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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force C. Lonvick 3 Internet-Draft 4 Updates: 5425 6012 (if approved) S. Turner 5 Intended status: Standards Track sn3rd 6 Expires: 13 June 2022 J. Salowey 7 Salesforce 8 10 December 2021 10 Updates to the Cipher Suites in Secure Syslog 11 draft-ciphersuites-in-sec-syslog-00 13 Abstract 15 This document updates the cipher suites in RFC 5425, Transport Layer 16 Security (TLS) Transport Mapping for Syslog, and RFC 6012, Datagram 17 Transport Layer Security (DTLS) Transport Mapping for Syslog. It 18 also updates the transport protocol in RFC 6012. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on 13 June 2022. 37 Copyright Notice 39 Copyright (c) 2021 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 44 license-info) in effect on the date of publication of this document. 45 Please review these documents carefully, as they describe your rights 46 and restrictions with respect to this document. Code Components 47 extracted from this document must include Revised BSD License text as 48 described in Section 4.e of the Trust Legal Provisions and are 49 provided without warranty as described in the Revised BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Support for Updating . . . . . . . . . . . . . . . . . . . . 3 56 4. Updates to RFC 5425 . . . . . . . . . . . . . . . . . . . . . 4 57 5. Updates to RFC 6012 . . . . . . . . . . . . . . . . . . . . . 4 58 6. Authors Notes . . . . . . . . . . . . . . . . . . . . . . . . 4 59 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 60 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 61 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 62 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 64 10.2. Informative References . . . . . . . . . . . . . . . . . 7 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 67 1. Introduction 69 The Syslog Working Group produced Transport Layer Security (TLS) 70 Transport Mapping for Syslog [RFC5425] and Datagram Transport Layer 71 Security (DTLS) Transport Mapping for Syslog [RFC6012]. 73 Both [RFC5425] and [RFC6012] MUST support certificates as defined in 74 [RFC5280]. 76 [RFC5425] requires that implementations "MUST" support TLS 1.2 77 [RFC5246] and are "REQUIRED" to support the mandatory to implement 78 cipher suite TLS_RSA_WITH_AES_128_CBC_SHA (Section 4.2). 80 [RFC6012] requires that implementations "MUST" support DTLS 1.0 81 [RFC4347] and are also "REQUIRED" to support the mandatory to 82 implement cipher suite TLS_RSA_WITH_AES_128_CBC_SHA (Section 5.2). 84 The TLS_RSA_WITH_AES_128_CBC_SHA cipher suite has been found to be 85 weak and the community is moving away from it and towards more robust 86 suites. 88 The DTLS 1.0 transport [RFC4347] has been deprecated and the 89 community is moving to DTLS 1.2 [RFC6347]. 91 This document updates [RFC5425] and [RFC6012] to deprecate the use of 92 TLS_RSA_WITH_AES_128_CBC_SHA and to make new recommendations to a 93 mandatory to implement cipher suite to be used for implementations. 94 This document also updates [RFC6012] to deprecate the use of DTLS 1.0 95 and to make a recommendation of a mandatory to implement secure 96 datagram transport. 98 2. Terminology 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in 103 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 104 capitals, as shown here. 106 3. Support for Updating 108 [I-D.salowey-tls-rfc8447bis] generally reminds us that cryptographic 109 algorithms and parameters will be broken or weakened over time. 110 Blindly implementing the cryptographic algorithms listed in any 111 specification is not advised. Implementers and users need to check 112 that the cryptographic algorithms specified continue to provide the 113 expected level of security. 115 As the Syslog Working Group determined, Syslog clients and servers 116 MUST use certificates as defined in [RFC5280]. Since both [RFC5425] 117 and [RFC6012] REQUIRE the use of TLS_RSA_WITH_AES_128_CBC_SHA, it is 118 very likely that RSA certificates have been implemented in devices 119 adhering to those specifications. [BCP195] notes that ECDHE cipher 120 suites exist for both RSA and ECDSA certificates, so moving to an 121 ECDHE cipher suite will not require replacing or moving away from any 122 currently installed RSA-based certificates. 