Security Event Token (SET)Oracle Corporationphil.hunt@yahoo.comMicrosoftmbj@microsoft.comhttp://self-issued.info/Googlewdenniss@google.comCiscomorteza.ansari@cisco.com
Security
Security Events Working GroupIdentitySecurityEventTokenClaimsJSONJSON Web TokenJWTInternet-Draft
This specification defines the Security Event Token (SET) data structure.
A SET describes a statement of fact from the perspective of an issuer,
which is intended to be shared with one or more recipients.
A SET is a JSON Web Token (JWT),
which can be optionally signed and/or encrypted.
SETs can be distributed via protocols such as HTTP.
This specification defines an extensible Security Event Token
(SET) data structure, which can be exchanged using protocols such as HTTP.
The specification builds on the JSON Web Token (JWT) format
in order to provide a self-contained token that can be optionally
signed using JSON Web Signature (JWS)
and/or encrypted using JSON Web Encryption (JWE) .This specification profiles the use of JWT for the purpose of
issuing Security Event Tokens (SETs). This specification defines a
base format used by profiling specifications to define actual
events and their meanings.
This specification uses non-normative example events to
demonstrate how events can be constructed.This specification is scoped to security and identity related events.
While security event tokens may be used for other purposes, the specification
only considers security and privacy concerns relevant to identity
and personal information.Security Events are not commands issued between parties.
A security event is a statement of fact from the perspective of an
issuer about the state of a security subject (e.g., a web
resource, token, IP address, the issuer itself) that the issuer controls or is aware
of, that has changed in some way (explicitly or implicitly). A
security subject MAY be permanent (e.g., a user account) or
temporary (e.g., an HTTP session) in nature. A state change could
describe a direct change of entity state, an implicit change of state,
or other higher-level security statements such as:
The creation, modification, removal of a resource.The resetting or suspension of an account.The revocation of a security token prior to its expiry.The logout of a user session. Or,
An indication that a user has been given control of an email identifier
that was previously controlled by another user.
While subject state changes are often triggered by
a user agent or security subsystem, the issuance and transmission
of an event may occur asynchronously and in a back channel to
the action that caused the change that generated the security
event. Subsequently, an Event Recipient, having received a SET,
validates and interprets the received SET and takes its own
independent actions, if any. For example, having been informed of
a personal identifier being associated with a different security
subject (e.g., an email address is being used by someone else),
the Event Recipient may choose to ensure that the new user is not granted
access to resources associated with the previous user. Or, the
Event Recipient may not have any relationship with the subject,
and no action is taken.While Event Recipients will often take actions upon receiving
SETs, security events cannot be assumed to be commands or requests.
The intent of this specification is to define a syntax for
statements of fact that Event Recipients may interpret for their own
purposes. As such, SETs have no capability for error signaling
to ensure the validation of a received SET.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .
These keywords are capitalized when used to
unambiguously specify requirements of the protocol or application
features and behavior that affect the inter-operability and security of
implementations. When these words are not capitalized, they are meant
in their natural-language sense.For purposes of readability, examples are not URL encoded.
Implementers MUST percent encode URLs as described in
Section 2.1 of .Throughout this document, all figures MAY contain spaces and extra
line-wrapping for readability and space limitations. Similarly, some
URIs contained within examples have been shortened for space and
readability reasons.
The following definitions are used with SETs:
A SET is a JWT conforming to this specification
that is distributed to one or more Event Recipients.
A service provider that creates SETs to be sent to other providers known
as Event Recipients.
An Event Recipient is an entity that receives SETs through
some distribution method. An Event Recipient is the same
entity referred as a "recipient" or "receiver" in and
related specifications.
A SET describes an event or state change that has occurred
about a Subject. A Subject might, for instance, be a principal (e.g.,
Section 4.1.2 of ), a web resource,
an entity such as an IP address, or the issuer of the SET.
A specification that profiles the SET data structure to define
one or more specific event types and their associated claims and processing rules.
A SET is a JWT data structure that represents
one or more related aspects of a security event about a Subject.
The JWT Claims Set in a SET has the following structure:
The top-level claims in the JWT Claims Set are called the SET "envelope".
