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

esources so that the required real-time interactions of that system with its legitimate peers are
detrimentally impacted?
A basic attribute of network environments is that risks to elements within that system increase in
direct relationship to the network’s population size. The larger the community of networked
devices, the greater the possibility that at least one of those devices has been constructed with
latent bugs that can be leveraged to compromise that device to directly or indirectly attack other
parts of the system. Also, the larger the community of humans that can access elements within
the total network system, the greater the possibility that at least one of those humans will exploit
bugs either intentionally (maliciously) or accidentally. Hostile electronic attacks may be
conducted by both the corrupted insider (e.g., insider threat) as well as by unauthorized
personnel who have leveraged system or process blemishes to gain unauthorized (remote) entry
into the system. It can also occur by means of accidental mistakes made by authorized
personnel.
Widely used COTS network equipment, such as Internet technologies, is more easily assembled
into large network systems than less popular communications technologies. For example, the
Aeronautical Telecommunications Network (ATN), which is used for air traffic management
systems today, is built using open system interconnect (OSI) protocols. OSI protocols are rarely
deployed today except within specialized niche environments. Because of this, it is
comparatively difficult to link ATN systems with other networks to create large network
communities. IP systems, by contrast, are ubiquitously deployed today. Because of this, it is
comparatively easy to link together IP-based systems with other networks to create large
network environments. A key point to recognize is that just because an IP-based system is not
connected to a large network environment today, does not mean that it cannot easily be
connected into a large networked environment tomorrow, perhaps inadvertently. For example,
inadvertent exposure of allegedly stand-alone (i.e., physically isolated via an air gap) IP
networks to remote Internet-based attacks have occurred many times in real life by means of
inadequately secured modems located within those allegedly isolated networks.
Widely deployed public networks have larger populations of users than small private networks.
The more people within the networking community, the greater the probability that one or more
of them may pose an attack risk to the elements within the system. The larger the cumulative
number of users within any aspect of the network, the greater the possibility is that a user may
purposefully or accidentally exploit those weaknesses in a detrimental manner.
The inclusion of the words “aspect of the network” in the previous sentence is a reference to a
technical point that is partially explained within appendix A. That point is that in large networkof-network
systems, such as the worldwide Internet, network access control defenses are
established between discrete network administrative entities by means of security firewalls [23].
Firewall technologies have significantly improved over time. Unfortunately, so has the
sophistication of attacks against them. A class of exploits 3 exist that may possibly circumvent
the access control protections of firewall systems. Should these attacks succeed, then those
attackers could access network systems where they are not authorized.
3 e.g., fragmentation attacks, time-based attacks, HTTP-based (Port 80) attacks, and other emerging exploits.
23