This PR removes the changes that were added in #1113. As noted in the conversation for #1113, it was eventually determined that the actual bug was related to the first message fragment being too short rather than the overall length of the message. So, the warning message that is displayed by the code is misleading. In addition, if changes are made to avoid TCP fragmentation, then this code will no longer even test for intolerance to short message fragments.
As @tomato42 pointed out in #1113 '\x0a' causes the printf buffer
to flush before all data was sent. As a result any '\x0a' in
a ClientHello causes a new TCP fragment.
This commit changes all TCP sockets write to use an external
printf if available which doesn't show this behaviour, see #1130.
It was checked against wireshark.
The external printf was available for Linux, FreeBSD 9 and OpenBSD,
so I do not expect any problems with MacOS X either.
There might be further solutions like 'stdbuf' or 'dd' which
are shown in #1130.
This commit removes the '0a' character from public keys used in the key_share extension. New key pairs were created by repeatedly generating new keys until one was found that had no '0a' characters in the public key.
As noted in #1130, the current implementation of socksend_tls_clienthello() results in packets being fragmented wherever a '0a' character appears in the message. This cannot be avoided, but there are a few places where a '0a' character appears in which the character could easily be replaced:
* In the session_id for a TLSv1.3 ClientHello.
* In the 32-byte client random value
* In any public key sent in the key_share extension
This PR removes those uses of the '0a' character. While this does not do much to address the problem, it does result in a slight reduction in the amount of fragmentation of messages.
This PR is an attempt to fix the problem identified in #1118.
Currently, get_cipher() and get_protocol() attempt the extract the cipher and protocol from the SSL-Session information printed by OpenSSL s_client. This does not always work for TLSv1.3, however, since OpenSSL 1.1.1 will only print SSL-Session information for a TLSv1.3 connection if the server sends New Session Ticket. If the server doesn't, then get_cipher() and get_protocol() return empty strings.
For TLSv1.3 connections in which the server does not send a New Session Ticket, there seems to be only one other source for this information. A line of the form:
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
[Note that "New" would be "Reused" if the connection were created via session resumption.]
The use of this line seems to be okay for extracting the negotiated cipher, but it cannot be used in general to extract the negotiated protocol. The reason is that this line is created as follows:
c = SSL_get_current_cipher(s);
BIO_printf(bio, "%s, Cipher is %s\n",
SSL_CIPHER_get_version(c), SSL_CIPHER_get_name(c));
While the cipher that is printed seems to be the negotiated cipher, the protocol that is printed is "the SSL/TLS protocol version that first defined the cipher." Since TLS 1.3 ciphers may only be used with TLS 1.3, protocol version printed on this line may be accepted as the negotiated protocol if and only if it is "TLSv1.3."
This PR addresses the problem by modifying get_cipher() and get_protocol() to check the "New, ..., Cipher is ..." line if lines from SSL-Session ("Cipher : ...", "Protocol : ...") cannot be found. In the case of get_protocol() the protocol on the "New, ..., Cipher is ..." will be accepted only if the protocol is "TLSv1.3" and the cipher is a TLSv1.3 cipher.
This PR also adds a check for the "New, ..., Cipher is ..." to sclient_connect_successful(). If this line is present, and the protocol and cipher are not "(NONE)", then this is accepted as an indication that the connection was successful even if the "Master-Key" line does not appear. It is not clear whether this extra test is needed, however, as sclient_connect_successful() will not even look at the text in the output of OpenSSL s_client if function's return value is 0, and OpenSSL s_client should return 0 if the connection was successful.
Most of the curves that were defined for the supported_groups extension in RFC 4492 have been deprecated in RFC 8422 and RFC 8446. Appendix B.3.1.4 of RFC 8446 says that these deprecated values "are used in previous versions of TLS and MUST NOT be offered or negotiated by TLS 1.3 implementations."
