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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 4347 (Obsoleted by RFC 6347) -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) -- Obsolete informational reference (is this intentional?): RFC 6347 (Obsoleted by RFC 9147) == Outdated reference: A later version (-11) exists of draft-ietf-uta-tls-bcp-05 == Outdated reference: A later version (-01) exists of draft-ietf-tls-prohibiting-rc4-00 == Outdated reference: A later version (-10) exists of draft-ietf-tls-negotiated-ff-dhe-02 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 uta Y. Sheffer 3 Internet-Draft Porticor 4 Intended status: Informational R. Holz 5 Expires: April 26, 2015 TUM 6 P. Saint-Andre 7 &yet 8 October 23, 2014 10 Summarizing Known Attacks on TLS and DTLS 11 draft-ietf-uta-tls-attacks-05 13 Abstract 15 Over the last few years there have been several serious attacks on 16 Transport Layer Security (TLS), including attacks on its most 17 commonly used ciphers and modes of operation. This document 18 summarizes these attacks, with the goal of motivating generic and 19 protocol-specific recommendations on the usage of TLS and Datagram 20 TLS (DTLS). 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on April 26, 2015. 39 Copyright Notice 41 Copyright (c) 2014 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Attacks on TLS . . . . . . . . . . . . . . . . . . . . . . . 3 58 2.1. SSL Stripping . . . . . . . . . . . . . . . . . . . . . . . 3 59 2.2. STARTTLS Command Injection Attack (CVE-2011-0411) . . . . . 3 60 2.3. BEAST (CVE-2011-3389) . . . . . . . . . . . . . . . . . . . 4 61 2.4. Padding Oracle Attacks . . . . . . . . . . . . . . . . . . 4 62 2.5. Attacks on RC4 . . . . . . . . . . . . . . . . . . . . . . 4 63 2.6. Compression Attacks: CRIME, TIME and BREACH . . . . . . . . 5 64 2.7. Certificate and RSA-Related Attacks . . . . . . . . . . . . 5 65 2.8. Theft of RSA Private Keys . . . . . . . . . . . . . . . . . 6 66 2.9. Diffie-Hellman Parameters . . . . . . . . . . . . . . . . . 6 67 2.10. Renegotiation (CVE-2009-3555) . . . . . . . . . . . . . . . 6 68 2.11. Triple Handshake (CVE-2014-1295) . . . . . . . . . . . . . 6 69 2.12. Virtual Host Confusion . . . . . . . . . . . . . . . . . . 7 70 2.13. Denial of Service . . . . . . . . . . . . . . . . . . . . . 7 71 2.14. Implementation Issues . . . . . . . . . . . . . . . . . . . 7 72 2.15. Usability . . . . . . . . . . . . . . . . . . . . . . . . . 8 73 3. Applicability to DTLS . . . . . . . . . . . . . . . . . . . . 8 74 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 75 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 76 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 77 7. Informative References . . . . . . . . . . . . . . . . . . . 9 78 Appendix A. Appendix: Change Log . . . . . . . . . . . . . . . . 12 79 A.1. draft-ietf-uta-tls-attacks-05 . . . . . . . . . . . . . . . 13 80 A.2. draft-ietf-uta-tls-attacks-04 . . . . . . . . . . . . . . . 13 81 A.3. draft-ietf-uta-tls-attacks-03 . . . . . . . . . . . . . . . 13 82 A.4. draft-ietf-uta-tls-attacks-02 . . . . . . . . . . . . . . . 13 83 A.5. draft-ietf-uta-tls-attacks-01 . . . . . . . . . . . . . . . 13 84 A.6. draft-ietf-uta-tls-attacks-00 . . . . . . . . . . . . . . . 13 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 87 1. Introduction 89 Over the last few years there have been several major attacks on 90 Transport Layer Security (TLS) [RFC5246], including attacks on its 91 most commonly used ciphers and modes of operation. Details are given 92 in Section 2, but a quick summary is that both AES-CBC and RC4, which 93 together make up for most current usage, have been seriously attacked 94 in the context of TLS. 96 This situation was one of the motivations for the creation of the UTA 97 working group, which was tasked with the creation of generic and 98 protocol-specific recommendations for the use of TLS along with 99 Datagram TLS (DTLS) [RFC6347] (unless otherwise noted under 100 Section 3, all of the information provided in this document applies 101 to DTLS). 