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

unless, of course, the firewall has established a reverse proxy that is equipped to handle this type
of threat. Attackers can similarly control what is happening on devices within the firewall by
communicating with the cracked device via HTTP (port 80), a protocol that is rarely blocked by
any firewall.
Routers have similar vulnerabilities to end-systems except that they are more likely than endsystems
to be identified by traceroute and they usually have substantially fewer resident
application daemons for the attacker to potentially exploit.
Attackers often attack routers through SNMP. There are many security problems with SNMP
(see section 4.6). These systems are particularly vulnerable if older versions of SNMP (i.e.,
SNMPv1 or SNMPv2) are being used or if the default SNMP community names have not been
altered or removed from the network device previous to deployment (e.g., “public,” “write,”
“user” are common default SNMP account names on routers, usually without any associated
password protections). Similar vulnerabilities exist for the default accounts and maintenance
accounts that come on most networking devices. In all other respects, the threats and exploits
affecting network devices such as routers are the same as those affecting computers, except that
the network devices traditionally have substantially fewer applications, and therefore less
vulnerability for attackers to exploit.
A.3 AVAILABILITY ATTACKS.
These attacks do not seek to take over devices or network systems, but rather seek to make the
network systems supporting devices become ineffectual.
A number of controls have been proposed to thwart specific classes of availability attacks. Some
of these controls have been demonstrated in laboratory environments. However, other than
securing the data communications protocols themselves (see section 4.5), few if any of these
mechanisms have yet been demonstrated to be effective within actual operational network
deployments. Thus, effective defenses against many classes of availability attacks are not yet
available within today’s best current practices.
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