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Created Apr 23, 2013
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<h1> Security Problem Response Process</h1>
<p>Computer systems have bugs. Currently recognised best practice for bugs
with security implications is to notify significant downstream users in
private; leave a reasonable interval for downstreams to respond and prepare
updated software packages; then make public disclosure.</p>
<p>We want to encourage people to report bugs they find to us. Therefore we
will treat with respect the requests of discoverers, or other vendors, who
report problems to us.</p>
<h2>Scope of this process</h2>
<p>This process primarily covers the <a href="">Xen Hypervisor Project</a>. Vulnerabilties reported against other projects will be handled on a best effort basis by the relevant Project Lead together with the security team.</p>
<h2>Specific process</h2>
<ol type="1">
<li><p>We request that anyone who discovers a vulnerability in
software reports this by email to security (at) xen (dot) org.</p>
<p>(This also covers the situation where an existing published
changeset is retrospectively found to be a security fix)</p></li>
<li><p>Immediately, and in parallel:</p></li>
<ol type="a">
<li><p>Those of us on the team who are aware of the problem
will notify security@xen if disclosure wasn't made there
<li><p>If the vulnerability is not already public, security@xen will
negotiate with discoverer regarding embargo date and disclosure
schedule. See below for detailed discussion.</p></li>
<li>Furthermore, also in parallel:</li>
<ol type="a" start="3">
<li><p>security@xen will check whether the discoverer, or other people
already aware of the problem, have allocated a CVE number. If
not, we will acquire a CVE candidate number ourselves, and
make sure that everyone who is aware of the problem is also
aware of the CVE number.</p></li>
<li><p>If we think other software systems (for example, competing
hypervisor systems) are likely to be affected by the same
vulnerability, we will try to make those other projects aware
of the problem and include them in the advisory preparation
<p>(This may rely on the other project(s) having
documented and responsive security contact points)</p>
<li><p>We will prepare or check patch(es) which fix the
vulnerability. This would ideally include all relevant
backports. Patches will be tightly targeted on fixing the
specific security vulnerability in the smallest, simplest and
most reliable way. Where necessary domain specific experts
within the community will be brought in to help with patch
<li><p>We will determine which systems/configurations/versions are
vulnerable, and what the impact of the vulnerability is.
Depending on the nature of the vulnerability this may involve
sharing information about the vulnerability (in confidence, if
the issue is embargoed) with hardware vendors and/or other
software projects.</p></li>
<li><p>We will write a Xen advisory including information from (b)-(f)</p></li>
<li><p><b>Advisory pre-release:</b></p>
<p>This occurs only if the advisory is embargoed (ie, the problem is
not already public):</p>
<p>As soon as our advisory is available, we will send it,
including patches, to members of the Xen security pre-disclosure
list. For more information about this list, see below.</p>
<p>At this stage the advisory will be clearly marked with the embargo
<li><p><b>Advisory public release:</b></p>
<p>At the embargo date we will publish the advisory, and push
bugfix changesets to public revision control trees.</p>
<p>Public advisories will be posted to xen-devel,
xen-users and xen-annnounce and will be added to the
<a href="">Security Announcements wiki page</a>.</p>
<p>Copies will also be sent to the pre-disclosure list.</p>
<p>If new information or better patches become available, or we
discover mistakes, we may issue an amended (revision 2 or later)
public advisory. This will also be sent to the pre-disclosure
<li><p><b>Post embargo transparency:</b></p>
<p>During an embargo period the security response team may
be required to make potentially controverial decisions in private,
since they cannot confer with the community without breaking the
embargo. The security team will attempt to make such decisions
following the guidance of this document and where necessary their
own best judgement. Following the embargo period any such
decisions will be disclosed to the community in the interests of
transparency and to help provide guidance should a similar
decision be required in the future.</p>
<h2>Embargo and disclosure schedule</h2>
<p>If a vulnerability is not already public, we would like to notify
significant distributors and operators of Xen so that they can prepare
patched software in advance. This will help minimise the degree to which
there are Xen users who are vulnerable but can't get patches.</p>
<p>As discussed, we will negotiate with discoverers about disclosure
schedule. Our usual starting point for that negotiation, unless there are
reasons to diverge from this, would be:</p>
<ol type="1">
<li><p>One working week between notification arriving at security@xen
and the issue of our own advisory to our predisclosure list. We
will use this time to gather information and prepare our
advisory, including required patches.</p></li>
<li><p>Two working weeks between issue of our advisory to our
predisclosure list and publication.</p></li>
<p>When a discoverer reports a problem to us and requests longer delays than
we would consider ideal, we will honour such a request if reasonable. If a