103 "Attacks always get better; they never get worse" (ironically, this 104 saying is attributed to the U.S. National Security Agency, the NSA). 105 This attacks summarized in this document reflect our knowledge as of 106 this writing. It seems likely that new attacks will be discovered in 107 the future. 109 For a more detailed discussion of the attacks listed here, the 110 interested reader is referred to [Attacks-iSec]. 112 2. Attacks on TLS 114 This section lists the attacks that motivated the current 115 recommendations in [I-D.ietf-uta-tls-bcp]. This list is not intended 116 to be an extensive survey of the security of TLS. 118 While there are widely deployed mitigations for some of the attacks 119 listed below, we believe that their root causes necessitate a more 120 systematic solution, which we have attempted to develop in 121 [I-D.ietf-uta-tls-bcp]. 123 When an identifier exists for an attack, we have included its CVE 124 (Common Vulnerabilities and Exposures) ID. CVE [CVE] is an 125 extensive, industry-wide database of software vulnerabilities. 127 2.1. SSL Stripping 129 Various attacks attempt to remove the use of SSL/TLS altogether, by 130 modifying unencrypted protocols that request the use of TLS, 131 specifically modifying HTTP traffic and HTML pages as they pass on 132 the wire. These attacks are known collectively as SSL Stripping (a 133 form of the more generic "downgrade attack") and were first 134 introduced by Moxie Marlinspike [SSL-Stripping]. In the context of 135 Web traffic, these attacks are only effective if the client initially 136 accesses a Web server using HTTP. A commonly used mitigation is HTTP 137 Strict Transport Security (HSTS) [RFC6797]. 139 2.2. STARTTLS Command Injection Attack (CVE-2011-0411) 141 Similarly, there are attacks on the transition between unprotected 142 and TLS-protected traffic. A number of IETF application protocols 143 have used an application-level command, usually STARTTLS, to upgrade 144 a clear-text connection to use TLS. Multiple implementations of 145 STARTTLS had a flaw where an application-layer input buffer retained 146 commands that were pipelined with the STARTTLS command, such that 147 commands received prior to TLS negotiation are executed after TLS 148 negotiation. This problem is resolved by requiring the application- 149 level command input buffer to be empty before negotiating TLS. Note 150 that this flaw lives in the application layer code and does not 151 impact the TLS protocol directly. 153 STARTLS and similar mechanisms are vulnerable to downgrade attacks 154 whereby the attacker simply removes the STARTTLS indication from the 155 (unprotected) request. This cannot be mitigated unless HSTS-like 156 solutions are added. 158 2.3. BEAST (CVE-2011-3389) 160 The BEAST attack [BEAST] uses issues with the TLS 1.0 implementation 161 of CBC (that is, the predictable initialization vector) to decrypt 162 parts of a packet, and specifically to decrypt HTTP cookies when HTTP 163 is run over TLS. 165 2.4. Padding Oracle Attacks 167 A consequence of the MAC-then-encrypt design in all current versions 168 of TLS is the existence of padding oracle attacks [Padding-Oracle]. 169 A recent incarnation of these attacks is the Lucky Thirteen attack 170 (CVE-2013-0169) [CBC-Attack], a timing side-channel attack that 171 allows the attacker to decrypt arbitrary ciphertext. 173 The Lucky Thirteen attack can be mitigated by using authenticated 174 encryption like AES-GCM [RFC5288] or encrypt-then-mac 175 [I-D.ietf-tls-encrypt-then-mac] instead of the TLS default of MAC- 176 then-encrypt. 178 An even newer variant of the padding oracle attack, one that does not 179 use timing information, is the POODLE attack (CVE-2014-3566) [POODLE] 180 on SSL 3.0. This attack has no known mitigation. 