124 [I-D.saviram-tls-deprecate-obsolete-kex] documents that the cipher 125 suite TLS_RSA_WITH_AES_128_CBC_SHA has been found to be weak. As 126 such, the community is moving away from that and other weak suites 127 and towards more robust suites such as 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, which is also listed as a 129 currently Recommended algorithm in [I-D.salowey-tls-rfc8447bis]. 131 Along those lines, [I-D.ietf-uta-rfc7525bis] notes that 132 TLS_RSA_WITH_AES_128_CBC_SHA does not provide forward secrecy, a 133 feature that is highly desirable in securing event messages. That 134 document also goes on to recommend 135 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 as a cipher suite that does 136 provide forward secrecy. 138 Therefore, the mandatory to implement cipher suites listed in 139 [RFC5425] and [RFC6012] must be updated so that implementations of 140 secure syslog are still considered to provide an acceptable and 141 expected level of security. 143 Additionally, [BCP195] [RFC8996] deprecates the use of DTLS 1.0 144 [RFC4347], which is the mandatory to implement transport protocol for 145 [RFC6012]. Therefore, the transport protocol for [RFC6012] must be 146 updated. 148 4. Updates to RFC 5425 150 Implementations of [RFC5425] MUST NOT offer 151 TLS_RSA_WITH_AES_128_CBC_SHA. The mandatory to implement cipher 152 suite is REQUIRED to be TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. 154 Implementations of [RFC5425] MUST continue to use TLS 1.2 [RFC5246] 155 as the mandatory to implement transport protocol. 157 Implementations of [RFC5425] MAY use TLS 1.3 [RFC8446] as a transport 158 as long as they support the currently recommended cipher suites. 160 EDITOR's NOTE: Need to address 0-RTT considerations. 162 5. Updates to RFC 6012 164 Implementations of [RFC6012] MUST NOT offer 165 TLS_RSA_WITH_AES_128_CBC_SHA. The mandatory to implement cipher 166 suite is REQUIRED to be TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. 168 Implementations of [RFC6012] MUST NOT use DTLS 1.0 [RFC4347]. 169 Implementations MUST use DTLS 1.2 [RFC6347]. 171 DTLS 1.2 [RFC6347] implementations are REQUIRED to support the 172 mandatory to implement cipher suite, which is 173 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. 175 Implementations of [RFC6012] MAY use DTLS 1.3 [I-D.ietf-tls-dtls13] 176 as a transport as long as they support the currently recommended 177 cipher suites. 179 EDITOR's NOTE: Need to address 0-RTT considerations. 181 6. Authors Notes 183 This section will be removed prior to publication. 185 This is version -00. Comments welcome. 187 Some members of the now closed Syslog Working Group were recently 188 contacted by a member of the IEC 62351 TC 57 WG15 with the following 189 message: 191 | For the development of an IEC cybersecurity standard for 192 | electrical power system, we (WG15) are trying to reference RFC 193 | 5425 and adopt its specifications. However, since RFC 5425 194 | specifies TLS_RSA_WITH_AES_128_CBC_SHA, which is currently 195 | insecure and depreciated cipher suite. Therefore, we are trying 196 | to adopt stronger cipher suites in accordance with IEC 62351-3. 197 | IEC 62351-3 specifies a set of stronger state of the art cipher 198 | suites and thus defines a profile on how to apply TLS, addressing 199 | authentication, cipher suite requirements, renegotiation, etc. 200 | Therefore, we would like to use the state of the art cipher suites 201 | as specified in IEC 62351-3 and also mandatorily refer RFC 5425 202 | including the usage of its port number 6514 for transporting 203 | secure syslog traffic. Our understanding would be that it does 204 | not violate RFC 5425, as it allows in section 4.2 of RFC 5425 that 205 | also stronger cipher suites may be used. 207 This prompted the authors of this specification to draft it and 208 propose it as an RFC. 210 WG15 has also proposed the following text to be inserted into their 211 documents. 