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Re: Suggested changes to the admission policy of the vulnerability pre-disclosure list


Jan Beulich @ 2021-07-16 09:52 CEST:

> On 15.07.2021 23:23, Charles-H. Schulz wrote:
>> Hello,
>> I /we /Vates would like to suggest some changes to the policy regarding the
>> enrollment to the pre-disclosure mailing list of the Xen Security Team.
>> We have had some talks with the French national CERT who has a need to be the
>> recipient of such a list. This national CERT -and in my experience other
>> national CERTs such as the NIST for instance- is in constant contact with a
>> large Xen userbase that is mostly made up of large parts of the public sector
>> as well as critical infrastructure operators belonging to the private
>> sector. For confidentiality reasons they cannot disclose who uses Xen and
>> where it is used nor who may be using it internally or within the related
>> national cybersecurity authority.
>> Because of that, their request may not be clear or matching the existing
>> criteria for inclusion in the mailing list. National CERTs are trusted
>> actors and have historically been among the very first entities to define,
>> advocate for and put in practice the very notion of responsible
>> disclosure. Much of the current practice of Open Source projects in that
>> regard actually stems from CERTs. As part of their policies and processes
>> regarding vulnerability disclosure, the notion of confidentiality and
>> documented, waterfall-like processes of disclosure is play an integral
>> part of
>> how they handle informaton and publicity around vulnerability. As a result,
>> national CERTs (and the French National CERT) do not spread undisclosed
>> vulnerability without following established and agreed-upon processes. Such
>> processes include, in our instance, the ones defined and followed by the Xen
>> Security Team. Compliance with these are the first criteria to earn trust and
>> respect from the ecosystem and the downstream users. You can see an example
>> of their work here: https://www.cert.ssi.gouv.fr/
>> Part of the mission of the French National CERT is to work with
>> critical infrastructure providers in securing their IT.
>> This kind of expertise entails the securing of these information
>> systems before any unforeseen incident as well as after the incident
>> (incident remediation).
>> None of the tasks involved imply the communication of zero-day types
>> of vulnerabilities or vulnerabilities that are unpublished to the
>> downstream users.
> Would you mind shedding some light on the benefits of a national CERT
> being in the know of unpublished vulnerabilities when they can't share
> that knowledge with their downstreams, and hence their downstreams -
> as long as they aren't themselves members of our predisclosure list -
> would still be zero-dayed at the time of publication of such
> vulnerabilities? Shouldn't their advice to their downstreams rather be
> to direct them towards applying for pre-disclosure list membership?

In practice, most of the downstream users that the CERTs work with are not
going to subscribe to the Xen pre-disclosure list, nor to any pre-disclosure
lists of vendors or Open Source Software projects. The downstream users will
work with CERTs and various cybersecurity service providers (Security
Operations Centers -SOCs- being a typical example) in order for vulnerability
discovery, disclosure, patching and later integration of fixes or remediatory
measures be managed and applied.

So a national CERT being in the loop of such advanced, upstream vulnerability
pre-disclosures list is pretty much what a CERT does when it's not publishing
security advisories of some kind. There are several benefits for a CERT:
- threat intelligence and analysis: one vulnerability discovered in one
  source may not be an isolated "incident" - it may be connected to a broader
  attack made of the exploitation of several vulnerabilities found across
  different software stacks. This also providers valuable information about the
  threat landscape and relevance. For instance, Xen having several
  vulnerability reports is one thing, but what happens if KVM receives a batch
  of previously unknown vulnerabilities roughly at the same time? For a CERT,
  that level of information can be very important (sometimes "national
  security" important)

- because of a CERT being a nexus of several threat information/intelligence
  by being as upstream as it can on critical software components, it can then
  act -not by disclosing or patching yet unpublished vulnerabilities on its
  own- by setting the effective patching and remediation work on the
  information systems it is in charge of protecting. In the case of a
  national CERT, such as the CERT-FR, that would be the French central
  administration networks and information systems. Essentially it would
  prioritize the response given the specific level and nature  of threats and 
  presence of vulnerabilities on the systems (i.e: first patch MS Office,
  then Apache httpd, then the vulnerability XYZ00123 on Xen as it really
  affects only a small part of our Xen deployments).

- last but not least, CERTs act as central vulnerability reports
  "broadcasters". CERT users/subscribers/clients point to CERTs to receive
  their daily security watch and alerts. 

> As to the actual policy - how would you propose to categorize such
> organizations, i.e. how would a new bullet point in the present
> "
> This includes:
>     Public hosting providers;
>     Large-scale organisational users of Xen;
>     Vendors of Xen-based systems;
>     Distributors of operating systems with Xen support.
> "
> look like in your opinion? This is pretty important imo, as it will
> need to be understood who else might then become eligible.

I think it's either a very difficult or a very simple question. If I were to
suggest to simply add a line with "national CERTs" meaning: CERTs that
operate on behalf of governments for the protection and cybersecurity watch
of national administration and critical infrastructures" would that be
accepted? I'm happy with that one. It's really two criteria I'm adding: being
a CERTs acting wth a clear mandate from a national authority to serve as the
national computing emergency response team. Not sure how satisfactory that

All the best,
Charles-H. Schulz
Chief Strategy Officer - CSO
XCP-ng & Xen Orchestra - Vates solutions



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