182 2.5. Attacks on RC4 184 The RC4 algorithm [RC4] has been used with TLS (and previously, SSL) 185 for many years. RC4 has long been known to have a variety of 186 cryptographic weaknesses, e.g. [RC4-Attack-Pau], [RC4-Attack-Man], 187 [RC4-Attack-FMS]. Recent cryptanalysis results [RC4-Attack-AlF] 188 exploit biases in the RC4 keystream to recover repeatedly encrypted 189 plaintexts. 191 These recent results are on the verge of becoming practically 192 exploitable; currently they require 2^26 sessions or 13x2^30 193 encryptions. As a result, RC4 can no longer be seen as providing a 194 sufficient level of security for TLS sessions. For further details, 195 the reader is referred to [I-D.ietf-tls-prohibiting-rc4] and the 196 references it cites. 198 2.6. Compression Attacks: CRIME, TIME and BREACH 200 The CRIME attack [CRIME] (CVE-2012-4929) allows an active attacker to 201 decrypt ciphertext (specifically, cookies) when TLS is used with TLS 202 level compression. 204 The TIME attack [TIME] and the later BREACH attack [BREACH] (CVE- 205 2013-3587, though the number has not been officially allocated) both 206 make similar use of HTTP-level compression to decrypt secret data 207 passed in the HTTP response. We note that compression of the HTTP 208 message body is much more prevalent than compression at the TLS 209 level. 211 The former attack can be mitigated by disabling TLS compression. We 212 are not aware of mitigations at the TLS protocol level to the latter 213 attack, and so application-level mitigations are needed (see 214 [BREACH]). For example, implementations of HTTP that use CSRF tokens 215 will need to randomize them. Even the best practices and 216 recommendations from [I-D.ietf-uta-tls-bcp] are insufficient to 217 thwart this attack. 219 2.7. Certificate and RSA-Related Attacks 221 There have been several practical attacks on TLS when used with RSA 222 certificates (the most common use case). These include 223 [Bleichenbacher98] and [Klima03]. While the Bleichenbacher attack 224 has been mitigated in TLS 1.0, the Klima attack relies on a version- 225 check oracle is only mitigated by TLS 1.1. 227 The use of RSA certificates often involves exploitable timing issues 228 [Brumley03] (CVE-2003-0147), unless the implementation takes care to 229 explicitly eliminate them. 231 A recent certificate fuzzing tool [Brubaker2014using] uncovered 232 numerous vulnerabilities in different TLS libraries, related to 233 certificate validation. 235 2.8. Theft of RSA Private Keys 237 When TLS is used with most non-Diffie Hellman cipher suites, it is 238 sufficient to obtain the server's private key in order to decrypt any 239 sessions (past and future) that were initiated with that server. 240 This technique is used, for example, by the popular Wireshark network 241 sniffer to inspect TLS-protected connections. 243 It is known that stolen (or otherwise obtained) private keys have 244 been used as part of large-scale monitoring [RFC7258] of certain 245 servers. 247 Such attacks can be mitigated by better protecting the private key, 248 e.g. using OS protections or dedicated hardware. Even more effective 249 is the use of cipher suites that offer "forward secrecy", the 250 property that revealing a secret such as a private key does not 251 expose past or future sessions to a passive attacker. 253 2.9. Diffie-Hellman Parameters 255 TLS allows the definition of ephemeral Diffie-Hellman and Elliptic 256 Curve Diffie-Hellman parameters in its respective key exchange modes. 257 This results in an attack detailed in [Cross-Protocol]. Using 258 predefined DH groups, as proposed in 259 [I-D.ietf-tls-negotiated-ff-dhe], would mitigate this attack. 261 In addition, clients that do not properly verify the received 262 parameters are exposed to man in the middle (MITM) attacks. 263 Unfortunately the TLS protocol does not mandate this verification 264 (see [RFC6989] for analogous information for IPsec). 