Some of these claims are present in every SET;
others will be specific to particular SET profiles or profile families.
Claims in the envelope SHOULD be registered in the
"JSON Web Token Claims" registry or be
Public Claims or Private Claims, as defined in .
Envelope claims that are profiled and defined in this specification
are used to validate the SET and provide information about
the event data included in the SET.
The claim events contains the event identifiers
and event-specific data expressed about the Security Subject.
The envelope MAY include event-specific or profile-specific data.
Each member of the events
JSON object is a name/value pair. The JSON member name is a
URI string value is an event identifier, and the
corresponding value is a JSON object known as the event "payload".
The payload JSON object contains claims that pertain to
that event identifier and need not be registered as JWT claims.
These claims are defined by the Profiling Specification that defines the event.
An event with no payload claims SHALL be represented as the empty JSON object
({}).
When multiple event identifiers are contained in a SET,
they represent multiple aspects of the same state transition
that occurred to the Security Subject.
They are not intended to be used to aggregate distinct events about the same subject.
Beyond this, the interpretation of SETs containing multiple event identifiers
is out of scope for this specification;
Profiling Specifications MAY define their own rules regarding their use of
SETs containing multiple event identifiers, as described in .
Possible uses of multiple values include, but are not limited to:
Values to provide classification information (e.g., threat type or level).
Additions to existing event representations.
Values used to link potential series of events.
Specific-purpose event URIs used between particular Event Issuers and Event Recipients.
The JWT Claims Set consists of:
The events claim specifying the hypothetical
SCIM URN (urn:ietf:params:scim:event:passwordReset)
for a password reset, and a second value,
https://example.com/scim/event/passwordResetExt,
that is used to provide additional event information such as the
current count of resets.The iss
claim, denoting the Event Issuer.The sub claim, specifying the SCIM
resource URI that was affected.The aud claim, specifying the
intended audiences for the event.
(The syntax of the aud claim
is defined in Section 4.1.3 of .)
In this example, the SCIM event
indicates that a password has been updated and the current
password reset count is 5. Notice that the value for
resetAttempts is in the event payload
of an event used to convey this information.
Note that the above SET has an empty JSON object and
uses the JWT registered claims sub
and sid to identify the subject
that was logged out.
In the above example, the attribute iss contained within the
payload for the event https://openid.net/heart/specs/consent.html refers
to the issuer of the Security Subject (sub) rather than the event
issuer https://my.examplemed.com. They are
distinct from the top level value of iss,
which always refers to the issuer of the event - a medical consent
service that is a relying party to the OpenID Provider.
Notice that parameters to the event are included in the event payload, in this case,
the reason and cause-time values.
The account that is the subject of the event is identified using the
iss and sub values,
in the same manner as OpenID Connect ID Tokens.
The following claims from are profiled for use in SETs:
As defined by
Section 4.1.7 of contains a unique
identifier for an event. The identifier SHOULD be unique within
a particular event feed and MAY be used by clients to track
whether a particular event has already been received. This
claim is REQUIRED.
A string identifying the service provider publishing
the SET (the issuer).
In some cases, the SET issuer is not the issuer of the Security Subject.
Therefore, implementers cannot assume that the issuers are the same
unless the Profiling Specification specifies that they are
for SETs conforming to that profile.
This claim is REQUIRED.
The syntax of the
claim is as defined in Section 4.1.3 of .
This claim contains one or more audience identifiers
for the SET. This claim is RECOMMENDED.
As defined by Section 4.1.6 of ,
a value representing when the
event was issued. Unless otherwise specified,
the value SHOULD be interpreted as equivalent
to the actual time of the event. This claim is REQUIRED.
As defined by Section 4.1.2 of ,
a String or URI value representing the principal or the subject of the SET.
This is usually the entity whose "state" was changed. For example,
an IP Address was added to a black list. A URI representing a
user resource that was modified. A token identifier for a revoked
token. If used, the Profiling Specification SHOULD
define the content and format semantics for the value. This claim
is OPTIONAL, as the principal for any given profile may already be
identified without the inclusion of a subject claim.
