RE: VoIP Assessment

From: Mark Teicher (mht3_at_earthlink.net)
Date: 07/22/05

  • Next message: Scott Fuhriman: "Unknown App"
    Date: Thu, 21 Jul 2005 20:12:31 -0400
    To: "Bob Bell (rtbell)" <rtbell@cisco.com>
    
    

    Bob -

    *If this mail thread is picked up by CBS Radio, Discovery Channel or
    CNN, you can take all the credit* :)

    As the various entities have reported, that combining voice with data
    is tricky, some early questions to ask before discussing encrypting
    sessions between end points, gateways and media servers is 1) The
    capability of the existing network to provide VoIP Calls and the
    quality of the calls under different network situations. Most
    organizations may outsource this to a number of various VoIP hardware
    or software providers by measuring simulated VoIP traffic and
    calculating MOS and QOS. The blanket statement that "VoIP is not
    secure" can be supported by general security recommendations that
    have been published by various sources :
    1) Encrypt VoIP Traffic over a VPN
    2) Firewalls should be properly configured and validate that firewall
    vendors have support for SIP and H.323
    3) Segmentation of voice and data traffic by utilizing VLAN network
    configurations
    4) Implement proxy servers in front of firewalls to process incoming
    and outgoing voice data and
    5) Validate that server-based IP PBXs are secure
    6) Ensure that your virus software is up to date
    7) Implement IDS/IPS solutions to protect against Denial of Service Attacks.

    According to the whitepaper published by
    http://csrc.nist.gov/publications/nistpubs/800-58/SP800-58-final.pdf:
    " Because of the integration fo voice and data in a single network,
    establishing a secure VoIP and data network is a complex process that
    requires greater effort that that required for data-only networks."

    Validating whether a particular VoIP solution is secure is very
    complex, and is not solved by conducting a network security
    assessment to validate whether the underlying operating system of a
    media gateway has implemented iptables/ipfilt correctly or if IP
    phones are susceptible to trivial DOS attacks. Developing ways
    of some of the security features inherently lacking in VoIP
    solutions is just beginning for some vendors, others are scrambling
    to present their business plans to venture capitalists who would like
    to capitalize on the fear of organizations, and some groups
    attempting to jump start a security consulting practice focusing on
    VoIP security.