discoverer wants an accelerated disclosure compared to what we would prefer,
we naturally do not have the power to insist that a discoverer waits for us
to be ready and will honour the date specified by the discoverer.</p>
<p>Naturally, if a vulnerability is being exploited in the wild we will make
immediately public release of the advisory and patch(es) and expect others
to do likewise.</p>
<h2>Pre-disclosure list</h2>
<p> operates a pre-disclosure list. This list contains the email
addresses (ideally, role addresses) of the security response teams for
significant Xen operators and distributors.</p>
<p>This includes:<ul>
<li>Public hosting providers;</li>
<li>Large-scale organisational users of Xen;</li>
<li>Vendors of Xen-based systems;</li>
<li>Distributors of operating systems with Xen support.</li>
<p>This includes both corporations and community institutions.</p>
<p>Here "provider", "vendor", and "distributor" is meant to
include anyone who is making a genuine service, available to the
public, whether for a fee or gratis. For projects providing a
service for a fee, the rule of thumb of "genuine" is that you
are offering services which people are purchasing. For gratis
projects, the rule of thumb for "genuine" is measured in terms
of the amount of time committed to providing the service. For
instance, a software project which has 2-3 active developers,
each of whom spend 3-4 hours per week doing development, is very
likely to be accepted; whereas a project with a single developer
who spends a few hours a month will most likey be rejected.</p>
<p>For organizational users, a rule of thumb is that "large-scale"
means an installed base of 300,000 or more Xen guests. Other
well-established organisations with a mature security response
process will be considered on a case-by-case basis.</p>
<p>The list of entities on the pre-disclosure list is public. (Just the list
of projects and organisations, not the actual email addresses.)</p>
<p>If there is an embargo, the pre-disclosure list will receive
copies of the advisory and patches, with a clearly marked embargo
date, as soon as they are available. The pre-disclosure list will
also receive copies of public advisories when they are first
issued or updated.</p>
<p>Organizations on the pre-disclosure list are expected to
maintain the confidentiality of the vulnerability up to the
embargo date which security@xen have agreed with the discoverer,
and are committing to ensuring that any members/employees of that
organisation who come into contact with confidential information
will do so as well.</p>
<p>Specifically, prior to the embargo date, pre-disclosure list members
should not make available, even to their own customers and partners:<ul>
<li>the advisory</li>
<li>their own advisory</li>
<li>the impact, scope, set of vulnerable systems or the nature
of the vulnerability</li>
<li>revision control commits which are a fix for the problem</li>
<li>patched software (even in binary form) without prior consultation with security@xen and/or the discoverer.</li>
<p>List members are allowed to make available to their users only the following:<ul>
<li>The existance of an issue</li>
<li>The assigned XSA and CVE numbers</li>
<li>The planned disclosure date</li>
<p>Organisations who meet the criteria should contact security@xen
if they wish to receive pre-disclosure of advisories. Please
include in the e-mail: <ul>
<li>The name of your organization</li>
<li>A brief description of why you fit the criteria, along
with evidence to support the claim</li>
<li>A security alias e-mail address (no personal addresses --
see below)</li>
<li>A link to a web page with your security policy
<li>A statement to the effect that you have read this policy
and agree to abide by the terms for inclusion in the list,
specifically the requirements to regarding confidentiality
during an embargo period</li>
<p>Evidence that will be considered may include the following: <ul>
<li>If you are a public hosting provider, a link to a web page
with your public rates</li>
<li>If you are a software provider, a link to a web page where
your software can be downloaded or purchased</li>
<li>If you are an open-source project, a link to a mailing
list archive and/or a version control repository
demonstrating active development</li>
<li>A public key signed with a key which is in the PGP "strong
<p>Organizations already on the list who do not have a security
alias or have not sent a statement that they have read this policy
and will abide by it will be asked to do so.</p>
<p>Organisations should not request subscription via the mailing
list web interface, any such subscription requests will be
rejected and ignored.</p>
<p>A role address (such as should be used
for each organisation, rather than one or more individual's
direct email address. This helps to ensure that changes of
personnel do not end up effectively dropping an organisation
from the list.</p>
<h3>Organizations on the pre-disclosure list:</h3>
<p>This is a list of organisations on the pre-disclosure list
(not email addresses or internal business groups).
<li> security response team</li>
<li>Xen 3.4 stable tree maintainer</li>
<h2>Change History</h2>
<li><b>v1.4 Apr 2013:</b> Predisclosure list criteria changes</li>
<li><b>v1.3 Aug 2012:</b> Various minor updates</li>
<li><b>v1.2 Apr 2012:</b> Added pre-disclosure list</li>
<li><b>v1.1 Feb 2012:</b> Added link to Security Announcements wiki page</li>
<li><b>v1.0 Dec 2011:</b> Intial document published after review</li>
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