DISCUSSION [NIST SP 800-171 R2]

VoIP has different requirements, features, functionality, availability, and service limitations when compared with the Plain Old Telephone Service (POTS) (i.e., the standard telephone service). In contrast, other telephone services are based on high-speed, digital communications lines, such as Integrated Services Digital Network (ISDN) and Fiber Distributed Data Interface (FDDI). The main distinctions between POTS and non-POTS services are speed and bandwidth. To address the threats associated with VoIP, usage restrictions and implementation guidelines are based on the potential for the VoIP technology to cause damage to the system if it is used maliciously. Threats to VoIP are similar to those inherent with any Internet-based application.

NIST SP 800-58 provides guidance on Voice Over IP Systems.

FURTHER DISCUSSION

Controlling VoIP technologies starts with establishing guidelines and enforcing the appropriate usage that is described in organizational policies. Monitoring should include the users’ activity for anything other than what is permitted and authorized and detection of insecure or unauthorized use of the VoIP technology. Security concerns for VoIP include eavesdropping on calls and using ID spoofing to impersonate trusted individuals.

Selecting a solution that can encrypt VoIP traffic is helpful in maintaining the confidentiality and integrity of the voice data.

Example

You are a system administrator responsible for the VoIP system. You configure VoIP for new users after being notified that they have signed the Acceptable Use Policy for VoIP technology [a]. You verify that the VoIP solution is configured to use encryption and have enabled requirements for passwords on voice mailboxes and on phone extension management. You require phone system administrators to log in using multifactor authentication when managing the system [a]. You add the VoIP software to the list of applications that are patched monthly as needed [a,b]. Finally, you configure the VoIP system to send logs to your log aggregator so that they can be correlated with those from other systems and examined for signs of suspicious activity [b].

Potential Considerations

Are VoIP technologies (e.g., approved and managed products or solutions) that may or may not be used in the system defined [a]?

Is monitoring for unapproved VoIP technologies or unapproved use of the allowed VoIP solutions employed [b]?

Copyright

Copyright 2020, 2021 Carnegie Mellon University and The Johns Hopkins University Applied Physics Laboratory LLC.

Copyright 2021 Futures, Inc.

This material is based upon work funded and supported by the Department of Defense under Contract No. FA8702-15-D-0002 with Carnegie Mellon University for the operation of the Software Engineering Institute, a federally funded research and development center, and under Contract No. HQ0034-13-D-0003 and Contract No. N00024-13-D-6400 with the Johns Hopkins University Applied Physics Laboratory LLC, a University Affiliated Research Center.

The view, opinions, and/or findings contained in this material are those of the author(s) and should not be construed as an official Government position, policy, or decision, unless designated by other documentation.

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