Note that some SET profiles MAY choose to convey event subject information
in the event payload
(either using the sub member name or another name),
particularly if the subject information is
relative to issuer information that is also conveyed in the event payload,
which may be the case for some identity SET profiles.
As defined by Section 4.1.4 of , this claim
is time after which the JWT MUST NOT be accepted for processing.
In the context of a SET however, this notion does not apply,
since a SET represents something that has already occurred and is historical in nature.
While some profiles MAY choose to use this claim, its use is NOT RECOMMENDED.
The following new claims are defined by this specification:
This claim contains a set of event statements
that each provide information describing a single
logical event that has occurred about a Security Subject
(e.g., a state change to the subject).
Multiple event identifiers with the same value MUST NOT be used.
The events
claim SHOULD NOT be used to express multiple independent logical events.
The value of the events claim is a
JSON object whose members are name/value pairs
whose names are URIs identifying the event statements being
expressed. Event identifiers SHOULD be stable values (e.g., a
permanent URL for an event specification). For each name present,
the corresponding value
MUST be a JSON object. The JSON object MAY be an empty
object ({}), or it MAY be a JSON
object containing data described by the Profiling Specification.
An OPTIONAL string value that represents a unique transaction identifier.
In cases in which multiple related JWTs are issued, the transaction
identifier claim can be used to correlate these related JWTs.
A value that represents the date and time at which the event occurred.
This value is a NumericDate (see Section 2 of ).
This claim is RECOMMENDED.
Note that some profiles may choose to omit toe
and convey event time information with the iat claim or another claim.
This specification registers the application/secevent+jwt
media type, which can be used to indicate that the content is a SET.
SETs MAY include this media type in the typ header parameter
of the JWT representing the SET to explicitly declare that the JWT is a SET.
This MUST be included if the SET could be used in an application context in which
it could be confused with other kinds of JWTs.
Per the definition of typ in Section 4.1.9 of ,
it is RECOMMENDED that the "application/" prefix be omitted.
Therefore, the typ value used SHOULD be
secevent+jwt.
This section describes how to construct a SET.
The JSON Claims Set is encoded per .
For the purpose of having a simpler example in ,
an unsecured token is shown. When SETs are not signed or
encrypted, the Event Recipient MUST employ other mechanisms
such as TLS to provide integrity, confidentiality,
and issuer validation, as needed by the application.
When validation (i.e., auditing), or additional transmission
security is required, JWS signing and/or JWE encryption MAY be used.
To create and or validate a signed and/or encrypted SET, follow
the instructions in Section 7 of .
Profiling Specifications for SETs define the syntax and semantics
of SETs conforming to that SET profile and rules for validating those SETs.
The syntax defined by profiling specifications includes what claims
and event payload values are used by SETs utilizing the profile.
Defining the semantics of the SET contents for SETs utilizing the profile
is equally important.
Possibly most important is defining the procedures used to validate the SET issuer
and to obtain the keys controlled by the issuer that were used for
cryptographic operations used in the JWT representing the SET.
For instance, some profiles may define an algorithm for retrieving
the SET issuer's keys that uses the iss claim value as its input.
Likewise, if the profile allows (or requires) that the JWT be unsecured,
the means by which the integrity of the JWT is ensured MUST be specified.
Profiling Specifications MUST define how the event Subject is identified in the SET,
as well as how to differentiate between the event Subject's Issuer and the SET Issuer, if applicable.
It is NOT RECOMMENDED for Profiling Specifications to use the sub claim
in cases in which the Subject is not globally unique and has a different Issuer from the SET itself.
Among the syntax and semantics of SETs that Profiling Specifications define is
whether and how multiple events values are used
for SETs conforming to those profiles. Many valid choices are possible.
For instance, some profiles might allow multiple event identifiers to be present
and specify that any that are not understood by recipients be ignored,
thus enabling extensibility.
Other profiles might allow multiple event identifiers to be present
but require that all be understood if the SET is to be accepted.
Some profiles might require that only a single value be present.
All such choices are within the scope of Profiling Specifications to define.
Profiling Specifications MUST clearly specify the steps that a recipient of a SET
utilizing that profile MUST perform to validate that the SET is
both syntactically and semantically valid.
