4.4.1.7 Ensure secure RPC authentication is enabled

Information

To enhance server-client authentication ensure that the secure option is selected for every export.

RPC is a protocol used by NFS to communicate requests between hosts. Secure NFS uses encryption (DES or Kerberos) to secure host authentication in RPC transactions. Secure NFS mitigates attempts by an attacker to spoof RPC requests by encrypting the time stamp in the RPC requests.

While the data is not encrypted each package is verified by a successful decryption the timestamp in every incoming RPC request. This confirmation mitigates receiving requests from untrusted or unknown hosts.

Solution

Use chnfsexp to change/validate this value for all NFS exported filesystems:

chnfsexp -d <fs> -S <sec>

The available security method options are:

- sys - UNIX authentication
- dh - DES authentication
- none - Use the anonymous ID if it has a value other than -1
- krb5 - Kerberos. Authentication only
- krb5i - Kerberos. Authentication and integrity
- krb5p - Authentication, integrity, and privacy `

Once all exported filesystems have been successfully validated or changed, re-export the filesystems and directories to activate the new options:

exportfs -a

See Also

https://workbench.cisecurity.org/benchmarks/10385

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-7b.

Plugin: Unix

Control ID: e52edd3dd2b20d87b990761d4188e28b47ec0cc10f19c7a5aae17d78a4bec6cf