    At 11:17 AM 7/21/2005, Bob Bell (rtbell) wrote:
    >Mark -
    >
    >My point is that IP Telephony within an enterprise can be secure. There
    >are many things which can be done (such as strong authentication of the
    >endpoints [both the call control agent and the communications
    >endpoint)in conjunction with encrypted and authenticated signaling and
    >media flows, control of provisioning information and images in such a
    >manner that the probability of corruption or modification is extremely
    >low, etc. The blanket statement that "VoIP is not secure" is extremely
    >misleading. If you apply no safeguards to the system (note I am
    >indicating a system level protection) then I would agree with you that,
    >just like file transfers or database access or any of the other
    >applications that exist on a network, it is not secure. If on the other
    >hand, reasonable measures are taken (and there are commercial products
    >that do take them) then the level of security is commenserate with the
    >level of risk.
    >
    >There are a large number of organizations today who are getting a great
    >deal of press coverage by claiming that "the sky is falling" when they
    >are making assumptions that are simply not true. One of the ones that
    >really gets to me is that if you do IP Telephony, you must admit into
    >your network directly any attempted VoIP calls that come at you by
    >opening holes in the perimeter fire walls to admit the traffic. First of
    >all, that is not realistic. We do not do that for web access, nor email
    >access nor any other form of access, why in the world would we do it for
    >voice. It will go through a gateway type device on a DMZ so that the
    >messaging can truly be validated and verified and so that the external
    >party does not have access to information that the corporation deems
    >confidential. Secondly, if it is a remote worker, then the connection
    >will involve a VPN link and so will not be admitted unchecked either.
    >Just because the standards groups envisioned a totally uncontrolled
    >environment, there is nothing that required enterprises (or residential
    >users for that matter) to simply close their eyes and say "cut here".
    >
    >I would agree that there are some "security" consultants that may not be
    >either as complete and accurate as they should be in this area. But that
    >is true of all consultants and all areas. We should not blindly reject
    >as "unprotectable" or "unsecurable" a system that has been demonstrated
    >to be securable.
    >
    >We, the security forces, need to assess the risks and remediation
    >methods to determine both effectiveness and functionality. We must make
    >IPT or VoIP into a viable technology with the protections that are
    >required. We cannot simply assert that there is no hope, because there
    >is.
    >
    >Bob
    >
    > > -----Original Message-----
    > > From: Mark Teicher [mailto:mht3@earthlink.net]
    > > Sent: Wednesday, July 20, 2005 20:24
    > > To: Bob Bell (rtbell)
    > > Cc: intel96; pen-test@securityfocus.com
    > > Subject: RE: VoIP Assessment
    > >
    > > Fundamentally, VoIP is not secure, as originally stated, It
    > > depends on what an organization is attempting to validate.
    > > Network security consulting practices will attempt to dazzle
    > > an organization with their "VoIP assessment or VoIP Readiness
    > > services" . Some concentrate more on VoIP network readiness
    > > and propose bandwidth analysis utilizing tools that either
    > > home grown or commercial. This may provide some insight on
    > > jitter, latency and other such issues when implementing or
    > > migrating to a VoIP infrastructure. Discussion of security
    > > issues arise when "former security investigators" or "Ph D"
    > > types get involved in the discussion and start rattling off
    > > statements "As telephone communications move to the IP world,
    > > it will become increasingly easier to intercept and monitor
    > > telephone calls by anyone." and "How businesses handle
    > > threats to their
    > > converged network will be crucial to their success." Great buzzword
    > > statements, but they miss the questions that an organization
    > > may have r egarding the underlying security of VoIP and the
    > > various aspects of enabling options that allow for
    > > availability and ease of use for end users.
    > >
    > >
    > >
    > >
    > > At 11:24 AM 7/20/2005, Bob Bell \(rtbell\) wrote:
    > > >Mark, Intel96 -
    > > >
    > > >There are a lot of conflicting opinions floating around as to the
    > > >security of VoIP systems. One of the things that you need to do is
    > > >establish whether you are dealing with a bounded system, (i.e. an
    > > >enterprise PBX replacement) or an unbounded one (i.e. SKYPE) as they
    > > >have considerable differences in both their vulnerability and the
    > > >resources available to deal with issues. Secondly, security
    > > of VoIP is
    > > >not a single dimensional problem. Many of the issues of
    > > protecting VoIP
    > > >occur a layers far below the application layer which is where VoIP
    > > >lives. So, you need to examine the issue from a systems approach not
    > > >simply a point solution for VoIP. Finally, there is a great
    > > deal more
    > > >to providing SYSTEMIC protection beyond simply protecting
    > > the protocol.
    > > >This includes things like the provisioning of the endpoints, the
    > > >control of and validation of the images contained in the
    > > endpoints, the
    > > >authentication and authorization schemes for the endpoints
    > > and users,
    > > >etc. If I can be of help, please feel free to contact me.
    > > >
    > > >Bob
    > > >
    > > >IPCBU Security Architect
    > > >Cisco Systems, Inc.
    > > >576 S. Brentwood Ln.
    > > >Bountiful, UT 84010
    > > >801-294-3034 (v)
    > > >801-294-3023 (f)
    > > >801-971-4200 (c)
    > > >rtbell@cisco.com
    > > >
    > > >
    > > > > -----Original Message-----
    > > > > From: Mark Teicher [mailto:mht3@earthlink.net]
    > > > > Sent: Tuesday, July 19, 2005 16:40
    > > > > To: intel96
    > > > > Cc: pen-test@securityfocus.com
    > > > > Subject: Re: VoIP Assessment
    > > > >
    > > > > What specific items have you been tasked to validate?
    > > > > Could be as simple as :
    > > > > Are the components VoIP capable?
    > > > > If so, then what protocols have been implemented
    > > > > (Y/N)
    > > > > If x protocol, if implemented correctly (i.e
    > > > > when enabled, does it process the traffic correctly (Y/N)
    > > > > If x protocol, if implemented correctly
    > > > > (i.e. when x protocol is disabled, does it block VoIP traffic
    > > > > inbound/outbound? (Y/N)
    > > > >
    > > > > and so and so on
    > > > >
    > > > > Lots of those "security" type experts will overstate the
    > > obvious and
    > > > > start rattling off big words like MITM attacks, Resource
    > > exhaustion,
    > > > > H.323 attacks, SIP Overflow attacks, etc, etc, but IMHO, simplify
    > > > > what the tasks are, and break those tasks into simple
    > > steps that any
    > > > > former senior security consultant can do by utilizing a checklist
    > > > > approach, otherwise one gets into the battle with the "puffed out
    > > > > chest security wannabes "
    > > > >
    > > > > /m
    > > > > At 01:40 PM 7/19/2005, intel96 wrote:
    > > > > >I have been asked to look at the security of a VoIP
    > > > > architecture. Has
    > > > > >anyone conducted a security assessment against VoIP or the
    > > > > components
    > > > > >that make up the architecture?
    > > > > >
    > > > > >Thanks,
    > > > > >
    > > > > >Intel96
    > > > >
    > >


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