--- 1/draft-ietf-uta-smtp-tlsrpt-05.txt 2017-05-31 12:13:59.817965729 -0700 +++ 2/draft-ietf-uta-smtp-tlsrpt-06.txt 2017-05-31 12:13:59.861966780 -0700 @@ -1,25 +1,25 @@ Using TLS in Applications D. Margolis Internet-Draft Google, Inc Intended status: Standards Track A. Brotman -Expires: November 4, 2017 Comcast, Inc +Expires: December 01, 2017 Comcast, Inc B. Ramakrishnan Yahoo!, Inc J. Jones Microsoft, Inc M. Risher Google, Inc - May 3, 2017 + May 31, 2017 SMTP TLS Reporting - draft-ietf-uta-smtp-tlsrpt-05 + draft-ietf-uta-smtp-tlsrpt-06 Abstract A number of protocols exist for establishing encrypted channels between SMTP Mail Transfer Agents, including STARTTLS [RFC3207], DANE [RFC6698], and MTA-STS (TODO: Add ref). These protocols can fail due to misconfiguration or active attack, leading to undelivered messages or delivery over unencrypted or unauthenticated channels. This document describes a reporting mechanism and format by which sending systems can share statistics and specific information about potential @@ -35,21 +35,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on November 4, 2017. + This Internet-Draft will expire on November 26, 2017. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -59,47 +59,52 @@ the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Related Technologies . . . . . . . . . . . . . . . . . . . . 4 3. Reporting Policy . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Example Reporting Policy . . . . . . . . . . . . . . . . 5 - 3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 5 + 3.1.1. Report using MAILTO . . . . . . . . . . . . . . . . . 6 3.1.2. Report using HTTPS . . . . . . . . . . . . . . . . . 6 4. Reporting Schema . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Report Time-frame . . . . . . . . . . . . . . . . . . . . 7 4.2. Delivery Summary . . . . . . . . . . . . . . . . . . . . 7 4.2.1. Success Count . . . . . . . . . . . . . . . . . . . . 7 4.2.2. Failure Count . . . . . . . . . . . . . . . . . . . . 7 4.3. Result Types . . . . . . . . . . . . . . . . . . . . . . 7 4.3.1. Negotiation Failures . . . . . . . . . . . . . . . . 7 4.3.2. Policy Failures . . . . . . . . . . . . . . . . . . . 8 4.3.3. General Failures . . . . . . . . . . . . . . . . . . 8 - 4.3.4. Transient Failures . . . . . . . . . . . . . . . . . 8 - 5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 9 - 5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 9 - 5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 9 - 5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 10 - 5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 10 - 5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 11 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 - 8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 12 - 8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 12 - 8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 12 - 9. Appendix 2: JSON Report Schema . . . . . . . . . . . . . . . 12 - 10. Appendix 3: Example JSON Report . . . . . . . . . . . . . . . 15 - 11. Normative References . . . . . . . . . . . . . . . . . . . . 16 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 + 4.3.4. Transient Failures . . . . . . . . . . . . . . . . . 9 + 4.4. JSON Report Schema . . . . . . . . . . . . . . . . . . . 9 + 5. Report Delivery . . . . . . . . . . . . . . . . . . . . . . . 11 + 5.1. Report Filename . . . . . . . . . . . . . . . . . . . . . 11 + 5.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 12 + 5.3. Email Transport . . . . . . . . . . . . . . . . . . . . . 12 + 5.3.1. Example Report . . . . . . . . . . . . . . . . . . . 13 + 5.4. HTTPS Transport . . . . . . . . . . . . . . . . . . . . . 14 + 5.5. Delivery Retry . . . . . . . . . . . . . . . . . . . . . 14 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 + 6.1. Message headers . . . . . . . . . . . . . . . . . . . . . 15 + 6.2. Report Type . . . . . . . . . . . . . . . . . . . . . . . 15 + 6.3. application/tlsrpt+* Media Types . . . . . . . . . . . . 15 + 6.4. STARTTLS Validation Result Types . . . . . . . . . . . . 16 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17 + 8. Appendix 1: Example Reporting Policy . . . . . . . . . . . . 18 + 8.1. Report using MAILTO . . . . . . . . . . . . . . . . . . . 18 + 8.2. Report using HTTPS . . . . . . . . . . . . . . . . . . . 18 + 9. Appendix 2: Example JSON Report . . . . . . . . . . . . . . . 18 + 10. Normative References . . . . . . . . . . . . . . . . . . . . 