SETs may contain sensitive information. Therefore,
methods for distribution of events SHOULD require the use of a
transport-layer security mechanism when distributing events.
Parties MUST support TLS 1.2 and MAY support
additional transport-layer mechanisms meeting its security
requirements. When using TLS, the client MUST perform a TLS/SSL server
certificate check, per . Implementation
security considerations for TLS can be found in "Recommendations for
Secure Use of TLS and DTLS" .Security Events distributed through third parties or that carry personally
identifiable information SHOULD be encrypted using JWE
or secured for confidentiality by other means.
Unless integrity of the JWT is ensured by other means, it
MUST be signed using JWS so
that the SET can be authenticated and validated by the
Event Recipient.This specification does not define a delivery mechanism for SETs.
In addition to confidentiality and integrity (discussed above), implementers
and Profiling Specifications MUST consider the consequences of delivery
mechanisms that are not secure and/or not assured. For example, while
a SET may be end-to-end secured using JWE encrypted SETs, without TLS,
there is no assurance that the correct endpoint received the SET and
that it could be successfully processed.
This specification defines no means of ordering multiple SETs in a sequence.
Depending on the type and nature of the events represented by SETs,
order may or may not matter. For example, in provisioning,
event order is critical -- an object cannot be modified before it
is created. In other SET types, such as a token revocation, the order
of SETs for revoked tokens does not matter. If however, the event conveys
a logged in or logged out status for a user subject, then
order becomes important.Profiling Specifications and implementers SHOULD take caution when
using timestamps such as iat to define order. Distributed systems will have
some amount of clock skew. Thus, time by itself will not guarantee order.Specifications profiling SET SHOULD define a mechanism for detecting
order or sequence of events when the order matters.
For example, the txn
claim could contain an ordered value (e.g., a counter) that the issuer includes.When SETs are delivered asynchronously and/or out-of-band with respect to
the original action that incurred the security event, it is important
to consider that a SET might be delivered to an Event Recipient in advance of
or behind the process that caused the event. For example, a
user having been required to log out and then log back in again, may
cause a logout SET to be issued that may arrive at the same time
as the user agent accesses a web site having just logged in. If
timing is not handled properly, the effect would be to erroneously
treat the new user session as logged out. Profiling Specifications
SHOULD be careful to anticipate timing and subject selection information.
For example, it might be more appropriate to cancel a "session"
rather than a "user". Alternatively, the specification could use timestamps
that allow new sessions to be started immediately after a stated
logout event time.
Because states that "all claims that are not understood
by implementations MUST be ignored", there is a consideration that
a SET might be confused with ID Token
if a SET is mistakenly or intentionally used in a context requiring an ID Token.
If a SET could otherwise be interpreted as a valid ID Token
(because it includes the required claims for an ID Token
and valid issuer and audience claim values for an ID Token)
then that SET profile MUST require that the exp claim
not be present in the SET.
Because exp is a required claim in ID Tokens,
valid ID Token implementations will reject such a SET if presented as if it were an ID Token.
Excluding exp from SETs that
could otherwise be confused with ID Tokens is actually defense in depth.
In any OpenID Connect contexts in which an attacker could attempt to substitute a SET for an ID Token,
the SET would actually already be rejected as an ID Token
because it would not contain the correct nonce claim value
for the ID Token to be accepted in contexts for which substitution is possible.
Note that the use of explicit typing, as described in ,
will not achieve disambiguation between ID Tokens and SETs, as the ID Token validation rules
do not use the typ header parameter value.
OAuth 2.0 defines access tokens as being opaque.
Nonetheless, some implementations implement access tokens as JWTs.
Because the structure of these JWTs is implementation-specific,
ensuring that a SET cannot be confused with such an access token is therefore
likewise, in general, implementation specific.
Nonetheless, it is recommended that SET profiles employ the following strategies
to prevent possible substitutions of SETs for access tokens
in contexts in which that might be possible:
Prohibit use of the exp claim,
as is done to prevent ID Token confusion.
Where possible, use a separate aud
claim value to distinguish between the Event Recipient and the
protected resource that is the audience of an access token.
Modify access token validation systems to check for the presence of
the events claim as a means to detect
security event tokens. This is particularly useful if the same endpoint
may receive both types of tokens.
