{"description": "Using Kerberos on all exported mounts prevents a malicious client or user from\nimpersonating a system user. To cryptography authenticate users to the NFS server,\nadd <tt>sec=krb5:krb5i:krb5p</tt> to each export in <tt>/etc/exports</tt>.", "rationale": "When an NFS server is configured to use AUTH_SYS a selected userid and groupid are used to handle\nrequests from the remote user. The userid and groupid could mistakenly or maliciously be set\nincorrectly. The AUTH_GSS method of authentication uses certificates on the server and client\nsystems to more securely authenticate the remote mount request.", "severity": "medium", "references": {"cis-csc": ["1", "12", "14", "15", "16", "18", "3", "5"], "cobit5": ["DSS05.04", "DSS05.10", "DSS06.10"], "hipaa": ["164.308(a)(4)(i)", "164.308(b)(1)", "164.308(b)(3)", "164.310(b)", "164.312(e)(1)", "164.312(e)(2)(ii)"], "isa-62443-2009": ["4.3.3.6.1", "4.3.3.6.2", "4.3.3.6.3", "4.3.3.6.4", "4.3.3.6.5", "4.3.3.6.6", "4.3.3.6.7", "4.3.3.6.8", "4.3.3.6.9", "4.3.3.7.3"], "isa-62443-2013": ["SR 1.1", "SR 1.10", "SR 1.2", "SR 1.5", "SR 1.7", "SR 1.8", "SR 1.9", "SR 2.1"], "iso27001-2013": ["A.18.1.4", "A.6.1.2", "A.9.1.2", "A.9.2.1", "A.9.2.3", "A.9.2.4", "A.9.3.1", "A.9.4.1", "A.9.4.2", "A.9.4.3", "A.9.4.4", "A.9.4.5"], "nist": ["CM-7(a)", "CM-7(b)", "CM-6(a)", "IA-2", "IA-2(8)", "IA-2(9)", "AC-17(a)"], "nist-csf": ["PR.AC-4", "PR.AC-7"], "srg": ["SRG-OS-000480-GPOS-00227"]}, "control_references": {}, "components": [], "identifiers": {}, "ocil_clause": "the setting is not configured, has the 'sys' option added, or does not have all Kerberos options added", "ocil": "To verify the <tt>sec</tt> option is configured for all NFS mounts, run the following command:\n<pre>$ grep \"sec=\" /etc/exports</pre>\nAll configured NFS exports should show the <tt>sec=krb5:krb5i:krb5p</tt> setting in parentheses.\nThis is not applicable if NFS is not implemented.", "oval_external_content": null, "fixtext": "", "checktext": "", "vuldiscussion": "", "srg_requirement": "", "warnings": [], "conflicts": [], "requires": [], "policy_specific_content": {"stig": {"srg_requirement": "Ubuntu 22.04 must be configured so that the Network File System (NFS) is configured to use RPCSEC_GSS.", "vuldiscussion": "When an NFS server is configured to use AUTH_SYS a selected userid and groupid are used to handle\nrequests from the remote user. The userid and groupid could mistakenly or maliciously be set\nincorrectly. The AUTH_GSS method of authentication uses certificates on the server and client\nsystems to more securely authenticate the remote mount request.", "checktext": "Verify Ubuntu 22.04 has the \"sec\" option is configured for all NFS exports with the following command:\n\nNote: If the system does not have any filesystems mounted for NFS export this requirement is Not Applicable.\n\n$ grep \"sec=\" /etc/exports\n\n192.168.17.7:/mnt/export /data1 nfs4 rw,sync ,soft,sec=krb5p:krb5i:krb5\n\nIf the system is exporting file systems via NFS and has the sec option without the \"krbp:krb5i:krb5\" settings, the \"sec\" option has the \"sys\" setting, or the \"sec\" option is missing, this is a finding.", "fixtext": "Update the \"/etc/fstab\" file so the option \"sec\" is defined for each NFS mounted file system and the \"sec\" option does not have the \"sys\" setting.\n\nEnsure the \"sec\" option is defined as \"krb5p:krb5i:krb5\"."}}, "platform": "system_with_kernel", "platforms": ["system_with_kernel"], "sce_metadata": {}, "inherited_platforms": [], "cpe_platform_names": ["system_with_kernel"], "inherited_cpe_platform_names": [], "bash_conditional": null, "fixes": {}, "title": "Use Kerberos Security on All Exports", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/services/nfs_and_rpc/nfs_configuring_servers/use_kerberos_security_all_exports/rule.yml", "template": null}