20 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 1. Introduction The STARTTLS extension to SMTP [RFC3207] allows SMTP clients and hosts to establish secure SMTP sessions over TLS. The protocol design is based on "Opportunistic Security" (OS) [RFC7435], which maintains interoperability with clients that do not support STARTTLS but means that any attacker who can delete parts of the SMTP session (such as the "250 STARTTLS" response) or redirect the entire SMTP session (perhaps by overwriting the resolved MX record of the @@ -146,26 +151,26 @@ MTAs should deliver reports. o Policy Domain: The domain against which an MTA-STS or DANE Policy is defined. o Sending MTA: The MTA initiating the delivery of an email message. 2. Related Technologies o This document is intended as a companion to the specification for - SMTP MTA Strict Transport Security (MTA-STS, TODO: Add ref). + SMTP MTA Strict Transport Security (MTA-STS, TODO: Add RFC ref). o SMTP-TLSRPT defines a mechanism for sending domains that are compatible with MTA-STS or DANE to share success and failure statistics with recipient domains. DANE is defined in [RFC6698] - and MTA-STS is defined in [TODO] + and MTA-STS is defined in [TODO : Add RFC ref] 3. Reporting Policy A domain publishes a record to its DNS indicating that it wishes to receive reports. These SMTP TLSRPT policies are distributed via DNS from the Policy Domain's zone, as TXT records (similar to DMARC policies) under the name "_smtp-tlsrpt". For example, for the Policy Domain "example.com", the recipient's TLSRPT policy can be retrieved from "_smtp-tlsrpt.example.com". @@ -342,43 +346,146 @@ o "tlsa-invalid": This indicates a validation error in the TLSA record associated with a DANE policy. None of the records in the RRset were found to be valid. o "dnssec-invalid": This would indicate that no valid records were returned from the recursive resolver. The request returned with SERVFAIL for the requested TLSA record. 4.3.2.2. MTA-STS-specific Policy Failures - o "sts-invalid": This indicates a validation error for the overall - MTA-STS policy. + o "sts-policy-invalid": This indicates a validation error for the + overall MTA-STS policy. - o "webpki-invalid": This indicates that the MTA-STS policy could not - be authenticated using PKIX validation. + o "sts-webpki-invalid": This indicates that the MTA-STS policy could + not be authenticated using PKIX validation. 4.3.3. General Failures When a negotiation failure can not be categorized into one of the "Negotiation Failures" stated above, the reporter SHOULD use the "validation-failure" category. As TLS grows and becomes more complex, new mechanisms may not be easily categorized. This allows for a generic feedback category. When this category is used, the reporter SHOULD also use the "failure-reason-code" to give some feedback to the receiving entity. This is intended to be a short text field, and the contents of the field should be an error code or error text, such as "X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION". 4.3.4. Transient Failures Transient errors due to too-busy network, TCP timeouts, etc. are not required to be reported. +4.4. JSON Report Schema + + The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf. + Section 3) + + { + "organization-name": organization-name, + "date-range": { + "start-datetime": date-time, + "end-datetime": date-time + }, + "contact-info": email-address, + "report-id": report-id, + "policy": { + "policy-type": policy-type, + "policy-string": policy-string, + "policy-domain": domain, + "mx-host": mx-host-pattern + }, + "summary": { + "success-aggregate": total-successful-session-count, + "failure-aggregate:" total-failure-session-count + } + "failure-details": [ + { + "result-type": result-type, + "sending-mta-ip": ip-address, + "receiving-mx-hostname": receiving-mx-hostname, + "receiving-mx-helo": receiving-mx-helo, + "session-count": failed-session-count, + "additional-information": additional-info-uri, + "failure-reason-code": "Text body" + } + ] + } + + JSON Report Format + + o "organization-name": The name of the organization responsible for + the report. It is provided as a string. + + o "date-time": The date-time indicates the start- and end-times for + the report range. It is provided as a string formatted according + to Section 5.6, "Internet Date/Time Format", of [RFC3339]. The + report should be for a full UTC day, 0000-2400. + + o "email-address": The contact information for a responsible party + of the report. It is provided as a string formatted according to + Section 3.4.1, "Addr-Spec", of [RFC5322]. + + o "report-id": A unique identifier for the report. Report authors + may use whatever scheme they prefer to generate a unique + identifier. It is provided as a string. + + o "policy-type": The type of policy that was applied