266 2.10. Renegotiation (CVE-2009-3555) 268 A major attack on the TLS renegotiation mechanism applies to all 269 current versions of the protocol. The attack and the TLS extension 270 that resolves it are described in [RFC5746]. 272 2.11. Triple Handshake (CVE-2014-1295) 274 The triple handshake attack [BhargavanDFPS14] enables the attacker to 275 cause two TLS connections to share keying material. This leads to a 276 multitude of attacks, e.g. Man-in-the-Middle, breaking safe 277 renegotiation, and breaking channel binding via TLS Exporter 278 [RFC5705] or "tls-unique" [RFC5929]. 280 2.12. Virtual Host Confusion 282 A recent article [Delignat14] describes a security issue whereby 283 SSLv3 fallback and improper handling of session caches on the server 284 side can be abused by an attacker to establish a malicious connection 285 to a virtual host other than the one originally intended and approved 286 by the server. This attack is especially serious in performance 287 critical environments where sharing of SSLv3 session caches is very 288 common. 290 2.13. Denial of Service 292 Server CPU power has progressed over the years so that TLS can now be 293 turned on by default. However, the risk of malicious clients and 294 coordinated groups of clients ("botnets") mounting denial of service 295 attacks is still very real. TLS adds another vector for 296 computational attacks, since a client can easily (with little 297 computational effort) force the server to expend relatively large 298 computational work. It is known that such attacks have in fact been 299 mounted. 301 2.14. Implementation Issues 303 Even when the protocol is properly specified, this does not guarantee 304 the security of implementations. In fact there are very common 305 issues that often plague TLS implementations. In particular, when 306 integrating into higher-level protocols, TLS and its PKI-based 307 authentication are sometimes the source of misunderstandings and 308 implementation "shortcuts". An extensive survey of these issues can 309 be found in [Georgiev2012]. 311 o Implementations might omit validation of the server certificate 312 altogether. For example, this is true of the default 313 implementation of HTTP client libraries in Python 2 (see e.g. 314 CVE-2013-2191). 316 o Implementations might not validate the server identity. This 317 validation typically amounts to matching the protocol-level server 318 name with the certificate's Subject Alternative Name field. Note: 319 this same information is often also found in the Common Name part 320 of the Distinguished Name, and some validators incorrectly 321 retrieve it from there instead of from the Subject Alternative 322 Name. 324 o Implementations might validate the certificate chain incorrectly 325 or not at all, or use an incorrect or outdated trust anchor list. 327 An implementation attack of a different kind, one that exploits a 328 simple coding mistake (bounds check), is the Heartbleed attack (CVE- 329 2014-0160) that affected a wide swath of the Internet when it was 330 discovered in April 2014. 332 2.15. Usability 334 Many TLS endpoints, such as browsers and mail clients, allow the user 335 to explicitly accept an invalid server certificate. This often takes 336 the form of a UI dialog (e.g., "do you accept this server?") and 337 users have been conditioned to respond in the affirmative in order to 338 allow the connection to take place. 340 This user behavior is used by (arguably legitimate) "SSL proxies" 341 that decrypt and re-encrypt the TLS connection in order to enforce 342 local security policy. It is also abused by attackers whose goal is 343 to gain access to the encrypted information. 345 Mitigation is complex and will probably involve a combination of 346 protocol mechanisms (HSTS, certificate pinning 347 [I-D.ietf-websec-key-pinning]) and very careful UI design. 349 3. Applicability to DTLS 351 DTLS [RFC4347] [RFC6347] is an adaptation of TLS for UDP. 353 With respect to the attacks described in the current document, DTLS 354 1.0 is equivalent to TLS 1.1. The only exception is RC4, which is 355 disallowed in DTLS. DTLS 1.2 is equivalent to TLS 1.2. 