7.9 Ensure the TLS v1.0 Protocol Is Disabled

Information

The TLSv1.0 protocol should be disabled via the 'SSLProtocol' directive, if possible, because it is vulnerable to information disclosure.

Rationale:

The TLSv1.0 protocol is vulnerable to the BEAST attack when used in CBC mode (October 2011). Unfortunately, TLSv1.0 uses CBC modes for all of the block mode ciphers, which only leaves the RC4 streaming cipher. The RC4 cipher is also weak and is not recommended. Therefore, it is recommended that the TLSv1.0 protocol be disabled if all TLS clients support the newer TLS protocols. All major up-to-date browsers support TLSv1.1 and TLSv1.2. Ensuring that all user's browsers are configured to allow TLSv1.1 and TLSv1.2 is necessary before disabling TLSv1.0 on the Apache web server; therefore, this recommendation is a level 2 rather than a level 1. Disabling TLSv1.0 on internal-only websites is more easily accomplished when access is limited to clients with browsers controlled by the organization's policies and procedures to allow and prefer TLSv1.1 and higher.

The NIST SP 800-52r1 guidelines for TLS configuration state that servers that support government-only applications shall not support TLSv1.0 or any of the SSL protocols, while servers that support citizen or business-facing applications may be configured to support TLS version 1.0 in order to enable interaction with citizens and businesses.

Some organizations may find it helpful to implement a phased transitional plan where TLSv1.0 is not disabled, but the web server will detect browsers which do not have TLSv1.1 or newer enabled and redirect them to a web site that explains how to enable the newer TLS protocols. The redirect can be implemented using 'mod_rewrite', which can detect the protocol used and rewrite the URL to the helpful website.

Solution

Perform the following to implement the recommended state:

Search the Apache configuration files for the 'SSLProtocol' directive; add the directive if not present or change the value to 'TLSv1.1 TLSv1.2'.

See Also

https://workbench.cisecurity.org/files/2020

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-8, CSCv6|14.2

Plugin: Unix

Control ID: 253c33afe264ac50d51420dfd2c62984166628fc97751a7a66a2ad3f07909e0b