by the sending + domain. Presently, the only three valid choices are "tlsa", + "sts", and the literal string "no-policy-found". It is provided + as a string. + + o "policy-string": The JSON string serialization ([RFC7159] section + 7) of the policy, whether TLSA record ([RFC6698] section 2.3) or + MTA-STS policy. + + o "domain": The Policy Domain is the domain against which the MTA- + STS or DANE policy is defined. + + o "mx-host-pattern": The pattern of MX hostnames from the applied + policy. It is provided as a string, and is interpreted in the + same manner as the "Checking of Wildcard Certificates" rules in + Section 6.4.3 of [RFC6125]. + + o "result-type": A value from Section 4.3, "Result Types", above. + + o "ip-address": The IP address of the sending MTA that attempted the + STARTTLS connection. It is provided as a string representation of + an IPv4 or IPv6 address in dot-decimal or colon-hexadecimal + notation. + + o "receiving-mx-hostname": The hostname of the receiving MTA MX + record with which the sending MTA attempted to negotiate a + STARTTLS connection. + + o "receiving-mx-helo": (optional) The HELO or EHLO string from the + banner announced during the reported session. + + o "success-aggregate": The aggregate number (integer) of + successfully negotiated TLS-enabled connections to the receiving + site. + + o "failure-aggregate": The aggregate number (integer) of failures to + negotiate an TLS-enabled connection to the receiving site. + + o "session-count": The number of (attempted) sessions that match the + relevant "result-type" for this section. + + o "additional-info-uri": An optional URI pointing to additional + information around the relevant "result-type". For example, this + URI might host the complete certificate chain presented during an + attempted STARTTLS session. + + o "failure-reason-code": A text field to include an TLS-related + error code or error message. + 5. Report Delivery Reports can be delivered either as an email message via SMTP or via HTTP POST. 5.1. Report Filename The filename is typically constructed using the following ABNF: filename = sender "!" policy-domain "!" begin-timestamp @@ -416,28 +523,44 @@ 5.2. Compression The report SHOULD be subjected to GZIP compression for both email and HTTPS transport. Declining to apply compression can cause the report to be too large for a receiver to process (a commonly observed receiver limit is ten megabytes); compressing the file increases the chances of acceptance of the report at some compute cost. 5.3. Email Transport - The report MAY be delivered by email. No specific MIME message - structure is required. It is presumed that the aggregate reporting - address will be equipped to extract MIME parts with the prescribed - media type and filename and ignore the rest. + The report MAY be delivered by email. To make the reports machine- + parsable for the receivers, we define a top-level media type + "multipart/report" with a new parameter "report-type="tlsrpt"". + Inside it, there are two parts: The first part is human readable, + typically "text/plain", and the second part is machine readable with + a new media type defined called "application/tlsrpt+json". If + compressed, the report should use the media type "application/ + tlsrpt+gzip". - If compressed, the report should use the media type "application/ - gzip" if compressed (see [RFC6713]), and "application/json" - otherwise. + In addition, the following two new top level message header fields + are defined: + + TLS-Report-Domain: Receiver-Domain + TLS-Report-Submitter: Sender-Domain + + These message headers would allow for easy searching for all reports + submitted by a report domain or a particular submitter, for example + in IMAP: + + "s SEARCH HEADER "TLS-Report-Domain" "example.com"" + + It is presumed that the aggregate reporting address will be equipped + to process new message header fields and extract MIME parts with the + prescribed media type and filename, and ignore the rest. The [RFC5322].Subject field for individual report submissions SHOULD conform to the following ABNF: tlsrpt-subject = %x52.65.70.6f.72.74 1*FWS ; "Report" %x44.6f.6d.61.69.6e.3a 1*FWS ; "Domain:" domain-name 1*FWS ; from RFC 6376 %x53.75.62.6d.69.74.74.65.72.3a ; "Submitter:" 1*FWS domain-name 1*FWS %x52.65.70.6f.72.74.2d.49.44.3a ; "Report-ID:" @@ -452,196 +575,237 @@ For instance, this is a possible Subject field for a report to the Policy Domain "example.net" from the Sending MTA "mail.sender.example.com". It is line-wrapped as allowed by [RFC5322]: Subject: Report Domain: example.net Submitter: mail.sender.example.com Report-ID: <735ff.e317+bf22029@mailexample.net> +5.3.1. Example