Employ explicit typing, as described in ,
and modify access token validation systems to use the
typ header parameter value.
JWTs are now being used in application areas beyond the identity applications
in which they first appeared.
For instance, the
Session Initiation Protocol (SIP) Via Header Field
and
Personal Assertion Token (PASSporT)
specifications both define JWT profiles that use mostly or completely different sets of claims
than are used by ID Tokens.
If it would otherwise be possible for an attacker to substitute a SET for one of these (or other)
kinds of JWTs, then the SET profile must be defined in such a way that any substituted SET
will result in its rejection when validated as the intended kind of JWT.
The most direct way to prevent confusion is to
employ explicit typing, as described in ,
and modify applicable token validation systems to use the
typ header parameter value.
This approach can be employed for new systems but may not be applicable to existing systems.
Another way to ensure that a SET is not confused with another kind of JWT
is to have the JWT validation logic reject JWTs containing an events claim
unless the JWT is intended to be a SET.
This approach can be employed for new systems but may not be applicable to existing systems.
For many use cases, the simplest way to prevent substitution is requiring that the SET not include
claims that are required for the kind of JWT that might be the target of an attack.
For example, for ,
the sip_callid claim could be omitted
and for ,
the orig claim could be omitted.
In many contexts, simple measures such as these will accomplish the task,
should confusion otherwise even be possible.
Note that this topic is being explored in a more general fashion in
JSON Web Token Best Current Practices .
The proposed best practices in that draft may also be applicable
for particular SET profiles and use cases.
If a SET needs to be retained for audit purposes, the signature can
be used to provide verification of its authenticity.Event Issuers SHOULD attempt to specialize SETs so that their content
is targeted to the specific business and protocol needs of
the intended Event Recipients.When sharing personally identifiable information or information
that is otherwise considered confidential to affected users, Event
Issuers and Recipients MUST have the appropriate legal agreements
and user consent and/or terms of service in place.The propagation of subject identifiers can be perceived as personally
identifiable information. Where possible, Event Issuers and Recipients
SHOULD devise approaches that prevent propagation -- for example, the
passing of a hash value that requires the Event Recipient to know
the subject.
This specification registers the events,
toe, and
txn claims in the IANA
"JSON Web Token Claims" registry
established by .
Claim Name: events
Claim Description: Security Event URI
Change Controller: IESG
Specification Document(s): of [[ this specification ]]
Claim Name: toe
Claim Description: Time of Event
Change Controller: IESG
Specification Document(s): of [[ this specification ]]
Claim Name: txn
Claim Description: Transaction Identifier
Change Controller: IESG
Specification Document(s): of [[ this specification ]]
This section registers the application/secevent+jwt
media type
in the "Media Types" registry
in the manner described in ,
which can be used to indicate that the content is a SET.
Type name: application
Subtype name: secevent+jwt
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: 8bit;
A SET is a JWT;
JWT values are encoded as a
series of base64url-encoded values (some of which may be the
empty string) separated by period ('.') characters.
Security considerations: See the Security Considerations section of [[ this specification ]]
Interoperability considerations: n/a
Published specification: of [[ this specification ]]
Applications that use this media type:
TBD
Fragment identifier considerations: n/a
Additional information:Magic number(s): n/aFile extension(s): n/aMacintosh file type code(s): n/a
Person & email address to contact for further information:
Michael B. Jones, mbj@microsoft.com
Intended usage: COMMON
Restrictions on usage: none
Author: Michael B. Jones, mbj@microsoft.com
Change controller: IESG
Provisional registration? No
JSON Web Token ClaimsIANAMedia TypesIANAOpenID Connect Core 1.0Nomura Research Institute, Ltd.Ping IdentityMicrosoftGoogleSalesforceAssertions and Protocols for the OASIS Security Assertion Markup Language (SAML) V2.0Internet2OpenID Risk and Incident Sharing and Coordination (RISC) Working GroupOpenID FoundationThe editors would like to thank the members of the IETF SCIM working group, which
began discussions of provisioning events starting with draft-hunt-scim-notify-00 in 2015.The editors would like to thank the participants in the IETF id-event
mailing list, the Security Events working group,
and related working groups for their contributions to this specification.
