INTRODUCTION
In the
United States, government and industry have become dependent upon
telecommunications networks to support commerce in all of the major economic
sectors. At the same time, because of changes in technology, regulations,
customer service demands, and accelerated technology deployments to address
market pressures, the Public Switched Network (PSN) is becoming more vulnerable
to security breaches.
Several
reports have discussed recent intrusion experiences and potential threats to
the PSN. The National Research Council report, "Growing Vulnerability
of the Public Switched Network: Implications for National Security Emergency
Preparedness" [1], and the "Report of the Network Security
Task Force" [2], both address growing concern with possible network
disruptions. A more recent study, "The Electronic Intrusion Threat To
National Security and Emergency Preparedness (NS/EP) Telecommunications"
[18] reports that the network intruder's knowledge and sophistication is
increasing and the potential impact on the PSN is greater. Adequate protection
of PSN resources is required to ensure: the availability of service during
emergencies; the integrity of transmitted information; the non-disclosure of
sensitive information; and the prevention of service fraud.
This
chapter describes the scope of the threat, sources for these threats and
characteristics associated with the major categories of threats.
SCOPE OF
SECURITY THREATS
Changes
in network architectures, technologies, interfaces, services, and operations
may impact the ability of the PSN to provide the mix of functions and services
to meet NS/EP and commercial needs. "Threats" are accidental
or deliberate actions or events that compromise the quality, utility, or
functionality of network services and operations. Threats can result in
financial losses for the network and service providers and/or their users. A
"security threat" is an intentional threat, whether mischievous or
malicious, against network services and operations. The focus of this document
is security threats.
Threats
to the PSN could result in any of the following impacts:
1.
Service denial or disruption - Typically, service disruptions caused by
intruders have been brought about by accidental actions rather than malicious
attempts.
2.
Unauthorized monitoring and disclosure of sensitive information - The current
approaches that intruders have used are eavesdropping techniques, network
monitoring tools, and intrusions into network databases containing customer
information.
3.
Unauthorized modification of user or network information and network services -
Intruders have changed user service profiles and affected billing and routing.
This can result in unreliable service.
4. Fraud
- The typical approach is to build upon the previous attacks and masquerade as
a legitimate customer to commit fraud related to voice and data services.
SOURCES
OF THREATS
Threats8 to the PSN arise from several
different sources:
Source Likelihood Principal Impact on Network
Employees/Insiders 65% Availability,
integrity, privacy
Natural
disasters 20% Availability
Hackers 15% Availability,
integrity, privacy
EMPLOYEES/INSIDERS
Intentional
and accidental errors, omissions, and malicious acts by employees cause the
majority of the damages and losses experienced in the telecommunications
industry. This is partly attributable to changes in the definition of "employee."
Previously, an employee was usually considered a full-time member of an
organization. From a security perspective, it generally equated to an insider
with high privilege. Today, insiders also include contractors who have
administrative roles with respect to network service and may perform other job
functions as well. This broader definition of an employee increases the
potential of insider attacks that can severely impact the security of the PSN.
NATURAL
DISASTERS
Natural
disasters and accidents resulting from man-made causes can impact the
availability of the PSN. Disasters such as hurricanes, floods, fire, etc.,
impact the timeliness and quality of the delivered services. In addition to the
basic security concerns, NS/EP related capabilities can also be affected.
Methods of dealing with threats from natural and man-made disasters include the
use of redundant networks, reliable components, disaster recovery plans, and
priority restoration of services (e.g., The Telecommunications Service Priority
(TSP) System provides for priority provisioning and restoration of NS/EP
telecommunications services). A complete discussion of this topic is beyond the
scope of this document.
MALICIOUS
HACKERS
The PSN
is becoming increasingly controlled and dependent on software and operations
networks that may offer customer access to network functions, user-configured
databases, and special features. The potential for intruders to access network
management and operations functions is growing because customers now have greater
access to functions that were previously restricted to telecommunications
employees. This increases threats caused by viruses, worms, and other malicious
software. Dial-in access to PSN components is a prime point of malicious
intrusions into software-based telecommunications systems.
The
FCC-mandated ONA is designed to provide equal, user-transparent access via the
PSN to network services provided by network-based and non-network enhanced
service providers. ONA has the potential to create network vulnerabilities
because it greatly increases the number of users (some of whom may be hostile)
who have awareness of the network architecture. See NIST Special Publication
800-11 [22] for more information on the impact of ONA. In addition, as users
learn more about the operation of network software, those with hostile intent
will acquire knowledge that could assist them in misusing resources.
THREAT
CATEGORIES
Threats
are circumstances or events with the potential to cause harm to a system in the
form of destruction, disclosure, or modification of data and/or denial of
service. They have the potential to compromise the security of software
applications providing OAM&P functionality as well as network services.
They may be deliberate, e.g., hacking, or accidental, e.g. procedural errors.
The following is a list of categories of threats to software applications
residing on NE platforms:
1.
Masquerade - an attempt to gain unauthorized access to, or greater privilege to
a system, by posing as an authorized user (e.g., using stolen logon ids and
passwords). This may be done by replaying data or inserting false data that
appears genuine into a communications path. System software and data may be
deleted, disclosed, or corrupted. An example is the re-programming of NE
software to insert malicious code to steal passwords. This threat can occur
from:
a. Outside users accessing the NE from the public network;
b Locally
connected users;
c.
Compromised administrator accounts that are configured for direct and remote
access;
d.
Administrators dialing into dial-in modems connected to the NE.
2.
Disclosure of information - data disclosed without authorization, either by
deliberate action or by accident. Examples include:
a.
Eavesdropping on phone conversations or on data transmissions;
b.
Unauthorized disclosure of routing, address or other customer or service
related information;
c.
Deliberate misrouting data to enable an unauthorized entity to access
information.
3.
Message stream or data modification - data altered in some meaningful way by
reordering, deleting or modifying it. Examples include:
a.
Accessing and changing billing information;
b.
Unauthorized modification of NE software or databases;
c.
Rerouting calls.
4. Denial
of service - actions that prevent the NE from functioning in accordance with
its intended purpose. A piece of equipment or entity may be rendered inoperable
or forced to operate in a degraded state; operations that depend on timeliness
may be delayed. Examples include:
a.
Unauthorized destruction of existing NE resources including hardware, software,
and databases;
b.
Degraded NE service processing caused by a large volume of service requests;
c.
Putting a NE in an "out-of-service" state.
5. Traffic
analysis - a form of passive attack in which an intruder observes information
being transmitted and makes
inferences from the calling and called numbers, and the frequency and length of
the calls. Examples are:
a. An
intruder concludes that a high volume of communications between a company and
the Patent Office indicates that a patent is being filed;
b. A
corporate merger is deduced from the amount of traffic between two companies.
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