While it seems that almost all certificates include a subjectAltName extension, need to allow for the possibility that the two certificates being compared don't have subjectAltName extensions.
Since some OpenSSL binaries, namely Gentoo’s, don’t support bracketed
IPv6 addresses but unbracketed ones, specified as the -connect option,
the UNBRACKETED_IPV6 environment variable can be set to true for
disabling the automatic addition of brackets around IPv6 addresses on
such platforms.
While standard OpenSSL requires the literal IPv6 address enclosed
in [brackets], standard DNS lookup tools don’t support the additional
characters. Before making reverse PTR lookups, these brackets have to
be removed from the IPv6 addresses.
When run_rc4() is run with the "--show-each" option, but without the "--wide" option, a list of all RC4 ciphers is printed, without any distinction between those that are supported by the server and those that are not. This is the same issue I noted in #332 for run_pfs().
In run_pfs(), the displayed output was corrected, but all ciphers were still being added to $pfs_ciphers, so the list of supported PFS ciphers sent to fileout() was incorrect.
This PR fixes both issues.
When certificate_info() is trying to determine what type of public key the server has so that it can determine whether the key size is acceptable, it sometimes looks at $cert_sig_algo rather than $cert_key_algo. This PR fixes that and also adds support for DSA public keys.
The dec2hex() was actually converting from hex to decimal. Since it was only being used in one place, and wasn't really needed there, I just deleted it.
Revised parse_tls_serverhello() to more carefully check the response for errors, and to provide for more flexibility (e.g., if handshake messages are split across multiple fragments).
The new test in PR #346 sends a TLSv1.4 ClientHello, so socksend_tls_clienthello() needs to include the signature algorithms extension if $tls_low_byte >= 3 rather than only if it is equal to 3.
One server I am testing responds to an SSLv3 ClientHello with TLSv1.2. If tls_sockets is being used, then testssl.sh responds with "#FIXME: downgraded. still missing a test case here." This PR fixes that, and in general checks the responses in run_protocols() more closely.
If tls_sockets is being used and the connection fails even though the server supports an earlier version of SSL/TLS, then it flags an error. If tls_sockets returns 2, then it verifies that $DETECTED_TLS_VERSION is equal to the highest version number supported by the server (that is also less than the version number in the ClientHello).
In addition, in order to test servers' support for version negotiation, it adds a new test that sends a TLSv1.4 ClientHello and verifies that the server responds with the highest version number that it supports. (This test only runs if both $using_sockets and $EXPERIMENTAL are true and server actually supports some version of SSL/TLS other than SSLv2.)
Changed to only include the signature algorithms extension for TLSv1.2, since RFC 5246 says:
Note: this extension is not meaningful for TLS versions prior to 1.2.
Clients MUST NOT offer it if they are offering prior versions.
However, even if clients do offer it, the rules specified in [TLSEXT]
require servers to ignore extensions they do not understand.
Inclusion of the extension for TLS 1.1 didn't seem to cause any harm, but it seems better to follow the RFC and not include it for TLSv1.0 or TLSv1.1.
RFC 7685 notes that there is at least one TLS implementation that hangs if the client sends a ClientHello with a TLSCiphertext.length between 256 and 511 bytes, and so the padding extension was defined in order to get around this bug. (OpenSSL s_client includes this extension when the -bugs option is used.) So, I changed socksend_tls_clienthello() to include the padding extension if the CLientHello would have a length between 256 and 511 bytes, making the padding extension just large enough to make the ClientHello 512 bytes.
I also fixed a typo (a missing "0x") in the check for whether any ECC ciphers are included in the Client Hello.
In doing some work on cipher_pref_check() I noticed that it was failing on SSLv2 since the call to "$OPENSSL s_client" includes SNI. I've also noticed in my testing that "$OPENSSL s_client" will not connect to an SSLv2-only server unless the "-ssl2" flag is included. So, I carefully checked each call to "$OPENSSL s_client" in the program (other than in run_allciphers and run_cipher_per_proto, since those functions are already addresses in PR #341) to see whether they would inappropriate fail with an SSLv2-only (or SSLv3-only) server.
As a general rule, if the call doesn't currently include the protocol, then I added "-ssl2" if $OPTIMAL_PROTO is "-ssl2", indicating that the server only supports SSLv2, and I removed any $SNI if a protocol is specified if a protocol is specified and it is either SSLv2 or SSLv3.
I tested it on an SSLv2-only server, and the results are much better. I also tested it on a collection of other servers, none of which support SSLv2, and the results are the same as with the current code.
The only thing I haven't been able to test is how the revised code works when the "--starttls" option is used. I don't believe the changes I made would cause anything to break in that case, but I also don't think code will work any better in that case, if the server only supports SSLv2. Of course, since no server should support SSLv2 (let alone only SSLv2), it shouldn't really be an issue.
One thing that I did not change, but that I do not understand; why does determine_optimal_proto() try the protocols in the order "-tls1_2 -tls1 -ssl3 -tls1_1 -ssl2" rather than "-tls1_2 -tls1_1 -tls1 -ssl3 -ssl2"? Doesn't the current ordering imply that TLS v1.0 and SSLv3 are better than TLS v1.1?
Versions of OpenSSL prior to 1.1.0 ignore the options "-tls1_1" and "-tls1_2". So, a call of the form "$OPENSSL ciphers -tls1_2 -V 'ALL:COMPLEMENTOFALL:@STRENGTH' would list all supported ciphers (including SSLv2 ciphers), not just ciphers appropriate for TLS1.2.
This changes the code to use "-tls1" instead of "-tls1_1" or "-tls1_2" if a version of OpenSSL other than 1.1.0 is being used.
David Cooper
Dirk
typingArtist