Posted on 06/30/2015 8:21:27 PM PDT by zeugma
A post for the computer techies on the site
Internet Engineering Task Force (IETF) R. Barnes
Request for Comments: 7568 M. Thomson
Updates: 5246 Mozilla
Category: Standards Track A. Pironti
ISSN: 2070-1721 INRIA
A. Langley
Google
June 2015
Abstract
The Secure Sockets Layer version 3.0 (SSLv3), as specified in RFC 6101, is not sufficiently secure. This document requires that SSLv3 not be used. The replacement versions, in particular, Transport Layer Security (TLS) 1.2 (RFC 5246), are considerably more secure and capable protocols.
This document updates the backward compatibility section of RFC 5246 and its predecessors to prohibit fallback to SSLv3.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7568.
Copyright Notice
Copyright (c) 2015 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 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction
2. Terminology
3. Do Not Use SSL Version 3.0
4. SSLv3 Is Comprehensively Broken
4.1. Record Layer
4.2. Key Exchange
4.3. Custom Cryptographic Primitives
5. Limited Capabilities
6. Security Considerations
7. References
7.1. Normative References>
7.2. Informative References
Authors' Addresses
Since it was released in 1996, the SSLv3 protocol [RFC6101] has been subject to a long series of attacks, both on its key exchange mechanism and on the encryption schemes it supports. Despite being replaced by TLS 1.0 [RFC2246] in 1999, and subsequently TLS 1.1 in 2002 [RFC4346] and 1.2 in 2006 [RFC5246], availability of these replacement versions has not been universal. As a result, many implementations of TLS have permitted the negotiation of SSLv3.
The predecessor of SSLv3, SSL version 2, is no longer considered sufficiently secure [RFC6176]. SSLv3 now follows.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
SSLv3 MUST NOT be used. Negotiation of SSLv3 from any version of TLS MUST NOT be permitted.
Any version of TLS is more secure than SSLv3, though the highest version available is preferable.
Pragmatically, clients MUST NOT send a ClientHello with ClientHello.client_version set to {03,00}. Similarly, servers MUST NOT send a ServerHello with ServerHello.server_version set to {03,00}. Any party receiving a Hello message with the protocol version set to {03,00} MUST respond with a "protocol_version" alert message and close the connection.
Historically, TLS specifications were not clear on what the record layer version number (TLSPlaintext.version) could contain when sending ClientHello. Appendix E of [RFC5246] notes that TLSPlaintext.version could be selected to maximize interoperability, though no definitive value is identified as ideal. That guidance is still applicable; therefore, TLS servers MUST accept any value {03,XX} (including {03,00}) as the record layer version number for ClientHello, but they MUST NOT negotiate SSLv3.
The non-deterministic padding used in the Cipher Block Chaining (CBC) construction of SSLv3 trivially permits the recovery of plaintext [POODLE]. More generally, the CBC modes of SSLv3 use a flawed MAC- then-encrypt construction that has subsequently been replaced in TLS versions [RFC7366]. Unfortunately, the mechanism to correct this flaw relies on extensions: a feature added in TLS 1.0. SSLv3 cannot be updated to correct this flaw in the same way.
The flaws in the CBC modes in SSLv3 are mirrored by the weakness of the stream ciphers it defines. Of those defined, only RC4 is currently in widespread use. RC4, however, exhibits serious biases and is also no longer fit for use [RFC7465].
This leaves SSLv3 with no suitable record protection mechanism.
The SSLv3 key exchange is vulnerable to man-in-the-middle attacks when renegotiation [RFC5746] or session resumption [TRIPLE-HS] are used. Each flaw has been fixed in TLS by means of extensions. Again, SSLv3 cannot be updated to correct these flaws.
SSLv3 defines custom constructions for Pseudorandom Function (PRF), Hashed Message Authentication Code (HMAC), and digital signature primitives. Such constructions lack the deep cryptographic scrutiny that standard constructions used by TLS have received. Furthermore, all SSLv3 primitives rely on SHA-1 [RFC3174] and MD5 [RFC1321]: these hash algorithms are considered weak and are being systematically replaced with stronger hash functions, such as SHA-256 [FIPS180-4].
SSLv3 is unable to take advantage of the many features that have been added to recent TLS versions. This includes the features that are enabled by ClientHello extensions, which SSLv3 does not support.
Though SSLv3 can benefit from new cipher suites, it cannot benefit from new cryptographic modes and features. Of these, the following are particularly prominent:
Authenticated Encryption with Additional Data (AEAD) modes are added in [RFC5246].