[[ to be removed by the RFC Editor before publication as an RFC ]]From the original draft-hunt-idevent-token:Draft 01 - PH - Renamed eventUris to eventsDraft 00 - PH - First DraftDraft 01 - PH - Fixed some alignment issues with JWT. Remove event type attribute.Draft 02 - PH - Renamed to Security Events, removed questions, clarified examples and intro text, and added security and privacy section.Draft 03 - PH General edit corrections from Sarah SquireChanged "event" term to "SET"Corrected author organization for William Denniss to GoogleChanged definition of SET to be 2 parts, an envelope and 1 or more payloads.Clarified that the intent is to express a single event with optional extensions only.
- mbj - Registered events claim, and proof-reading corrections.Draft 04 - PH - Re-added the "sub" claim with clarifications that any SET type may use it.Added additional clarification on the use of envelope vs. payload attributesAdded security consideration for event timing.Switched use of "attribute" to "claim" for consistency.Revised examples to put "sub" claim back in the top level.Added clarification that SETs typically do not use "exp".Added security consideration for distinguishing Access Tokens and SETs.Draft 05 - PH - Fixed find/replace error that resulted in claim being spelled claimcDraft 06 - PH - Corrected typosNew txn claimNew security considerations Sequencing and Timing Issues
Draft 07 -
PH - Moved payload objects to be values of event URI attributes, per discussion.mbj - Applied terminology consistency and grammar cleanups.Draft 08 - PH - Added clarification to status of examplesChanged from primary vs. extension to state that multiple
events may be expressed, some of which may or may not
be considered extensions of others (which is for the subscriber
or profiling specifications to determine).Other editorial changes suggested by Yaron From draft-ietf-secevent-token:Draft 00 - PH - First WG Draft based on draft-hunt-idevent-tokenDraft 01 - PH - Changes as follows:Changed terminology away from pub-sub to transmitter/receiver based on WG feedbackCleaned up/removed some text about extensions (now only used as example)Clarify purpose of spec vs. future profiling specs that define actual events
Draft 02 - Changes are as follows:
mbj -
Added the Requirements for SET Profiles section.
mbj -
Expanded the Security Considerations section to describe
how to prevent confusion of SETs with ID Tokens, access tokens,
and other kinds of JWTs.
mbj -
Registered the application/secevent+jwt media type
and defined how to use it for explicit typing of SETs.
mbj -
Clarified the misleading statement that used to say that
a SET conveys a single security event.
mbj -
Added a note explicitly acknowledging that some SET profiles
may choose to convey event subject information in the event payload.
PH -
Corrected encoded claim example on page 10.
mbj -
Applied grammar corrections.
Draft 03 - Changes As Follows:pjh - Corrected old "subscriber" to "Event Receiver". Added clarification
in definition that Event Receiver is the same as JWT recipient.pjh - Added definition for "toe" (and IANA registration).pjh - Removed "nbf" claim.pjh - Figure 3, moved "sub" to the events payload next to "iss".pjh - Clarified the use of "nonce" in contexts where substitution is possible.mbj - Addressed WGLC comments by Nat Sakimura.mbj - Addressed WGLC comments by Annabelle Backman.mbj - Addressed WGLC comments by Marius Scurtescu.
Draft 04 - mbj - Changes were as follows:
Clarified that all "events" values must represent aspects of the same state change
that occurred to the subject -- not an aggregation of unrelated events about the subject.
Removed ambiguities about the roles of multiple "events" values and
the responsibilities of profiling specifications for defining how and when they are used.
Corrected places where the term JWT was used when
what was actually being discussed was the JWT Claims Set.
Addressed terminology inconsistencies. In particular,
standardized on using the term "issuer" to align with JWT terminology and the "iss" claim.
Previously the term "transmitter" was sometimes used and "issuer" was sometimes used.
Likewise, standardized on using the term "recipient" instead of "receiver" for the same reasons.
Added a RISC event example, courtesy of Marius Scurtescu.
Applied wording clarifications suggested by Annabelle Backman and Yaron Sheffer.
Applied numerous grammar, syntax, and formatting corrections.