It turns out that, for probably a long time, we have reported an
incorrect version when parsing an SSLv2 client hello. We always reported
this as SSLv2, no matter which version the client hello actually
contained.
This bug probably went unnoticed for a long time, as SSLv2 is
essentially unused nowadays, and as this field does not show up in the
default logs.
This was found due to a baseline difference when writing the Spicy SSL
analyzer.
The dpd signature missed a few cases that are used for TLS 1.3,
especially when draft versions (which are all that we are seeing at the
moment) are being negotiated.
This fix mostly allows draft versions in the server hello (identified by
7F[version]; since we do not know how many drafts there will be, we are
currently allowing a rather safe upper limit.
The alert in this case is caused by the server name in the SNI not being
recognized by the server, which triggers an alert. Since the server is
an apache, and this might happen reasonably often, the new signature
allows one TLS alert before the server hello is expected.
