Issue #9424 has been updated by Usaku NAKAMURA.

Status changed from Feedback to Closed

Applied in changeset ruby-200:r48110.

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merge revision(s) 45274,45278,45280,48097: [Backport #9424]

	* lib/openssl/ssl.rb: Explicitly whitelist the default
	  SSL/TLS ciphers. Forbid SSLv2 and SSLv3, disable
	  compression by default.
	  Reported by Jeff Hodges.
	  [ruby-core:59829] [Bug #9424]

	* test/openssl/test_ssl.rb: Reuse TLS default options from
	  OpenSSL::SSL::SSLContext::DEFAULT_PARAMS.

	* ext/openssl/lib/openssl/ssl.rb (DEFAULT_PARAMS): override
	  options even if OpenSSL::SSL::OP_NO_SSLv3 is not defined.
	  this is pointed out by Stephen Touset. [ruby-core:65711] [Bug #9424]

----------------------------------------
Bug #9424: ruby 1.9 & 2.x has insecure SSL/TLS client defaults 
https://bugs.ruby-lang.org/issues/9424#change-49605

* Author: Jeff Hodges
* Status: Closed
* Priority: Normal
* Assignee: Tomoyuki Chikanaga
* Category: ext/openssl
* Target version: current: 2.2.0
* ruby -v: -
* Backport: 1.9.3: WONTFIX, 2.0.0: REQUIRED, 2.1: DONE
----------------------------------------
Ruby 1.9, 2.0, and 2.1 use insecure defaults for SSL/TLS client connections. They have inherited or overridden configs that make the OpenSSL-controlled connections insecure. Note: both OpenSSL's and Ruby's defaults in all tested versions are currently insecure. Confirmation of the issues with Ruby's TLS client can be done with the code in [1].

Ruby is using TLS compression by default. This opens Ruby clients to the CRIME attack[2].

Ruby also uses a variety of insecure cipher suites. These cipher suites either use key sizes much smaller than the currently recommended size, making brute forcing a decryption easy, or do not check the veracity of the server's certificate making them susceptible to man-in-the-middle attacks[3][4].

Ruby also appears to allow SSLv2 connections by default. It does so by first trying to connect with a SSLv2 client hello with a higher SSL/TLS version inside of it which allows SSLv2 servers to work. SSLv2 was broken in the 1990s and is considered unsafe.

These issues expose Ruby users to attacks that have been known for many years, and are trivial to discover. These defaults are often build specific, and are not the same across platforms, but are consistently poor (the code in [1] can evaluate the build). A patch from a core developer on the security@ list is attached. However, the patch does not correct the suspect SSLv2 configuration. It is believed that Ruby 1.8 is also a concern, but, since it was obsoleted, it's not been investigated.

A report similar to this was sent to security / ruby-lang.org four days ago. The Ruby core developers have been unable to patch these problems in a timely manner for it for what I and others believe are concerning reasons. This ticket is being made to allow engineers outside of the small group that are on security@ to protect themselves from these attacks.

[1] https://gist.github.com/cscotta/8302049
[2] https://www.howsmyssl.com/s/about.html#tls-compression
[3] https://www.howsmyssl.com/s/about.html#insecure-cipher-suites
[4] TLS_DHE_DSS_WITH_DES_CBC_SHA - small keys
TLS_DHE_RSA_WITH_DES_CBC_SHA - small keys
TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA - MITM
TLS_ECDH_anon_WITH_AES_128_CBC_SHA - MITM
TLS_ECDH_anon_WITH_AES_256_CBC_SHA - MITM
TLS_ECDH_anon_WITH_RC4_128_SHA - MITM
TLS_RSA_WITH_DES_CBC_SHA - small keys
TLS_SRP_SHA_WITH_3DES_EDE_CBC_SHA - MITM
TLS_SRP_SHA_WITH_AES_128_CBC_SHA - MITM
TLS_SRP_SHA_WITH_AES_256_CBC_SHA - MITM

---Files--------------------------------
ruby_ssl.patch (1.08 KB)
change_ssl_defaults.diff (1.24 KB)
change_ssl_defaults.2.diff (2.13 KB)


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