Elliptic Curve Diffie-Hellman (ECDH) and Digital Signature Algorithm (ECDSA) are added in [RFC4492].
Stateless session tickets [RFC5077].
A datagram mode of operation, DTLS [RFC6347].
Application-layer protocol negotiation [RFC7301].
This entire document aims to improve security by prohibiting the use of a protocol that is not secure.
[RFC2119] Bradner, S., "Key words for use in RFCs to IndicateRequirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, DOI 10.17487/RFC2246, January 1999, <http://www.rfc-editor.org/info/rfc2246>.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.1", RFC 4346, DOI 10.17487/RFC4346, April 2006, <http://www.rfc-editor.org/info/rfc4346>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, <http://www.rfc-editor.org/info/rfc5246>.
[RFC6101] Freier, A., Karlton, P., and P. Kocher, "The Secure Sockets Layer (SSL) Protocol Version 3.0", RFC 6101, DOI 10.17487/RFC6101, August 2011, <http://www.rfc-editor.org/info/rfc6101>.
[RFC7366] Gutmann, P., "Encrypt-then-MAC for Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", RFC 7366, DOI 10.17487/RFC7366, September 2014, <http://www.rfc-editor.org/info/rfc7366>.
[RFC7465] Popov, A., "Prohibiting RC4 Cipher Suites", RFC 7465, DOI 10.17487/RFC7465, February 2015, <http://www.rfc-editor.org/info/rfc7465>.
[FIPS180-4] U.S. National Institute of Standards and Technology, "Secure Hash Standard", FIPS 180-4, March 2012.
[POODLE] Moeller, B., "This POODLE bites: exploiting the SSL 3.0 fallback", October 2014, <http://googleonlinesecurity.blogspot.com/2014/10/ this-poodle-bites-exploiting-ssl-30.html>.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, DOI 10.17487/RFC1321, April 1992, <http://www.rfc-editor.org/info/rfc1321>.
[RFC3174] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1 (SHA1)", RFC 3174, DOI 10.17487/RFC3174, September 2001, <http://www.rfc-editor.org/info/rfc3174>.
[RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B. Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS)", RFC 4492, DOI 10.17487/RFC4492, May 2006, <http://www.rfc-editor.org/info/rfc4492>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig, "Transport Layer Security (TLS) Session Resumption without Server-Side State", RFC 5077, DOI 10.17487/RFC5077, January 2008, <http://www.rfc-editor.org/info/rfc5077>.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov, "Transport Layer Security (TLS) Renegotiation Indication Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010, <http://www.rfc-editor.org/info/rfc5746>.
[RFC6176] Turner, S. and T. Polk, "Prohibiting Secure Sockets Layer (SSL) Version 2.0", RFC 6176, DOI 10.17487/RFC6176, March 2011, <http://www.rfc-editor.org/info/rfc6176>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, "Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, July 2014, <http://www.rfc-editor.org/info/rfc7301>.
[TRIPLE-HS] Bhargavan, K., Delignat-Lavaud, A., Fournet, C., Pironti, A., and P-Y. Strub, "Triple Handshakes and Cookie Cutters: Breaking and Fixing Authentication over TLS", IEEE Symposium on Security and Privacy, 2014.
Authors' Addresses
Richard Barnes Mozilla
EMail: rlb@ipv.sx
Martin Thomson Mozilla
EMail: martin.thomson@gmail.com
Alfredo Pironti INRIA
EMail: alfredo@pironti.eu
Adam Langley Google
EMail: agl@google.com
Indeed. I'd say the work necessary to implement this far exceeds that of creating a 7-page RFC.!
My favorite RFC is still #1149 "A Standard for the Transmission of IP Datagrams on Avian Carriers"
Are you sure they are using SSL? Just because it's https does't necessarily mean it's SSL. Could be TLS. The only way I know to check is to use the openssl command so you can actually see what it's doing.
You may want to see
Upcoming changes to Windows 10 Insider Preview builds [UPDATED 6/22]: http://blogs.windows.com/bloggingwindows/2015/06/19/upcoming-changes-to-windows-10-insider-preview-builds/
If an Insider could install the W/10 for free even without having W/8 or 8 then it seems that they could continue to run a valid install of the latter OS as well.
Meanwhile, note that adjusting date and time on Build 10130 requires more hoops than before. Instead,, just run
control.exe /name Microsoft.DateAndTime
Other Canonical names: https://msdn.microsoft.com/en-us/library/windows/desktop/ee330741%28v=vs.85%29.aspx
You mean the Poles did it.But the British did it.