357 4. IANA Considerations 359 This document requires no IANA actions. [Note to RFC Editor: please 360 remove this whole section before publication.] 362 5. Security Considerations 364 This document describes protocol attacks in an informational manner, 365 and in itself does not have any security implications. Its companion 366 documents, especially [I-D.ietf-uta-tls-bcp], certainly do. 368 6. Acknowledgments 370 We would like to thank Stephen Farrell, Simon Josefsson, John 371 Mattsson, Yoav Nir, Kenny Paterson, Patrick Pelletier, Tom Ritter, 372 Rich Salz and Meral Shirazipour for their feedback on this document. 373 We thank Andrei Popov for contributing text on RC4, Kohei Kasamatsu 374 for text on Lucky13, Ilari Liusvaara for text on attacks and on DTLS, 375 Aaron Zauner for text on virtual host confusion, and Chris Newman for 376 text on STARTTLS command injection. 378 During IESG review, Richard Barnes, Barry Leiba, and Kathleen 379 Moriarty caught several issues that needed to be addressed. 381 The authors gratefully acknowledge the assistance of Leif Johansson 382 and Orit Levin as the working group chairs and Pete Resnick as the 383 sponsoring Area Director. 385 The document was prepared using the lyx2rfc tool, created by Nico 386 Williams. 388 7. Informative References 390 [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 391 Security", RFC 4347, April 2006. 393 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 394 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 396 [RFC5288] Salowey, J., Choudhury, A., and D. McGrew, "AES Galois 397 Counter Mode (GCM) Cipher Suites for TLS", RFC 5288, 398 August 2008. 400 [RFC5705] Rescorla, E., "Keying Material Exporters for Transport 401 Layer Security (TLS)", RFC 5705, March 2010. 403 [RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov, 404 "Transport Layer Security (TLS) Renegotiation Indication 405 Extension", RFC 5746, February 2010. 407 [RFC5929] Altman, J., Williams, N., and L. Zhu, "Channel Bindings 408 for TLS", RFC 5929, July 2010. 410 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 411 Security Version 1.2", RFC 6347, January 2012. 413 [RFC6797] Hodges, J., Jackson, C., and A. Barth, "HTTP Strict 414 Transport Security (HSTS)", RFC 6797, November 2012. 416 [RFC6989] Sheffer, Y. and S. Fluhrer, "Additional Diffie-Hellman 417 Tests for the Internet Key Exchange Protocol Version 2 418 (IKEv2)", RFC 6989, July 2013. 420 [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an 421 Attack", BCP 188, RFC 7258, May 2014. 423 [I-D.ietf-uta-tls-bcp] 424 Sheffer, Y., Holz, R., and P. Saint-Andre, 425 "Recommendations for Secure Use of TLS and DTLS", draft- 426 ietf-uta-tls-bcp-05 (work in progress), October 2014. 428 [I-D.ietf-tls-prohibiting-rc4] 429 Popov, A., "Prohibiting RC4 Cipher Suites", draft-ietf- 430 tls-prohibiting-rc4-00 (work in progress), July 2014. 432 [I-D.ietf-tls-encrypt-then-mac] 433 Gutmann, P., "Encrypt-then-MAC for TLS and DTLS", draft- 434 ietf-tls-encrypt-then-mac-03 (work in progress), July 435 2014. 437 [I-D.ietf-tls-negotiated-ff-dhe] 438 Gillmor, D., "Negotiated Finite Field Diffie-Hellman 439 Ephemeral Parameters for TLS", draft-ietf-tls-negotiated- 440 ff-dhe-02 (work in progress), October 2014. 442 [I-D.ietf-websec-key-pinning] 443 Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning 444 Extension for HTTP", draft-ietf-websec-key-pinning-21 445 (work in progress), October 2014. 447 [CVE] MITRE, , "Common Vulnerabilities and Exposures", 448 . 450 [CBC-Attack] 451 AlFardan, N. and K. Paterson, "Lucky Thirteen: Breaking 452 the TLS and DTLS Record Protocols", IEEE Symposium on 453 Security and Privacy , 2013. 455 [BEAST] Rizzo, J. and T. Duong, "Browser Exploit Against SSL/TLS", 456 2011, . 459 [POODLE] Moeller, B., Duong, T., and K. Kotowicz, "This POODLE 460 Bites:Exploiting the SSL 3.0 Fallback", 2014, 461 . 