to misbehavior, corruption, or compromise, possibly including xiv
Page 1 and 2: DOT/FAA/AR-08/31 Air Traffic Organi
Page 3 and 4: 1. Report No. DOT/FAA/AR-08/31 4. T
Page 5 and 6: 5.4.2 Aircraft as a Node (MIP and M
Page 7 and 8: 11.1 Findings and Recommendations 1
Page 9 and 10: 22 Customer’s L3VPN Protocol Stac
Page 11 and 12: LIST OF ACRONYMS AND ABBREVIATIONS
Page 13: PBN PC PE PEP PFS PIB PIM-DM PIM-SM
Page 17 and 18: 1. INTRODUCTION. This is the final
Page 19 and 20: protocol (IP)-based communications.
Page 21 and 22: of linking aircraft-resident system
Page 23 and 24: Industry and governments are extrem
Page 25 and 26: 2.1 NOTIONAL NETWORKED AIRCRAFT ARC
Page 27 and 28: Other Control Sites Controller ATC
Page 29 and 30: • The security viability of curre
Page 31 and 32: alternative requires that parallel
Page 33 and 34: Aircraft network security is a syst
Page 35 and 36: 4. NETWORK RISKS. This section spec
Page 37 and 38: General Threat Identifiers FAILURE
Page 39 and 40: esources so that the required real-
Page 41 and 42: “With the rise of client-side att
Page 43 and 44: • During an 11-month period (Apri
Page 45 and 46: attempt the theft of passwords. Non
Page 47 and 48: IP networks are organized in terms
Page 49 and 50: either the user or the trusted soft
Page 51 and 52: However, the previous paragraph beg
Page 53 and 54: Table 1. Internet Engineering Task
Page 59 and 60: • Lightweight directory access pr
Page 61 and 62: mechanism to overcome the key distr
Page 63 and 64: Deployments that need to support mu
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Today’s Reality: Islands of Commu
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Simultaneously, IP addresses are al
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in-depth manner. Defense-in-depth m
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Protection Detection Reaction / Neu
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encrypted and then encapsulated wit
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Internet (grouping of autonomous sy
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via that same IP address. Specifica
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deployments. Regional flights that
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neighbor as a next hop after “Hol
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Interface Interface Customer Site S
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Interface Customer’s Application
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Although the vast majority of PBN s
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6. RELATING SAFETY AND SECURITY FOR
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6.1.1 Integrity. As section 4.3 ind
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As mentioned in section 4.4, the hi
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6.1.4 Confidentiality. Confidential
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their own classification level nor
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integrity is not permitted to obser
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software has been confirmed as leve
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• Both safety and security are co
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Device at Safety level X Device at
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in a Biba Integrity Model environme
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Common Criteria Classes ACM—Confi
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(see section 9.10). A secure mechan
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employed in security-critical appli
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concept, which is needed to create
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4. Learn from past mistakes. Poor d
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exemplar airborne network architect
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• Requirement 8: Biba Integrity M
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Figure 31 shows how the recommended
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to-live (TTL) field in the IP heade
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using the traditional dual router i
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mechanism relies upon the controlle
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HAGs are high-assurance devices tha
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8.3.5 Firewall. The firewall needs
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(AJ) or low probability of intercep
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design decisions that need to be de
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9.2 INTEGRATED MODULAR AVIONICS IMP
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9.3 USING PUBLIC IPs. The model and
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alerted the pilots because the fail
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environments. If the certification
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DSS (FIPS 186 [81]). Code signing i
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elationship with other equipment in
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approach is to keep the log informa
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11. SUMMARY. Current civilian aircr
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environments should be extended to
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12. COTS computer systems cannot be
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14. NAS and airborne network archit
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22. If SWAP considerations permit,
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11.2 TOPICS NEEDING FURTHER STUDY.
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9. Lee, Y., Rachlin, E., and Scandu
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32. Loscocco, P., Smalley, S., Muck
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59. Raisinghani, V. and Sridhar, I.
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the following is a pointer to a rel
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Department of Defense Instruction N
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Information Assurance—The Departm
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Threat source—Either (1) intent a
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information found within these data
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(HTTP) traffic (port 80), port scan
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The simple network management proto
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opportunities to crack the hosting
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authorized to perform. 13 However,
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sniffers, log-cleaning scripts, and
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A.3.1 DENIAL OF SERVICE ATTACKS. Th
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• Disclosure: Disclosure of routi
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affected by the signal intermittenc
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A-15. Barbir, A., Murphy, S., and Y
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Survey Question What is the primary
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Survey Question What is the primary
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should be emphasized that there is
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