From 56f1acf5ef8a432992497a04792ff4b3b2c6f286 Mon Sep 17 00:00:00 2001 From: Viktor Dukhovni Date: Wed, 17 Feb 2016 21:37:15 -0500 Subject: [PATCH] Disable SSLv2 default build, default negotiation and weak ciphers. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit SSLv2 is by default disabled at build-time. Builds that are not configured with "enable-ssl2" will not support SSLv2. Even if "enable-ssl2" is used, users who want to negotiate SSLv2 via the version-flexible SSLv23_method() will need to explicitly call either of: SSL_CTX_clear_options(ctx, SSL_OP_NO_SSLv2); or SSL_clear_options(ssl, SSL_OP_NO_SSLv2); as appropriate. Even if either of those is used, or the application explicitly uses the version-specific SSLv2_method() or its client or server variants, SSLv2 ciphers vulnerable to exhaustive search key recovery have been removed. Specifically, the SSLv2 40-bit EXPORT ciphers, and SSLv2 56-bit DES are no longer available. Mitigation for CVE-2016-0800 Reviewed-by: Emilia Käsper --- CHANGES | 17 +++++++++++++++++ Configure | 3 ++- NEWS | 2 +- ssl/s2_lib.c | 6 ++++++ ssl/ssl_lib.c | 7 +++++++ 5 files changed, 33 insertions(+), 2 deletions(-) diff --git a/CHANGES b/CHANGES index b95a3ed33f..f209b3e0d3 100644 --- a/CHANGES +++ b/CHANGES @@ -4,6 +4,23 @@ Changes between 1.0.1r and 1.0.1s [xx XXX xxxx] + * Disable SSLv2 default build, default negotiation and weak ciphers. SSLv2 + is by default disabled at build-time. Builds that are not configured with + "enable-ssl2" will not support SSLv2. Even if "enable-ssl2" is used, + users who want to negotiate SSLv2 via the version-flexible SSLv23_method() + will need to explicitly call either of: + + SSL_CTX_clear_options(ctx, SSL_OP_NO_SSLv2); + or + SSL_clear_options(ssl, SSL_OP_NO_SSLv2); + + as appropriate. Even if either of those is used, or the application + explicitly uses the version-specific SSLv2_method() or its client and + server variants, SSLv2 ciphers vulnerable to exhaustive search key + recovery have been removed. Specifically, the SSLv2 40-bit EXPORT + ciphers, and SSLv2 56-bit DES are no longer available. + [Viktor Dukhovni] + *) Disable SRP fake user seed to address a server memory leak. Add a new method SRP_VBASE_get1_by_user that handles the seed properly. diff --git a/Configure b/Configure index 0a5ffac750..ea74c91537 100755 --- a/Configure +++ b/Configure @@ -724,8 +724,9 @@ my %disabled = ( # "what" => "comment" [or special keyword "experimental "md2" => "default", "rc5" => "default", "rfc3779" => "default", - "sctp" => "default", + "sctp" => "default", "shared" => "default", + "ssl2" => "default", "store" => "experimental", "unit-test" => "default", "zlib" => "default", diff --git a/NEWS b/NEWS index 43405541d4..ce256aeb6a 100644 --- a/NEWS +++ b/NEWS @@ -7,7 +7,7 @@ Major changes between OpenSSL 1.0.1r and OpenSSL 1.0.1s [under development] - o + o Disable SSLv2 default build, default negotiation and weak ciphers. Major changes between OpenSSL 1.0.1q and OpenSSL 1.0.1r [28 Jan 2016] diff --git a/ssl/s2_lib.c b/ssl/s2_lib.c index 7e3674a685..82c1731549 100644 --- a/ssl/s2_lib.c +++ b/ssl/s2_lib.c @@ -156,6 +156,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { 128, }, +# if 0 /* RC4_128_EXPORT40_WITH_MD5 */ { 1, @@ -171,6 +172,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { 40, 128, }, +# endif /* RC2_128_CBC_WITH_MD5 */ { @@ -188,6 +190,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { 128, }, +# if 0 /* RC2_128_CBC_EXPORT40_WITH_MD5 */ { 1, @@ -203,6 +206,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { 40, 128, }, +# endif # ifndef OPENSSL_NO_IDEA /* IDEA_128_CBC_WITH_MD5 */ @@ -222,6 +226,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { }, # endif +# if 0 /* DES_64_CBC_WITH_MD5 */ { 1, @@ -237,6 +242,7 @@ OPENSSL_GLOBAL const SSL_CIPHER ssl2_ciphers[] = { 56, 56, }, +# endif /* DES_192_EDE3_CBC_WITH_MD5 */ { diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index 93d1cbe438..33c52ac5bf 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -1896,6 +1896,13 @@ SSL_CTX *SSL_CTX_new(const SSL_METHOD *meth) */ ret->options |= SSL_OP_LEGACY_SERVER_CONNECT; + /* + * Disable SSLv2 by default, callers that want to enable SSLv2 will have to + * explicitly clear this option via either of SSL_CTX_clear_options() or + * SSL_clear_options(). + */ + ret->options |= SSL_OP_NO_SSLv2; + return (ret); err: SSLerr(SSL_F_SSL_CTX_NEW, ERR_R_MALLOC_FAILURE); -- 2.25.1