1. Henning Schulzrinne Columbia University
VoIP Security
Henning Schulzrinne
Columbia University
November 2006
VoIPSec

2. Overview Taxonomy General network threats made worse Resources
November 2006
VoIPSec

3. Services Call control Directory services Gateway service
call establishment, reporting, mid-call service features, and teardown  SIP, proxies
Directory services
alias, user name, extension, E.164 number  URL (ENUM)
Gateway service
inter-work between two different types of networks, e.g., PSTN and VoIP  media gateways
Network services
DNS, TFTP, FTP, DHCP, HTTP, Telnet, RADIUS, and DIAMETER
Session border control functions
signaling and/or bearer traffic as it crosses a trust boundary
November 2006
VoIPSec
VoIPSA report

4. Multi-party freedom model
People can move from role to role:
Initiating contact
Joining communication in progress
Accepting contact
Terminating communication in progress
Refusing contact
November 2006
VoIPSec

5. VoIP threat taxonomy
November 2006
VoIPSec

6. User requirements and goals
User is able to …
… invite anyone
… to join multiple parties
… refuse an invite
… drop out of a session
… indicate consent for any and all contact and reporting
… refuse consent for any and all contact and reporting
… set policies for the user and all legally subordinate domains
user is assured confidentiality and immunity for lawful communication
November 2006
VoIPSec

7. Privacy and security
The Privacy Concept = privilege of all people to have their communication systems and content free from unauthorized access, interruption, delay or modification
consent of the person claiming privacy
within the limits of the law
Security =
the right to protect privacy,
a method of achieving privacy
ways to keep communication systems and content free from unauthorized access, interruption, delay or modification
November 2006
VoIPSec

8. Social threats: Misrepresentation
Misrepresentation includes the delivery of information which is false as to the identity, authority or rights of another party or false as to the content of information communicated
identity
authority (false authentication)
rights (false authorization)
content (audio, video, text)
Examples:
false caller ID, organization, name
voice masking and impersonation
false presence information
“phishing”, “vishing”
social engineering (see ChoicePoint)
false claim of government authority
November 2006
VoIPSec

9. Social threats: Theft of services
Theft of services is any unlawful taking of an economic benefit of a service provider by means intended to deprive the provider of lawful revenue or property.
unauthorized deletion or altering of billing records
unauthorized bypass of lawful billing systems
unauthorized billing
taking of service provider property
Common in PSTN
e.g., resale of services with delayed billing
“blue boxes”
November 2006
VoIPSec

10. Social threats: unwanted contact
Unwanted contact is any contact that either bypasses prior affirmative consent (opt-in) or a refusal of consent (opt-out)
Can be illegal (harassment, extortion, fraud) or just unwanted
Harassment
“Harassment is any form of unwanted communication which embarrasses, intimidates, vexes, annoys or threatens the receiver of the communication with actions which are improper under the law.”
Extortion
“Extortion is any act to induce another to do or refrain from any conduct or give up any freedom, right, benefit or property, under a threat of loss or harm to the person, their reputation, property or the health, safety, reputation or welfare of anyone they know.”
November 2006
VoIPSec

11. Resources Security consideration sections in RFCs
November 2006
VoIPSec