Report + From: tlsrpt@mail.sender.example.com + Date: Fri, May 09 2017 16:54:30 -0800 + To: mts-sts-tlsrpt@example.net + Subject: Report Domain: example.net + Submitter: mail.sender.example.com + Report-ID: <735ff.e317+bf22029@example.net> + TLS-Report-Domain: example.net + TLS-Report-Submitter: mail.sender.example.com + MIME-Version: 1.0 + Content-Type: multipart/report; report-type="tlsrpt"; + boundary="----=_NextPart_000_024E_01CC9B0A.AFE54C00" + Content-Language: en-us + + This is a multipart message in MIME format. + + ------=_NextPart_000_024E_01CC9B0A.AFE54C00 + Content-Type: text/plain; charset="us-ascii" + Content-Transfer-Encoding: 7bit + + This is an aggregate TLS report from mail.sender.example.com + + ------=_NextPart_000_024E_01CC9B0A.AFE54C00 + Content-Type: application/tlsrpt+gzip + Content-Transfer-Encoding: base64 + Content-Disposition: attachment; + filename="mail.sender.example!example.com! + 1013662812!1013749130.gz" + + + + ------=_NextPart_000_024E_01CC9B0A.AFE54C00-- + ... + Note that, when sending failure reports via SMTP, sending MTAs MUST NOT honor MTA-STS or DANE TLSA failures. 5.4. HTTPS Transport The report MAY be delivered by POST to HTTPS. If compressed, the - report should use the media type "application/gzip" (see [RFC6713]), - and "application/json" otherwise. + report should use the media type "application/tlsrpt+gzip", and + "application/tlsrpt+json" otherwise (see section Section 6, "IANA + Considerations"). 5.5. Delivery Retry In the event of a delivery failure, regardless of the delivery method, a sender SHOULD attempt redelivery for up to 24hrs after the initial attempt. As previously stated the reports are optional, so while it is ideal to attempt redelivery, it is not required. If multiple retries are attempted, they should be on a logarithmic scale. 6. IANA Considerations - There are no IANA considerations at this time. + The following are the IANA considerations discussed in this document. + +6.1. Message headers + + Below is the Internet Assigned Numbers Authority (IANA) Permanent + Message Header Field registration information per [RFC3864]. + + Header field name: TLS-Report-Domain + Applicable protocol: smtp + Status: standard + Author/Change controller: IETF + Specification document(s): this one + + Header field name: TLS-Report-Submitter + Applicable protocol: smtp + Status: standard + Author/Change controller: IETF + Specification document(s): this one + +6.2. Report Type + + This document registers a new parameter "report-type="tlsrpt"" under + "multipart/report" top-level media type for use with [RFC6522]. + + The media type suitable for use as a report-type is defined in the + following section. + +6.3. application/tlsrpt+* Media Types + + This document registers multiple media types, listed in Table 1 + below. + + +-------------+----------------+-------------+-------------------+ + | Type | Subtype | File extn | Specification | + +-------------+----------------+-------------+-------------------+ + | application | tlsrpt+json | .json | Section 5.3 | + | application | tlsrpt+gzip | .gz | Section 5.3 | + +-------------+----------------+-------------+-------------------+ + Table 1: SMTP TLS Reporting Media Types + + Type name: application + Subtype name: This documents registers multiple subtypes, as listed + in Table 1. + + Required parameters: n/a + + Optional parameters: n/a + + Encoding considerations: Encoding considerations are identical to + those specified for the "application/json" media type. See + [RFC7159]. + + Security considerations: Security considerations relating to SMTP TLS + Reporting are discussed in Section 7. + + Interoperability considerations: This document specifies format of + conforming messages and the interpretation thereof. + + Published specification: This document is the specification for these + media types; see Table 1 for the section documenting each media type. + + Applications that use this media type: Mail User Agents (MUA) and + Mail Transfer Agents. + + Additional information: + + Magic number(s): n/a + + File extension(s): As listed in Table 1. + + Macintosh file type code(s): n/a + + Person & email address to contact for further information: See + Authors' Addresses section. + + Intended usage: COMMON + + Restrictions on usage: n/a + + Author: See Authors' Addresses section. + + Change controller: Internet Engineering Task Force + (mailto:iesg@ietf.org). + +6.4. STARTTLS Validation Result Types + + This document creates a new registry, "STARTTLS Validation Result + Types". The initial entries in the registry are: + + +-------------------------------+ + | Result Type | + +-------------------------------+ + | "starttls-not-supported" | + | "certificate-host-mismatch" | + | "certificate-expired" | + | "tlsa-invalid" | + | "dnssec-invalid" | + | "sts-policy-invalid" | + | "sts-webpki-invalid" | + | "validation-failure" | + +-------------------------------+ + + The above entries are described in section Section 4.3, "Result + Types." New result types can be added to this registry without the + need to update this document. 