The Poles did a lot. But even with what they got from the Poles, the British had a continuous, devilishly-difficult task on their plate. So hard that I sincerely believed it to be impossible when I first thought of it. Turns, out, the Germans thought so too - and were defeated because the British did what I would have claimed wasn’t possible.
SSL 3.0 was prohibited for PCI compliance a while ago. TLS 1.0 was prohibited in April 2015.
The latter is more problematic because it prevents interoperability with older browsers and devices like Android 4.3 and IE10. It also messes up RDS and MSSQL because both default to TLS 1.0 and are not easy to change.
Actually, the CA has no control over the exportability of a cert with a private key. The 'no-export' flag is trivially circumventable and is basically no protection at all. There are dozens of cracker tools that can scoop private keys out of compromised machines. If Apache/IIS or other non-TCB apps can use the key then a hacker on a compromised machine can use it too.
Man-in-the-middle has nothing to do with it. That's an entirely different method of attack.
Keep in mind that I’m speaking from a Microsoft certificate services background. If you have the cert marked to disallow export, you can’t export it. There’s no reliable mechanism to get the private key off of the machine without involving the CA, in which case, you have admin rights in the certificate environment anyway and are more privileged than the users using the cert.
The CA has nothing to do with PK exportability. The cert you submit to VeriSign is simply the X.509 public fields, either base64 or bibary BER encoded. That’s it. The private key info and all related settings like the non-export flag are kept within the DPA and never leave the Windows box.
How do I know this? Because I wrote a commercial app that exports the cert private keys (among other things) for Windows Server disaster recovery (U-Move).
The bottom line is that if a hacker gains control of the server they also own all the data on it. They can then inject a DLL into the Local Security Authority and grab whatever they want. No flag is going to save you.
I wasn’t insinuating that the no-export flag is going to save anyone from anything. It’s a roadblock, not a brick wall. However, having it is a lot better than not since idiot users or app owners could inadvertently expose a system moreso than if the cert was left alone.
In a fully-integrated ADCS environment, you can't generate a cert without specifying a cert template. If the cert template selected during manual cert generation (i.e. through X.509 input) has the no-export flag configured, the cert generated cannot be exported on a Windows-enabled system (using Windows-based tools).
I'm not talking about someone with the know-how and wherewithal to circumvent system protections, I'm talking about users in a corporate AD environment.
Also see, We'd like your survey feedback - official or scam ?
Just got this email myself, and as one said," I started answering the survey, but when it started to get into asking more personal questions that had nothing to do with Windows 10 I quit and didn't finish as it wouldn't let you skip questions."
But so far MS has not required us to explicitly affirm we will not use its OS that "in a way that threatens...defames...degrades...or intimidates an individual or group of individuals for any reason; including on the basis of ...sexual orientation...or religion; or incites or encourages anyone else to do so."
"...promotes...the purchase and sale of ammunition or firearms."
Which "Prohibited Uses" applies to "all MSN and Windows Live and other services that allow users to post or share content with others, when those services display or link to this Code of Conduct (the 'services')." - http://windows.microsoft.com/en-us/windows-live/code-of-conduct
Sounds like FR is excluded. But since an OS itself allows users to post or share content with others, what is to stop them from applying this to the use of its OS?
This applies to OneDrive, but try to stop that from even running. Deprecating Secure Sockets Layer Version is one thing, but it is another to prohibit using MS software that in a way that deprecates a group of individuals for any reason, including on the basis of sexual orientation or religion; or incites or encourages anyone else to do so.
I want to use a piece of software that enables me to view Linux in Windows (which MS should enable), but which the use of the software together with material that displays prejudice based on religion...or sexual orientation is strictly prohibited. - http://www.diskinternals.com/download/zd1435765016144/Linux_Reader.exe
So much for free software as in free for anyone to use. Their loss.
Today, an encryption mechanism is considered broken if a way can be found to deduce the key given a *known* encrypted text; a given test message that is already known by the attacker.
In other words, “The attacker is able to have any text he likes encrypted with the unknown key. The task is to determine the key used for encryption.”
This would typically mean finding a statistical or mathematical way to simplify an attack. (See also rainbow hash tables.)
http://math.colorado.edu/~hiba/crypto/cryptanalysis.html
Sometimes it’s not the algorithm itself that’s at fault, but rather the implementation details:
More information here: https://owasp.org/index.php/Main_Page
ok thx it is https but it could be tsl thx for responding
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