Hi Deb,

On 04.04.2024 13:45, Deb Cooley via Datatracker wrote:

Shepherd writeup:  It would be nice to enumerate the manufacturers that have
implemented this concept.  The link to 'https://mudmaker.org' causes my browser
to throw big flashy warning signs.  When I click through them, it tells me to
'GO AWAY'.  fun...

Hi Deb.  There was a config error on a server.  It's fixed. Thanks for pointing it out.


Section 3.1 upgrade causes vulnerabilities:  One would think that this
situation should be avoided at all costs.  There could be a way for the device
to signal which version of F/W it is running, allowing the MUD file to be
tailored.

This may or may not be possible.  It depends on how the MUD URL is communicated.  If it's communicated in a certificate, then the cert would have to change, and as 802.1AR makes clear, that's not supposed to happen.  I hold out hope that SUIT will provide a better path here, but these are still early days.

I should point out that in the vast majority of cases, a MUD URL rarely has to change because you can have a superset of access that won't be at all harmful (a good example would be adding a new new endpoint that is used by new versions).  The corner case is primarily about services being turned off.


Section 3.2:  The same applies for this section as well.  False positives can
be just as dangerous (because they bury the real positives).

Section 4:  Updating IDevID URLs can't be updated with a F/W update?  F/W
updates are signed by the manufacturer's signing key, correct?

See above.  Not permitted by 802.1AR.  But there may be a more SUITable fix over time.

I'll leave the the rest to Michael.

Eliot


Section 4.2:  Just how hard would it be to specify the CA certificate paired
with a subject name (subject alt name, or CN)?  Seems like this is more secure
than your proposed methods.  Oddly enough, Section 5.1 proposes this.

Section 5, last para:  Instead of subject names, SKI should be used [RFC5280,
section 4.2.1.2].  This can be easily checked in a certificate validate that is
presented.

Section 5.2:  Can't this be used all the time?

Section 5.3.3:  Classically to change a 'root' one signs the new with the old
and signs the old with the new.  If it is done this way, I suspect one could
change whatever names, CAs one needs to change.

Section 7:  One might argue that the use of server authenticated TLS might
mitigate a bunch of concerns.

Section 9.  This is confusing. Please seperate the before issues and the after
issues into seperate sections (at least). There are many potential
vulnerabilities listed earlier in the draft.  Please consolidate those here
(possibly with draft section links to where the mitigation is suggested).


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COMMENT:
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Nits:
Section 1, para 6: change 'check the signatures, rejecting files whose
signatures do not match' to '... whose signatures do not validate'.  Using
language like 'match' leads to bad behavior, when the entity should be taking a
positive action to validate the signature.

Section 9, last sentence:  jargon?  I'm not sure I know what this means, and
English is my (only) language.



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