7. Security Considerations SMTP TLS Reporting provides transparency into misconfigurations or attempts to intercept or tamper with mail between hosts who support STARTTLS. There are several security risks presented by the existence of this reporting channel: o Flooding of the Aggregate report URI (rua) endpoint: An attacker - could flood the endpoint and prevent the receiving domain from - accepting additional reports. This type of Denial-of-Service - attack would limit visibility into STARTTLS failures, leaving the - receiving domain blind to an ongoing attack. + could flood the endpoint with excessive reporting traffic and + prevent the receiving domain from accepting additional reports. + This type of Denial-of-Service attack would limit visibility into + STARTTLS failures, leaving the receiving domain blind to an + ongoing attack. o Untrusted content: An attacker could inject malicious code into the report, opening a vulnerability in the receiving domain. Implementers are advised to take precautions against evaluating the contents of the report. o Report snooping: An attacker could create a bogus TLSRPT record to receive statistics about a domain the attacker does not own. Since an attacker able to poison DNS is already able to receive counts of SMTP connections (and, absent DANE or MTA-STS policies, actual SMTP message payloads), this does not present a significant new vulnerability. o Reports as DDoS: TLSRPT allows specifying destinations for the reports that are outside the authority of the Policy Domain, which allows domains to delegate processing of reports to a partner organization. However, an attacker who controls the Policy Domain DNS could also use this mechanism to direct the reports to an unwitting victim, flooding that victim with excessive reports. - DMARC [RFC7489] defines an elegant solution for verifying - delegation; however, since the attacker had less ability to - generate large reports than with DMARC failures, and since the - reports are generated by the sending MTA, such a delegation - mechanism is left for a future version of this specification. + DMARC [RFC7489] defines a solution for verifying delegation to + avoid such attacks; the need for this is greater with DMARC, + however, because DMARC allows an attacker to trigger reports to a + target from an innocent third party by sending that third party + mail (which triggers a report from the third party to the target). + In the case of TLSRPT, the attacker would have to induce the third + party to send the attacker mail in order to trigger reports from + the third party to the victim; this reduces the risk of such an + attack and the need for a verification mechanism. 8. Appendix 1: Example Reporting Policy 8.1. Report using MAILTO _smtp-tlsrpt.mail.example.com. IN TXT \ "v=TLSRPTv1;rua=mailto:reports@example.com" 8.2. Report using HTTPS _smtp-tlsrpt.mail.example.com. IN TXT \ "v=TLSRPTv1; \ rua=https://reporting.example.com/v1/tlsrpt" -9. Appendix 2: JSON Report Schema - - The JSON schema is derived from the HPKP JSON schema [RFC7469] (cf. - Section 3) - { - "organization-name": organization-name, - "date-range": { - "start-datetime": date-time, - "end-datetime": date-time - }, - "contact-info": email-address, - "report-id": report-id, - "policy": { - "policy-type": policy-type, - "policy-string": policy-string, - "policy-domain": domain, - "mx-host": mx-host-pattern - }, - "summary": { - "success-aggregate": total-successful-session-count, - "failure-aggregate:" total-failure-session-count - } - "failure-details": [ - { - "result-type": result-type, - "sending-mta-ip": ip-address, - "receiving-mx-hostname": receiving-mx-hostname, - "receiving-mx-helo": receiving-mx-helo, - "session-count": failed-session-count, - "additional-information": additional-info-uri, - "failure-reason-code": "Text body" - } - ] - } - - Figure: JSON Report Format - - o "organization-name": The name of the organization responsible for - the report. It is provided as a string. - - o "date-time": The date-time indicates the start- and end-times for - the report range. It is provided as a string formatted according - to Section 5.6, "Internet Date/Time Format", of [RFC3339]. The - report should be for a full UTC day, 0000-2400. - - o "email-address": The contact information for a responsible party - of the report. It is provided as a string formatted according to - Section 3.4.1, "Addr-Spec", of [RFC5322]. - - o "report-id": A unique identifier for the report. Report authors - may use whatever scheme they prefer to generate a unique - identifier. It is provided as a string. - - o "policy-type": The type of policy that was applied by the sending - domain. Presently, the only three valid choices are "tlsa", - "sts", and the literal string "no-policy-found". It is provided - as a string. - - o "policy-string": The JSON string serialization ([RFC7159] section - 7) of the policy, whether TLSA record ([RFC6698] section 2.3) or - MTA-STS policy. - - o "domain": The Policy Domain is the domain against which the MTA- - STS or DANE policy is defined. - - o "mx-host-pattern": The pattern of MX hostnames from the applied - policy. It is provided as a string, and is interpreted in the - same manner as the "Checking of Wildcard Certificates" rules in - Section 6.4.3 of [RFC6125]. - - o "result-type": A value from Section 4.3, "Result Types", above. - - o "ip-address": The IP address of the sending MTA that attempted the - STARTTLS connection. It is provided as a string representation of - an IPv4 or IPv6 address in dot-decimal or colon-hexadecimal - notation. - - o "receiving-mx-hostname": The hostname of the receiving MTA MX - record with which the sending MTA attempted to negotiate a - STARTTLS connection. - - o "receiving-mx-helo": (optional) The HELO or EHLO string from the - banner announced during the reported session. - - o "success-aggregate": The aggregate number (integer) of - successfully negotiated TLS-enabled connections to the receiving - site. - - o "failure-aggregate": The aggregate number (integer) of failures to - negotiate an TLS-enabled connection to the receiving site. - - o "session-count": The number of (attempted) sessions that match the - relevant "result-type" for this section. - - o "additional-info-uri": An optional URI pointing to additional - information around the relevant "result-type". For example, this - URI might host the complete certificate chain presented during an - attempted STARTTLS session. - - o "failure-reason-code": A text field to include an TLS-related - error code or error message. - -10. Appendix 3: Example JSON Report - +9. Appendix 2: Example JSON Report { "organization-name": "Company-X", "date-range": { "start-datetime": "2016-04-01T00:00:00Z", "end-datetime": "2016-04-01T23:59:59Z" }, "contact-info": "sts-reporting@company-x.com", "report-id": "5065427c-23d3-47ca-b6e0-946ea0e8c4be", "policy": { "policy-type": "sts", @@ -674,68 +838,74 @@ }] } Figure: Example JSON report for a messages from Company-X to Company-Y, where 100 sessions were attempted to Company Y servers with an expired certificate and 200 sessions were attempted to Company Y servers that did not successfully respond to the "STARTTLS" command. Additionally 3 sessions failed due to "X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED". -11. Normative References +10. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March 1997, . [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/ RFC2818, May 2000, . [RFC3207] Hoffman, P., "SMTP Service Extension for Secure SMTP over Transport Layer Security", RFC 3207, DOI 10.17487/RFC3207, February 2002, . [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, . + [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration + Procedures for Message Header Fields", BCP 90, RFC 3864, + DOI 10.17487/RFC3864, September 2004, + . + [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/ RFC5234, January 2008, . [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI 10.17487/RFC5322, October 2008, . [RFC6068] Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto' URI Scheme", RFC 6068, DOI 10.17487/RFC6068, October 2010, . [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 2011, . + [RFC6522] Kucherawy, M., Ed., "The Multipart/Report Media Type for + the Reporting of Mail System Administrative Messages", STD + 73, RFC 6522, DOI 10.17487/RFC6522, January 2012, + . + [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 2012, . - [RFC6713] Levine, J., "The 'application/zlib' and 'application/gzip' - Media Types", RFC 6713, DOI 10.17487/RFC6713, August 2012, - . - [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014, . [RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection Most of the Time", RFC 7435, DOI 10.17487/RFC7435, December 2014, . [RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April