What do the SSL/TLS checks cover?

Short for Browser Exploit Against SSL/TLS, BEAST is a browser exploit targeting SSL/TLS. This attack leverages weaknesses in the underlying encryption algorithm to exploit the SSL/TLS protocol. The attack can enable an attacker to decrypt traffic in certain circumstances.

Primarily this is a client side issue mitigated by ensuring end-users are running a modern and fully patched Web browser that includes protection against the BEAST attack. Major browser vendors have added workarounds to mitigate the attack. Server-side, it is recommended to disable TLS1.0 whenever possible. If any server-side mitigations are found, this issue is considered an 'informational' vulnerability.

Browser Reconnaissance and Exfiltration via Adaptive Compression of Hypertext (BREACH) is a known-plaintext attack against SSL connections over compressed HTTP based on the CRIME attack technique.

Disable HTTP compression if possible (however this will have performance implications).  If not possible, ensure that appropriate CSP and CSRF tokens are implemented.",

Compression Ratio Info-leak Made Easy (CRIME) is an attack on any SSL/TLS implementation using TLS-Compression. An attacker can deduce that Session cookie and header data with some effort and Man-In-The-Middle (MiTM) techniques.

Disable TLS Compression server side and/or ensure end users are running a modern and fully patched Web browser that includes protection against the CRIME attack.

Padding Oracle On Downgraded Legacy Encryption (POODLE) is a man-in-the-middle exploit which takes advantage of client fallback to SSL 3.0. There is also a variant of this attack based on the incorrect implementation of CBC ciphers in TLS.

Disable SSLv3. Enable TLS_FALLBACK_SCSV on your server, and update your server software or cryptography library.

Weak ciphers increase the likelihood of a cryptographic stream being decrypted.  This item is "informational" if some, but less than half, of the cipher suites are identified to be weak ciphers.

Use modern cipher suites for new versions of TLS protocol, and for older versions of TLS (TLS1.0) use cipher suites with keys that are 128-bit or larger. If using DH keys, produce your own server DH exchange keys that are larger than 2048 and don’t use any of the well-known DH-Keys. For ECDH refrain from using NSA related curves and instead use new curves such as Bernstein curves.",

The ChangeCipherSpec (CCS) injection vulnerability is a vulnerability in the OpenSSL library that could allow for a man-in-the-middle (MiTM) attack against an encrypted connection.

Update your server software or cryptographic library.

Many old cryptographic libraries do not properly associate renegotiation handshakes with an existing connection, which allows man-in-the-middle attackers to insert data into SSL/TLS sessions.

Update your server or appliance software.

SWEET32 is an attack on 64-bit cipher suites allowing successful cryptanalysis of data if a very large data set is sent to your server in the same session.",

Disable 64-block ciphers like 3DES. If this is not possible, close a TLS session after 200MB or less or renegotiate TLS (which can be technically challenging).",

Assessing the integrity of all certificates in the chain.

Identifying signatures derived from SHA-1 or earlier algorithms. 

We identify and assess key lengths. 

While there is no known weakness in ECC, there are some 'known curves' for which compromising information is available.  

If we can't reach the revocation providing service then we can't check the validaty of the certificate.

X509 v3 supports multiple common names and/or Subject alternative names. From TLS1.0 common names and alternative names are documented on how they should be implmeneted to define hostname, alternative names and common name, so as to include wildcards to define all sub domains.

As of April 2018 all SSL certificates not only EV, OV or DV certificates are mandated to have a certificate transparency record. 

Blacklisted certificates are certificates or CA that have been blacklisted for many reasons like hosting malware or key exposure.

The DNS-Based Authentication of Named Entities (DANE) specification introduces the "TLSA" resource record type.  TLSA records associate a certificate or a public key of an end-entity or a trusted issuing authority with the corresponding Transport Layer Security (TLS).  .

Enabling TLS_FALLBACK_SCSV will prevent some MiTM attack from degrading the connection cipher suites after agrrement.  This setting will help prevent attacks like POODLE.  

Forward secrecy is done by enabling DHE and ECDHE and prioritizing these Cipher suites over other suites. 

DNS CAA records gives a second channel for validating the CA of the certificate, which can be a useful validation mechnism for certificates.