Hi Raj,
>Do you have any proposals or text w.r.t the threat model writeup? Also
>from an IETF perspective regarding threat models, please see Peter's
>email: http://www.ietf.org/mail-archive/web/paws/current/msg00592.html
>
>-Raj
I'll spend a little time formalizing the ideas I submitted below. However,
"threats" are part of a complete set of requirements and looking at the current
proposal, I feel we need to clarify the service that we offer before we can say
what are real threats. Specifically, the threat:
>>> device which can be used maliciously. The effect of such an
>>> attack being successful would result in a malicious client
>>> replaying the stolen authentication/authorization secrets to a
>>> white space database.
This is not a threat as worded... but why?
We need to define what we offer, and then things that prevent or break these
offered services are potential risks that can be mapped to threats. As a
start, I propose (which I hope is mostly in line with the use cases) two main
services with some subtopics:
1) Prevent Interference of License-exempt Use with Licensed Operation
- Support changes in channel, time Period and region for licensed
operation
- Support predictable availability of licensed channels
- Support the ability to disable specific vendor/model-types from
operation when
they are determined to be causing interference
2) Enable Authorized Channel Utilization for License-exempt Operation
- Facilitate fixed use of channels
- Facilitate mobile use of channels
- Facilitate indoor use of channels
- Support predictable availability of license-exempt channels
- Support changing of authorized channels to prevent interference with
licensed usage
So, threat event is something that has a result of preventing the promised
services. The threat event either causes unapproved interference with licensed
operation, or it prevents White Space "license-exempt" operation.
The "Support Predictable Availability" is something new I'd like to introduce
for discussion. There needs to be a expectation that once you are using a
channel that your use will not be terminated abruptly in an unanticipated
manner. Right now - we are creating mechanism to quickly cutoff a device for
any reason at all (for the use case of mobile microphones). This is actually
supposed to be a predictable event with some type of scheduling. An
license-exempt devices needs to be able to determine how long it might operate
under the regulations in a particular channel/region. Building a system where
you never know when your communications might get cut off seems like a bad
idea.
Paul
>
>On 1/27/12 5:24 PM, "ext Paul Lambert" <[email protected]> wrote:
>
>>It's good to have requirements based on such an analysis. This is an
>>interesting start, but we may be mixing threats, vulnerabilities and
>>mechanisms.
>>
>>Threats are typically tied to an actor ... human or not. I'm not sure
>>it's worth going hard over to something like the NIST 800-30
>definitions
>>of threats, but within this framework the threats are Governments,
>>disgruntled insiders, tsunamis etc. Being the IETF we can jump more
>>quickly to the threat event and specifics of an attack, but should at
>>least expand threats to include natural events and connectivity
>problems.
>> Robustness or emergency modes might be interesting to consider.
>>
>>We also have a problem in this analysis of perspective - are we
>>considering threats as viewed from regulatory agency or the end device
>>owner or both. We should consider both - but they are contradictory
>>perspectives. Users want continuity of service. Governments (the
>>regulators) want control of the airwaves.
>>
>>Most of the real threats that we have are nearly impossible to prevent
>at
>>the protocol level. It's still worth examining the threats to see
>where
>>we stand.
>>
>>On the current document threats:
>>
>>>o It is assumed that the master device or the white space database
>>> have NOT been compromised from a security standpoint.
>>>
>>>Threat 1: Obtain master device authentication/authorization secrets
>>> The master device needs to authenticate itself with the white
>>> space database prior to requesting channel information. The
>>> attacker may try to get access to the secrets of the master
>>> device which can be used maliciously. The effect of such an
>>> attack being successful would result in a malicious client
>>> replaying the stolen authentication/authorization secrets to a
>>> white space database.
>>This does not seem consistent with the prior statement of "not
>>compromised".
>>Restatement
>>
>>Threat: User modifies a device to masquerade as another valid certified
>>device.
>>
>>This is an interesting case where threat/vulnerability/risk play
>>together. The FCC or other regulatory agencies want traceability of
>>devices. If a user wants to run a rogue radio, there is no reason to
>>access the database (low risk - no payoff). The only reason this would
>>be an interesting attack might be to avoid tracking and have some
>>anonymity.
>>
>>>Threat 2: Spoofed white space database
>>> A master device discovers a white space database(s) thru which
>>> it can query for channel information. The master device needs
>>> to ensure that the white space database with which it
>>> communicates with is an authentic entity. The white space
>>> database needs to provide its identity to the master device
>>> which can confirm the validity/authenticty of the database. An
>>> attacker may attempt to spoof a white space database and
>>> provide responses to a master device which are malicious and
>>> result in the master device causing interference to the primary
>>> user of the spectrum.
>>
>>I think this is two types of threat events:
>> - malicious denial of service or intentional interference with
>incumbents
>> - impersonation of white space database to enable operation of a
>device
>>that may
>> not otherwise be possible (blocked device, unallocated channels).
>>This may or may not
>> interfere with incumbent devices
>>
>>>Threat 3: Modifying a query request
>>...
>>
>>>Threat 4: Modifying a query response
>>Seems like these two could be lumped together ...MiTM modifies protocol
>>messages to:
>> - deny service
>> - interfere with incumbents
>> - provide unauthorized channel usage (most likely risk IMHO)
>>
>>>Threat 5: Using query response information
>>> An attacker may be a master device which is not certified for
>>> use by the relevant regulatory body. The attacker may listen to
>>> the communication between a valid master device and white space
>>> database and utilize the information about available channels
>>> in the response message by utilizing those channels. The result
>>> of such an attack is unauthorized use of channels by a master
>>> device which is not certified to operate.
>>As stated this is a mechanism - a clearer statement might be.
>>
>>Threat: Unauthorized use of channels by an uncertified device.
>>
>>Anyone can already go to a database and find available channels. If a
>>device can operate without going to the database there is nothing that
>>paws can do to stop it operating in available or non-available
>channels.
>>
>>Just to get some discussion going -here's a couple more possible
>threats..
>>
>>Threat: Third party tracking of white space device location
>> Likely a valuable commodity to sell for advertizing with no
>technical
>>design or policy for privacy
>>Threat: Database owner termination of device service for reasons other
>>than incumbent protection
>>
>>
>>
>>Paul
>>
>>
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