213 | The selection of TLS connection parameters such as cipher suites, 214 | session resumption and renegotiation shall be reused from IEC 215 | 62351-3 specification. Note that port TCP/6514 is assigned by 216 | IANA to RFC 5425 (syslog-tls). The RFC requires the support of 217 | TLS1.2 and a SHA-1 based cipher suite, but does not mandate its 218 | use. The cipher does not align with IEC 62351-3 Ed.2 for 219 | profiling TLS. Nevertheless, RFC 5425 does not rule out to use 220 | stronger cipher suites. With this, clients and server supporting 221 | the selection of cipher suites stated in IEC 62351-3 Ed2 will not 222 | experience interoperability problems. Caution has to be taken in 223 | environments in which interworking with existing services 224 | utilizing syslog over TLS is intended. For these, the syslog 225 | server needs to be enabled to support the required cipher suites. 226 | This ensures connectivity with clients complying to this document 227 | and others complying to RFC 5425. Note that meanwhile the work on 228 | an update of RFC 5425 and RFC 6012 has started. It targets the 229 | adoption of stronger cipher suites for TLS and DTLS to protect 230 | syslog communication. 232 Comments on this text are also welcome. 234 7. Acknowledgments 236 The authors would like to thank Arijit Kumar Bose, Steffen Fries and 237 the members of IEC TC57 WG15 for their review, comments, and 238 suggestions. 240 8. IANA Considerations 242 This document makes no requests to IANA. 244 9. Security Considerations 246 This document deprecates an insecure DTLS transport protocol from 247 [RFC6012] and deprecates insecure cipher suits from [RFC5425] and 248 [RFC6012]. This document also specifies mandatory to implement 249 cipher suites to those RFCs and the latest version of the DTLS 250 protocol to [RFC6012]. 252 10. References 254 10.1. Normative References 256 [BCP14] Bradner, S., "Key words for use in RFCs to Indicate 257 Requirement Levels", BCP 14, RFC 2119, March 1997. 259 Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 260 2119 Key Words", BCP 14, RFC 8174, May 2017. 262 264 [BCP195] Sheffer, Y., Holz, R., and P. Saint-Andre, 265 "Recommendations for Secure Use of Transport Layer 266 Security (TLS) and Datagram Transport Layer Security 267 (DTLS)", BCP 195, RFC 7525, May 2015. 269 Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS 270 1.1", BCP 195, RFC 8996, March 2021. 272 274 [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 275 Security", RFC 4347, DOI 10.17487/RFC4347, April 2006, 276 . 278 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 279 (TLS) Protocol Version 1.2", RFC 5246, 280 DOI 10.17487/RFC5246, August 2008, 281 . 283 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 284 Housley, R., and W. Polk, "Internet X.509 Public Key 285 Infrastructure Certificate and Certificate Revocation List 286 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 287 . 289 [RFC5425] Miao, F., Ed., Ma, Y., Ed., and J. Salowey, Ed., 290 "Transport Layer Security (TLS) Transport Mapping for 291 Syslog", RFC 5425, DOI 10.17487/RFC5425, March 2009, 292 . 294 [RFC6012] Salowey, J., Petch, T., Gerhards, R., and H. Feng, 295 "Datagram Transport Layer Security (DTLS) Transport 296 Mapping for Syslog", RFC 6012, DOI 10.17487/RFC6012, 297 October 2010, . 299 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 300 Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, 301 January 2012, . 303 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 304 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 305 . 307 10.2. Informative References 309 [I-D.ietf-tls-dtls13] 310 Rescorla, E., Tschofenig, H., and N. Modadugu, "The 311 Datagram Transport Layer Security (DTLS) Protocol Version 312 1.3", Work in Progress, Internet-Draft, draft-ietf-tls- 313 dtls13, 30 April 2021, 314 . 317 [I-D.ietf-uta-rfc7525bis] 318 Sheffer, Y., Holz, R., Saint-Andre, P., and T. Fossati, 319 "Recommendations for Secure Use of Transport Layer 320 Security (TLS) and Datagram Transport Layer Security 321 (DTLS)", Work in Progress, Internet-Draft, draft-ietf-uta- 322 rfc7525bis-04, 2 December 2021, 323 . 326 [I-D.salowey-tls-rfc8447bis] 327 Salowey, J. and S. Turner, "IANA Registry Updates for TLS 328 and DTLS", Work in Progress, Internet-Draft, draft- 329 salowey-tls-rfc8447bis-01, 2 December 2021, 330 . 333 [I-D.saviram-tls-deprecate-obsolete-kex] 334 Aviram, N., "Deprecating Obsolete Key Exchange Methods in 335 TLS", Work in Progress, Internet-Draft, draft-aviram-tls- 336 deprecate-obsolete-kex-00, 9 July 2021, 337 . 340 Authors' Addresses 342 Chris Lonvick 344 Email: lonvick.ietf@gmail.com 346 Sean Turner 347 sn3rd 349 Email: sean@sn3rd.com 351 Joe Salowey 352 Salesforce 354 Email: joe@salowey.net