Title

Public web servers must use TLS if authentication is required. (Cat II impact)

Discussion

Transport Layer Security (TLS) is optional for a public web server. However, if authentication is being performed, then the use of the TLS protocol is required. Without the use of TLS, the authentication data would be transmitted unencrypted and would become vulnerable to disclosure. Using TLS along with DoD PKI certificates for encryption of the authentication data protects the information from being accessed by all parties on the network. To further protect the authentication data, the web server must use a FIPS 140-2 approved TLS version and all non-FIPS-approved SSL versions must be disabled. FIPS 140-2 approved TLS versions include TLS V1.0 or greater. NIST SP 800-52 specifies the preferred configurations for government systems.

Check Content

Verify that the ssl module is loaded. Open a command prompt and run the following command from the directory when httpd.exe is located: httpd –M This will provide a list of all the loaded modules. Verify that the “ssl_module” is loaded. If this module is not found, this is a finding. After determining that the ssl module is active, locate the Apache httpd.conf file. If unable to locate the file, perform a search of the system to find the location of the file. Open the httpd.conf file with an editor such as notepad, and search for the following uncommented directives: SSLProtocol & SSLEngine Review the SSL sections of the httpd.conf file, all enabled SSLProtocol directives for Apache 2.2.22 and older must be set to “TLSv1”. Releases newer than Apache 2.2.22 must be set to "ALL -SSLv2 -SSLv3". If SSLProtocol is not set to the proper value, this is a finding. For all enabled SSLEngine directives ensure they are set to “on”. Both the SSLProtocol and SSLEngine directives must be set correctly or this is a finding. NOTE: In some cases web servers are configured in an environment to support load balancing. This configuration most likely utilizes a content switch to control traffic to the various web servers. In this situation, the TLS certificate for the web sites may be installed on the content switch versus the individual web sites. This solution is acceptable as long as the web servers are isolated from the general population LAN. We do not want users to have the ability to bypass the content switch to access the web sites.

Fix Text

Edit the httpd.conf file to load the ssl_module; set the SSLProtocol to "ALL -SSLv2 -SSLv3" and set the SSLEngine to On.

Additional Identifiers

Rule ID: SV-28565r2_rule

Vulnerability ID: V-13694

Group Title: WG342

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.