According to a recent discussion on the TLS mail list (see, for example, https://www.ietf.org/mail-archive/web/tls/current/msg26974.html and https://www.ietf.org/mail-archive/web/tls/current/msg26980.html) a TLS 1.3 server implementation may choose to reject a TLS 1.3 ClientHello simply because the ClientHello offers one or more of the deprecated curves.
This PR address this issue by no longer offering the deprecated curves in TLS 1.3 ClientHello messages. This only affects run_pfs(), since socksend_tls_clienthello() already does not offer the deprecated curves in TLS 1.3 ClientHello messages.
The change in this PR has no affect on the testing of servers that do not support TLS 1.3. For those that do support TLS 1.3, only the 5 non-deprecated curves are tested with TLS 1.3, but all 30 curves are tested with TLS 1.2.
This PR reduces the number of public keys that are included in the key_share extension for a TLS 1.3 ClientHello.
When creating the key_share extension for a TLS 1.3 ClientHello, generate_key_share_extension() generally omits the public keys for larger finite-field groups (ffdhe3072, ffdhe4096, ffdhe6144, and ffdhe8192) so that the extension will not be overly large. However, the extension that it creates is still much larger than what is created by other software.
For a generic TLS 1.3 ClientHello, socksend_tls_clienthello() offers 7 groups in the supported_groups extension (P-256, P-384, P-521, X25519, X448, ffdhe2048, ffdhe3072) and 6 public keys in the key_share extension (P-256, P-384, P-521, X25519, X448, ffdhe2048). While the largest public key is omitted, this still creates a 665 byte key_share extension.
By contrast, Firefox offers 6 groups in the supported_groups extension (X25519, P-256, P-384, P-521, ffdhe2028, ffdhe3072), but only includes two public keys in the key_share extension (X25519, P-256). OpenSSL 1.1.1 offers 5 groups in the supported_groups extension (X25519, P-256, P-384, P-521, X448) and only includes one key in the key_share extension (X25519). Chrome offers 3 groups in the supported_groups extension (X25519, P-256, P-384) and only includes one key in the key_share extension (X25519).
Following the examples of OpenSSL, Firefox, and Chrome, this PR changes generate_key_share_extension() to include at most two public keys in the key_share extension. In general it will offer the public keys for the first two groups that appear in the supported_groups extension. However, it will still exclude the public key for any ffdhe group larger than ffdhe2048 unless that group appears first in the supported_groups extension.
In most cases this change will simply result in the ClientHello message being smaller. In some unusual cases, this change will force a second round-trip, with the server sending a HelloRetryRequest in order to ask for the key_share that it needs, but this will not affect the results of the testing.
In run_grease() there is a mismatch between the severity level of finds as printed and as sent to fileout(). Problems are labeled as medium when printing, but as CRITICAL in the call to fileout(). This PR fixes the problem by changing CRITICAL to MEDIUM.
This commit fixes#1123 where a security header containing an asterix lead
to a local filename expansion which was included in the CSV file output.
A new function fileout_csv_finding() addresses this.
Also if "$GIVE_HINTS" isn't true the headline and each line in the CSV file doesn't include
anymore the word hint -- which is more consistent with the JSON output.
As described in #1113, some servers will fail if the length of the ClientHello message is 522, 778, 1034, ... bytes (i.e., if length mod 256 = 10) or 526, 782, 1038, ... bytes (i.e., if length mod 256 = 14). This commit avoid this issue for normal testing by adding a 5-byte padding extension to the message if the length would otherwise be one of these lengths.
socksend_tls_clienthello() does not calculate the length of the ClientHello message in the case of a TLS 1.3 ClientHello, since it does not take into account the inclusion of a 32-byte session id. The length value that is being calculated incorrectly is only used to determine whether to include a padding extension, and if so, how long that extension should be.
This fix was previously included as part of PR #1120, since a correct length calculation is needed to avoid a ClientHello length such that length mod 256 = 10, but I removed it from that PR and am making it a separate PR, since it is a bug that should be fixed even if #1120 isn't adopted.
