This PR address a problem in `run_drown()` when the server does not support SSLv2, but does support multiple certificates or doesn't have an RSA certificate.
One example of the problem can be seen with www.facebook.com. If `run_server_preferences()` is run before `run_drown()`, then the results of `run_drown()` are:
```
DROWN (2016-0800, CVE-2016-0703) not vulnerable on this port (OK)
make sure you don't use this certificate elsewhere with SSLv2 enabled services
https://censys.io/ipv4?q=A626B154CC65634181250B810B1BD4C89EC277CEA08D785EEBE7E768BDA7BB00 SHA256 A3F474FB17509AE6C5B6BA5E46B79E0DE6AF1BF1EEAA040A6114676E714C9965 could help you to find out
```
If only `run_drown()` is performed, then the result is:
```
DROWN (2016-0800, CVE-2016-0703) not vulnerable on this port (OK)
make sure you don't use this certificate elsewhere with SSLv2 enabled services
https://censys.io/ipv4?q=A626B154CC65634181250B810B1BD4C89EC277CEA08D785EEBE7E768BDA7BB00 could help you to find out
```
However, A626B154CC65634181250B810B1BD4C89EC277CEA08D785EEBE7E768BDA7BB00 is the fingerprint of Facebook's ECDSA certificate, not its RSA certificate.
In addition, as noted in the "FIXME," `run_drown()` will display the warning "make sure you don't use this certificate elsewhere with SSLv2 enabled services" even if the server doesn't have an RSA certificate, even though SSLv2 can only use RSA certificates.
This PR fixes this issue by only showing the warning if the server has an RSA certificate and by ensuring that the `$cert_fingerprint_sha2` used to construct the "https://censys.io/ipv4?q=..." URL only contains a single SHA256 fingerprint and that it is the fingerprint of the server's RSA certificate.
This PR modifies `cipher_pref_check()` to use `tls_sockets()`. As with similar PRs for `run_allciphers()`, `run_cipher_per_proto()`, and `run_rc4()`, it also makes use of `$OPENSSL s_client`, since `$OPENSSL s_client` is faster than `tls_sockets()`.
With this PR, `cipher_pref_check()` first uses `$OPENSSL s_client` to obtain an ordered list of ciphers. It then makes one call to `tls_sockets()` (or a few calls if proto is TLSv1.2 and `$SERVER_SIZE_LIMIT_BUG` is `true`) to find if the server supports any ciphers that are not detected by `$OPENSSL s_client`. If not, then it is done. If it finds one, then it throws out the previous results and starts over with `tls_sockets()`. [If proto is TLSv1.2 and `$SERVER_SIZE_LIMIT_BUG` is `true`, then it doesn't throw out the `$OPENSSL s_client` results. Instead, it continues with `tls_sockets()` to get the full list of supported ciphers, and then uses `tls_sockets()` to order that list.]
The result is that this PR works almost as fast as the current `cipher_pref_check()` if `$OPENSSL s_client` finds all of the supported ciphers, at the cost of a performance penalty when testing servers that support ciphers that would have otherwise been missed using just OpenSSL.
Note that in this PR I removed SSLv2 from the list of protocols tested. This is because https://community.qualys.com/thread/16255 states that "in SSLv2 the client selects the suite to use." It seems that in SSLv2, the client sends a list of ciphers that it supports, the server responds with a list of ciphers that the client and server have in common, and then "the client selects the suite to use." So, showing a cipher order for SSLv2 is a bit misleading.
As noted in #543, this PR does not modify the second part of `cipher_pref_check()`, which deals with NPN protocols.
This PR implements `run_rc4()` in a similar manner to `run_allciphers()` and `run_cipher_per_proto()` (in PR #541). The change doesn't seem to have much of an impact on speed, but when sockets are used it can detect ciphers that aren't locally supported by OpenSSL.
This PR fixes two minor bugs in run_allciphers():
* If `$SSL_NATIVE` or `$FAST` is `true`, then the cipher mapping file will not be used (unless `$OPENSSL ciphers` does not support the `-V` option), so there is no "fallback" to openssl, even if `[[ $TLS_NR_CIPHERS == 0 ]]`.
* If `$using_sockets` is `false` and `$SHOW_EACH_C` is `true`, then `ossl_supported` should be checked to see if the cipher was tested, not `TLS_CIPHER_OSSL_SUPPORTED`.
This function reorganizes `run_server_defaults()` based on the suggestion in #515.
The current `determine_tls_extensions()` is renamed to `get_server_certificate()`, and two changes are made to it:
*it no longer includes an extra call to `$OPENSSL s_client` to check for the ALPN extension; and
* rather than setting `$TLS_EXTENSIONS` to be the extensions found during this call to the function, it adds any newly found extensions to those already in `$TLS_EXTENSIONS`.
The PR then adds a new function, `determine_tls_extensions()`, which borrows some logic from the old `determine_tls_extensions()`, but this new `determine_tls_extensions()` only looks for additional TLS extensions, including ALPN.
`run_server_defaults()` makes multiple calls to `get_server_certificate()` (as it previously did to `determine_tls_extensions()`) in order to collect all of the server's certificates, and then it makes one call to `determine_tls_extensions()`, which checks for support for extensions that were not checked for by `get_server_certificate()` (e.g., ALPN, extended master secret, signed certificate timestamps).
The new `determine_tls_extensions()` will check for most of the extensions that are checked for by
`run_server_defaults()`, including the heartbeat extension, so the call to `determine_tls_extensions()` from `run_heartbleed()` will still work.
> The dh_bits are still not shown, maybe because of #531.
This PR fixes the issue of dh_bits not being shown if the cipher-mapping.txt file is missing. The problem is that the code in `parse_tls_serverhello()` that parses the ServerKeyExchange message assumes that `$rfc_cipher_suite` has the RFC version of the name the cipher suite. However, if the cipher-mapping.txt file is missing, `$rfc_cipher_suite` will have the OpenSSL name of the cipher suite. This PR changes the code to recognize either the RFC or OpenSSL names for ciphers with ephemeral DH or ECDH keys.
When `tls_sockets()` is used with the "full" option and the chosen cipher suite involves an ephemeral finite-field DH key (DH), this PR extracts the public key from the ServerKeyExchange message and adds it to `$TMPFILE`. In addition (and the primary reason for this PR), it compares the ephemeral public key's parameters to those specified in RFC 7919, and indicates whether one the groups from that RFC was used. This will allow `run_pfs()` to be extended to indicate which, if any, RFC 7919 DH groups a server supports.
David Cooper
AlGreed
Dirk
typingArtist