463 [CRIME] Rizzo, J. and T. Duong, "The CRIME Attack", EKOparty 464 Security Conference 2012, 2012. 466 [BREACH] Prado, A., Harris, N., and Y. Gluck, "The BREACH Attack", 467 2013, . 469 [TIME] Be'ery, T. and A. Shulman, "A Perfect CRIME? Only TIME 470 Will Tell", Black Hat Europe 2013, 2013, 471 . 474 [RC4] Schneier, B., "Applied Cryptography: Protocols, 475 Algorithms, and Source Code in C, 2nd Ed.", 1996. 477 [RC4-Attack-FMS] 478 Fluhrer, S., Mantin, I., and A. Shamir, "Weaknesses in the 479 Key Scheduling Algorithm of RC4", Selected Areas in 480 Cryptography , 2001. 482 [RC4-Attack-AlF] 483 AlFardan, N., Bernstein, D., Paterson, K., Poettering, B., 484 and J. Schuldt, "On the Security of RC4 in TLS", Usenix 485 Security Symposium 2013, 2013, 486 . 489 [Georgiev2012] 490 Georgiev, M., Iyengar, S., Jana, S., Anubhai, R., Boneh, 491 D., and V. Shmatikov, "The most dangerous code in the 492 world: validating SSL certificates in non-browser 493 software", 2012, 494 . 496 [Attacks-iSec] 497 Sarkar, P. and S. Fitzgerald, "Attacks on SSL, a 498 comprehensive study of BEAST, CRIME, TIME, BREACH, Lucky13 499 and RC4 biases", 8 2013, 500 . 503 [Padding-Oracle] 504 Vaudenay, S., "Security Flaws Induced by CBC Padding 505 Applications to SSL, IPSEC, WTLS...", EUROCRYPT 2002, 506 2002, . 509 [Cross-Protocol] 510 Mavrogiannopoulos, N., Vercauteren, F., Velichkov, V., and 511 B. Preneel, "A cross-protocol attack on the TLS protocol", 512 2012, . 514 [RC4-Attack-Pau] 515 Paul, G. and S. Maitra, "Permutation after RC4 key 516 scheduling reveals the secret key.", 2007, 517 . 520 [RC4-Attack-Man] 521 Mantin, I. and A. Shamir, "A practical attack on broadcast 522 RC4", 2001. 524 [SSL-Stripping] 525 Marlinspike, M., "SSL Stripping", February 2009, 526 . 528 [Bleichenbacher98] 529 Bleichenbacher, D., "Chosen ciphertext attacks against 530 protocols based on the RSA encryption standard pkcs1", 531 1998. 533 [Klima03] Klima, V., Pokorny, O., and T. Rosa, "Attacking RSA-based 534 sessions in SSL/TLS", 2003. 536 [Brumley03] 537 Brumley, D. and D. Boneh, "Remote timing attacks are 538 practical", 2003. 540 [Brubaker2014using] 541 Brubaker, C., Jana, S., Ray, B., Khurshid, S., and V. 542 Shmatikov, "Using frankencerts for automated adversarial 543 testing of certificate validation in SSL/TLS 544 implementations", 2014. 546 [Delignat14] 547 Delignat-Lavaud, A. and K. Bhargavan, "Virtual Host 548 Confusion: Weaknesses and Exploits", Black Hat 2014, 2014. 550 [BhargavanDFPS14] 551 Bhargavan, K., Delignat-Lavaud, A., Fournet, C., Pironti, 552 A., and P. Strub, "Triple handshakes and cookie cutters: 553 breaking and fixing authentication over tls", 2014, 554 . 557 Appendix A. Appendix: Change Log 559 Note to RFC Editor: please remove this section before publication. 561 A.1. draft-ietf-uta-tls-attacks-05 563 o Implemented Gen-ART and IESG reviews. 565 A.2. draft-ietf-uta-tls-attacks-04 567 o Implemented AD review comments. 569 A.3. draft-ietf-uta-tls-attacks-03 571 o Implemented WG Last Call comments. 573 o Virtual host confusion. 575 o STARTTLS command injection. 577 o Added CVE numbers. 579 A.4. draft-ietf-uta-tls-attacks-02 581 o Added implementation issues ("most dangerous code"), 582 renegotiation, triple handshake. 584 o Added text re: mitigation of Lucky13. 586 o Added applicability to DTLS. 588 A.5. draft-ietf-uta-tls-attacks-01 590 o Added SSL Stripping, attacks related to certificates, Diffie 591 Hellman parameters and denial of service. 593 o Expanded on RC4 attacks, thanks to Andrei Popov. 595 A.6. draft-ietf-uta-tls-attacks-00 597 o Initial version, extracted from draft-sheffer-tls-bcp-01. 599 Authors' Addresses 601 Yaron Sheffer 602 Porticor 603 29 HaHarash St. 604 Hod HaSharon 4501303 605 Israel 607 Email: yaronf.ietf@gmail.com 608 Ralph Holz 609 Technische Universitaet Muenchen 610 Boltzmannstr. 3 611 Garching 85748 612 Germany 614 Email: holz@net.in.tum.de 616 Peter Saint-Andre 617 &yet 619 Email: peter@andyet.com 620 URI: https://andyet.com/