Network Endpoint Assessment
Network Endpoint Assessment WG
||Network Endpoint Assessment
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Network Endpoint Assessment (NEA) architectures have been implemented
in the industry to assess the "posture" of endpoint devices for the
purposes of monitoring compliance to an organization's posture policy
and optionally restricting access until the endpoint has been updated
to satisfy the posture requirements. An endpoint that does not comply
with posture policy may be vulnerable to a number of known threats that
may exist on the network. The intent of NEA is to facilitate corrective
actions to address these known vulnerabilities before a host is exposed
to potential attack. Note that an endpoint that is deemed compliant may
still be vulnerable to threats that may exist on the network. The
network may thus continue to be exposed to such threats as well as the
range of other threats not addressed by maintaining endpoint
Posture refers to the hardware or software configuration of an endpoint
as it pertains to an organization's security policy. Posture may
include knowledge that software installed to protect the machine (e.g.
patch management software, anti-virus software, host firewall software,
host intrusion protection software or any custom software) is enabled
and up-to-date. An endpoint supporting NEA protocols can be queried for
An organization may make a range of policy decisions based on the
posture of an endpoint. NEA is not intended to be prescriptive in this
regard. Supported deployment scenarios will include, but are not
limited to, providing normal access regardless of compliance result
along with any recommendations for remediation ("advisory mode"), as
well as providing restricted access sufficient for remediation purposes
and any essential services until an endpoint is in compliance
("mandatory mode"). Specifying mechanisms for providing restricted
access is outside the scope of the NEA WG.
Since NEA involves many different components from different vendors,
interoperability is important. The NEA working group will
develop standard protocols at the following three layers in the
the Posture Attribute protocol (PA), the Posture Broker protocol
(PB), and the Posture Transport protocol (PT). PA and PB will be
support a variety of PT protocols. Together, PA, PB and the mandatory to
implement PT protocols will allow interoperability between an NEA Client
from one vendor and an NEA Server from another.
Since there are already several non-standard protocols at these
layers, the NEA working group will consider these existing protocols as
candidates for the standard protocols. A requirements document will be
written and used as a basis for evaluating the candidate protocols. The
working group may decide to standardize one of the candidate protocols,
use one of them as a basis for a new or revised protocol, or decide
that a new protocol is needed.
The NEA Requirements document will include a problem statement,
definition of terms, requirements for the PA and PB protocols, and an
overall security analysis. It will also include generic requirements
for the protocol transporting PA, PB: the Posture Transport protocol
The PA (Posture Attribute) protocol consists of posture attributes that
are carried between a particular Posture Collector in a NEA client and
a particular Posture Validator in a NEA Server. The PA protocol is
carried inside the PB protocol. A base set of standard posture
attributes will be specified that are expected to address many common
posture policies. Vendor-specific attributes will also be supported;
vendor-specific attributes will be identified by a private enterprise
number and a vendor assigned value. Vendors are strongly encouraged to
document vendor-specific attributes in an RFC. The NEA WG will
investigate the use of a standard syntax for all attributes.
The PB (Posture Broker) protocol aggregates posture attributes from one
or more Posture Collectors in an NEA client and sends them to the NEA
server for assessment by one or more Posture Validators.
The PT (Posture Transport) protocol carries the PB protocol. The
is that the PT protocol is a shim protocol that defines an
encapsulation of PB
within an existing standard transport protocol. Existing standard transport
protocols will be leveraged to the extent possible. The NEA WG may specify
more than one PT to meet the requirements of different deployment
The NEA WG will specify at least one mandatory to implement PT protocol.
PT protocol specifications must describe any limitations
that they impose on PB and PA (e.g. half duplex).
One commonly discussed issue with NEA systems is how to handle
compromised endpoints, whose reports of their own posture may not be
accurate. Detecting or handling such endpoints is out of scope of the
NEA WG. Work on PA will focus on attributes useful for assessing
posture of those endpoints reporting accurate information. However, the
protocols developed by the NEA WG must be designed to accommodate
emerging technologies for identifying and dealing with lying endpoints.
Note that NEA is not chartered to develop standard protocols for
remediation. NEA is intended to be used with new or existing tools that
can be used in the absence of NEA. NEA is applicable to computing
enterprise environments, where endpoints accessing the enterprise's
network are owned and/or expected to conform to the policies set forth
by the organization that owns and operates the network. All other
cases are outside the scope of the NEA charter, since we do not know
that NEA would be useful in such cases. NEA applicability and security
considerations will be described in the appropriate NEA documents.
Further work in the NEA WG will be considered via the rechartering
process after the completion of these milestones.