`std_cipherlists()` uses `has_server_protocol()` to determine whether to test for ciphers using SSLv2. However, this was resulting in false negatives due to #759. This PR removes the `has_server_protocol()` check so that SSLv2 is checked whenever the connection attempt with the TLSv1.2 ClientHello failed.
This PR fixes the extraction of the cipher suites in SSLv2 ClientHellos in `client_simulation_sockets()`. Since `client_simulation_sockets()` can only handle SSLv3 and above ServerHellos, it removes any SSLv2 ciphers and converts the other cipher from 3-byte format to 2-byte format.
If vulnernable to POODLE and has no TLS_FALLBACK_SCSV ==> HIGH.
If only run the fallback check and it has none, still label it as MEDIUM but issue
a clear warning that test under this circumstances is incomplete.
This PR adds the same additional check to `client_simulation_sockets()` as was previously added to `tls_sockets()`. It extracts the list of cipher suites offered from each ClientHello and passes the list to `parse_tls_serverhello()` so that `parse_tls_serverhello()` can check that the cipher offered in the ServerHello was included in the ClientHello.
This assumes that a real client would abort the connection if it was presented with a cipher in the ServerHello that it didn't offer in its ClientHello.
Unfortunately, most categories were passing incorrectly, since a
tls_socket() error was interpreted as a success for many of the cases.
Now we explicitely check for the known yaSSL failure and raise a warning
that the test is inconclusive.
New output against --starttls=mysql looks like:
Testing ~standard cipher categories
-----------------------------------
NULL ciphers (no encryption) SERVER_ERROR: test inconclusive due to MySQL Community Edition (yaSSL) bug.
Anonymous NULL Ciphers (no authentication) SERVER_ERROR: test inconclusive due to MySQL Community Edition (yaSSL) bug.
Export ciphers (w/o ADH+NULL) SERVER_ERROR: test inconclusive due to MySQL Community Edition (yaSSL) bug.
LOW: 64 Bit + DES encryption (w/o export) offered (NOT ok)
Weak 128 Bit ciphers (SEED, IDEA, RC[2,4]) SERVER_ERROR: test inconclusive due to MySQL Community Edition (yaSSL) bug.
Triple DES Ciphers (Medium) offered
High encryption (AES+Camellia, no AEAD) offered (OK)
Strong encryption (AEAD ciphers) SERVER_ERROR: test inconclusive due to MySQL Community Edition (yaSSL) bug.
Partial workaround for #793
According to a discussion thread on the IETF TLS WG mail list (see https://www.ietf.org/mail-archive/web/tls/current/msg19720.html), there is at least one TLS server that will fail if the last extension in the ClientHello has contains extension_data of length 0.
Currently, `tls_sockets()` will create such a ClientHello if:
* The padding extension is included, and the length of the ClientHello without the padding data would be between 508 and 511 bytes.
* No padding extension is included, and the caller provided `$extra_extensions` in which the last extension in `$extra_extensions` is empty.
* No padding extension is included, `$extra_extensions` is empty, no ECC cipher suites are offered, and the ClientHello is for TLSv1.1 or below (in this case the next protocol extension would be that last one).
This PR avoids the server bug (in nearly all cases) by ensuring the the padding extension (when present) always contains at least one byte, and by ensuring that when the padding extension is not present that the (non-empty) heartbeat extension is the last extension.
This PR does leave one possible scenario in which the last extension would be empty. If the caller provides an `$extra_extensions` in which the last extension in `$extra_extensions` is empty, `tls_sockets()` does not add a padding extension (or a padding extension is included in `$extra_extensions`), and `$extra_extensions` includes a heartbeat extension, then the last extension in the ClientHello would be empty. This, however, is a highly unlikely scenario, and certainly there are currently no such calls to `tls_sockets()` in testssl.sh.
Until the content is finalized the plan is to keep it in MD format.
For medium terms it is something which needs to be reconsidered
as markdown as the source format for documentation has too many limits.
Happy for suggestions here.
In the meantime here's what needs to be done:
* finalizing (see comments)
* proofreading 1: accuracy, logic, more content related
* proofreading 2: grammar, spelling
* more? pls let me know
Another yaSSL server incompatiblity. MySQL protects against CCS
Injection by erroring if it sees to CCS requests before the handshake
completes. But instead of returning a TLS alert, it seems to error up
the stack to MySQL which returns it's own error message.
Debug output looks like:
---
sending client hello,
reading server hello
1st reply:
sending payload #2 with TLS version x03, x02:
tls_content_type: 16 | tls_protocol: 0000 | byte6: 04
2nd reply:
00000000 16 00 00 02 ff 13 04 23 30 38 53 30 31 42 61 64 |.......#08S01Bad|
00000010 20 68 61 6e 64 73 68 61 6b 65 | handshake|
0000001a
test failed, probably read buffer too small (16000002FF1304)
---
This patch adds a custom check for this MySQL specific error, as far
down in the error check path as I can.
If $PROTOS_OFFERED was empty, and thus the protocols unknown, this
function would return true for any protocol you passed it. This caused
most callers to assume TLS1.0, even if the server didn't offer it.
Instead return false and make the caller do an extra lookup.
As reported in #782, some servers will return a ServerHello with a cipher not listed in the ClientHello rather than than return an Alert, if the server does not support any of the ciphers listed in the ClientHello.
This commit modifies `tls_sockets()` to check whether the cipher in the ServerHello was one included in the ClientHello and to fail if it wasn't.
This is the simplest direct socket implementation of the MySQL STARTTLS
protocol.
This is a binary protocol, so it requires a new stream based send
(instead of the current line based send).
In `run_hpkp()` there is a call to `$OPENSSL s_client` that uses `${sni[i]}` as one of the command line options, but `sni` is not defined. My guess is that this was a copy/paste error from `run_client_simulation()`, which is the only function where an `sni` array is defined.
I am guessing that the intention was to use `$SNI` in `run_hpkp()`.
David Cooper
Dirk
Steven Danneman