Home > Articles > Security > Network Security

VoIP Threat Taxonomy

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

Threats Against Integrity

Another category of VoIP threat is the threat against integrity, which impacts current service severely in most cases.

The basic method of the integrity threat is altering messages (signals) or media after intercepting them in the middle of the network. That is, an attacker can see the entire signaling and media stream between endpoints as an intermediary. The alteration can consist of deleting, injecting, or replacing certain information in the VoIP message or media.

This section is divided into two types of threat at a high level:

  • Threats against message integrity (message alteration)
  • Threats against media integrity (media alteration)

The next section describes and gives examples of each type of threat.

Message Alteration

Message alteration is the threat that an attacker intercepts messages in the middle of communication entities and alters certain information to reroute the call, change information, interrupt the service, and so on. The typical examples are call rerouting and black holing.

Call Rerouting

Call rerouting is any unauthorized change of call direction by altering the routing information in the protocol message. The result of call rerouting is either to exclude legitimate entities or to include illegitimate entities in the path of call signal or media.

Figure 2-7 illustrates the example of including a malicious entity during call setup.

Figure 2-7

Figure 2-7 Call Rerouting

In Figure 2-7, an attacker keeps monitoring the call request message (for example, SIP INVITE) from User A to a redirect server. When User A initiates a call, the IP phone sends an INVITE message to the redirect server, as shown in Example 2-3.

Example 2-3. IP Phone Sends an INVITE Message to the Redirect Server

INVITE sip:Bob@192.168.10.10:5060 SIP/2.0
Via: SIP/2.0/UDP 10.10.10.10:5060;branch=z9hG4bK00002000005
From: UserA <sip:UserA@10.10.10.10:5060>;tag=2345
To: Bob <sip:Bob@192.168.10.10>
Call-Id: 9252226543-0001
CSeq: 1 INVITE
Contact: <sip:UserA@10.10.10.10>
Max-Forwards: 70
Content-Length: 0

The attacker detects the INVITE and intercepts the response message (that is, "302 Moved Temporarily") from the redirect server, as shown in the continuation of Example 2-3.

SIP/2.0 302 Moved Temporarily
From: UserA <sip:UserA@10.10.10.10:5060>;tag=2345
To: Bob <sip:Bob@192.168.10.10>;tag=6789
Call-Id: 9252226543-0001
CSeq: 1 INVITE
Contact: <sip:Bob@10.1.1.10>
Content-Length: 0

The attacker replaces the IP address of the proxy server (10.1.1.10) in the Contact header with his proxy server (172.26.1.10), and sends to the IP phone, as shown in the continuation of Example 2-3.

SIP/2.0 302 Moved Temporarily
From: UserA <sip:UserA@10.10.10.10:5060>;tag=2345
To: Bob <sip:Bob@192.168.10.10>;tag=6789
Call-Id: 9252226543-0001
CSeq: 1 INVITE
Contact: <sip:Bob@172.26.1.10>
Content-Length: 0

The IP phone sends a new INVITE to attacker's proxy server rather than the legitimate server, and his server relays the message as shown in the picture. From now on, the attacker in the middle can see all signals between the endpoints and modify for any malicious purpose.

Call Black Holing

Call black holing is any unauthorized method of deleting or refusing to pass any essential elements of protocol messages, in the middle of communication entities. The consequence of call black holing is to delay call setup, refuse subsequent messages, make errors on applications, drop call connections, and so on. Here are a few examples with SIP:

  1. An attacker as an intermediary drops only ACK messages between call entities so that the SIP dialog cannot be completed, even though there could be early media between them.
  2. An attacker as an intermediary deletes media session information (SDP) in the INVITE message, which could result in one-way audio or call disconnection.
  3. An attacker as an intermediary refuses to pass all messages to a specific user (victim) so that the user cannot receive any inbound calls.

The call rerouting and black holing belong to message alteration as previously described. The next section covers media alteration as part of the threat against integrity.

Media Alteration

Media alteration is the threat that an attacker intercepts media in the middle of communication entities and alters media information to inject unauthorized media, degrade the QoS, delete certain information, and so on. The media can be voice-only or integrated with video, text, fax, or image. The typical examples are media injection and degrading.

Media Injection

Media injection is an unauthorized method in which an attacker injects new media into an active media channel or replaces media in an active media channel. The consequence of media injection is that the end user (victim) may hear advertisement, noise, or silence in the middle of conversation. Figure 2-8 illustrates the example with voice stream.

Figure 2-8

Figure 2-8 Media Injection

In Figure 2-8, User A with an IP phone makes a call to User B who has a PSTN phone through a media gateway. After the call setup, the IP phone sends voice (RTP) packets to the media gateway. An attacker in the middle monitors the RTP sequence number of the voice packets, and adjusts the sequence number of illegitimate packets (for example, advertisements), and injects them into the voice channel so that they will arrive before the legitimate packets. User B in PSTN hears the injected voice.

Media Degrading

Media degrading is an unauthorized method in which an attacker manipulates media or media control (for example, Real-Time Control Protocol [RTCP]) packets and reduces the QoS of any communication. Here are a couple of examples:

  1. An attacker intercepts RTCP packets in the middle, and changes (or erases) the statistic values of media traffic (packet loss, delay, and jitter) so that the endpoint devices may not control the media properly.
  2. An attacker intercepts RTCP packets in the middle, and changes the sequence number of the packets so that the endpoint device may play the media with wrong sequence, which degrades the quality.

In this section so far, you have learned about VoIP threats against integrity such as message alteration (call rerouting, call black holing) and media alteration (media injection, media degrading). The next section covers another type of threats: social threats.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020