This commit updates the size bug GREASE test in a few ways:
* It removes the changes to socksend_tls_clienthello() - these will be submitted as a separate PR.
* It adds a test for a ClientHello message length of 266 bytes, but only if the server can generally handle messages with lengths between 256 and 511 bytes.
* It corrects the calculation of the length of the padding extension in cases in which a TLS 1 or TLS 1.1 ClientHello is being sent.
Just as some servers will fail if the length of the ClientHello is between 256 and 511 bytes (see RFC 7685), it seems that some servers (or a middlebox sitting in front of the servers) will fail if the length of the ClientHello is 522, 778, 1034, ... bytes in length (i.e., if length mod 256 = 10). I have also encountered one server that will also fail if the length of the ClientHello is 526, 782, 1038, ... bytes in length (i.e., if length mod 256 = 14).
In the case of that one server, the first ClientHello sent by run_pfs() was exactly 1038 bytes, and so run_pfs() was reporting that the server didn't support any PFS ciphers even though it did..
This PR addresses the problem in two ways. First, it modifies socksend_tls_clienthello() so that if the length of the ClientHello would be more than 511 bytes and length mod 256 would be 10 or 14, it adds a 5-byte padding extension in order to ensure that the final length of the ClientHello will not be a length that could trigger the bug.
Second, this PR adds a test to run_grease() to send ClientHello messages of the exact lengths that do trigger the bug so that users can be made aware that their servers have the problem.
In cases where a finding was empty (error condition), the JSON output
wasn't valid because the finding wasn't printed to file.
This commit makes sure that always a finding is printed,
also if it is empty.
FIX#1112
As #1119 noted, there's a warning for users with an OpenSSL 1.1.1
config file because of #1117 / #1098 .
This commit suppresses the warning on the screen if a config file
from OpenSSL 1.1.1 was detected (kludge from
b524b808a1).
This addresses a bug where openssl s_client connects hiccuped
because of newer config files which our openssl 1.0.2 couldn't
swallow.
It appeared first on Debian.
FIX#1117FIX#1098
RFC 8446 specifies the following for the list of certificates provided by the server:
The sender's certificate MUST come in the first
CertificateEntry in the list. Each following certificate SHOULD
directly certify the one immediately preceding it.
In RFC 5246 the "SHOULD" was a "MUST". This commit adds a check of whether the certificates provided by the server are in the correct order and issues a low severity warning if they are not.
As mentioned in #1106 proxying ocsp protocol doesn't work (yet)
This commit notifies the user that it is not possible. One
can ignore that and try by supplying IGN_OCSP_PROXY=true.
It also fixes a typo I probably introduced (pVULN_THRESHLD).
The standard separator after $FNAME_PREFIX is now '-'.
You can as well supply a different <fname_prefix> ending in '.', '_' or ',' , then
no no additional '-' will be appended.
Also a small bash function get_last_char() has been introduced which returns
the last char from a supplied string.
... for curl, wget and sockets. Tested and worked.
Furthermore: fd_socket() now is a bit more injection safe as
an echo statement was exchange by printf. For possible future
changes fd_socket now also has and arg1 for the file descriptor.
... previously it depended on the order of DNS replies otherwise. This was
one outcome of discussion in #1026 where it seemed more logical
to pick an IPv6 address as opposed to an abitrary (v4/v6) address.
This PR fixes checks where those two cmdline options were supplied
but errorneously also the IPv4 address was tested.
It also lables supplied IPv6 addresses as AAAA records
instead of A records.
Still, determine_ip_addresses() has space for improvements.
Some comparisons fixed strings popped up during debugging were polished
to avoid internal quoting
[[ $VAR == "teststr" ]]
will be otherwise expanded to
[[ $VAR == \t\e\s\t\s\t\r ]]
David Cooper
Dirk