{"description": "Kerberos may rely on key distribution functions unapproved by Common Criteria.\nTo prevent using Kerberos by system daemons, remove the Kerberos keytab files, especially\n<tt>/etc/krb5.keytab</tt>.", "rationale": "Some key derivation functions (KDF) in Kerberos are not FIPS-compatible", "severity": "medium", "references": {"srg": ["SRG-OS-000120-GPOS-00061"], "ism": ["0418", "1055", "1402"]}, "control_references": {"ism": ["0418", "1055", "1402"]}, "components": [], "identifiers": {}, "ocil_clause": "a keytab file is present on the system", "ocil": "Run the following command to see if there are some keytabs\nthat would potentially allow the use of Kerberos by system daemons.\n<pre>$ ls -la /etc/*.keytab</pre>\nThe expected result is\n<pre>ls: cannot access '/etc/*.keytab': No such file or directory</pre>", "oval_external_content": null, "fixtext": "Configure Ubuntu 22.04 to prevent system daemons from using Kerberos for authentication.\n\nRemove any files with the .keytab extension from the operating system.\nrm -f /etc/*.keytab", "checktext": "", "vuldiscussion": "", "srg_requirement": "", "warnings": [], "conflicts": [], "requires": [], "policy_specific_content": {"stig": {"srg_requirement": "Ubuntu 22.04 must prevent system daemons from using Kerberos for authentication.", "fixtext": "Configure Ubuntu 22.04 to prevent system daemons from using Kerberos for authentication.\n\nRemove any files with the .keytab extension from the operating system.\n\nrm -f /etc/*.keytab\n\nIf Kerberos authentication is a mission requirement, document its use and justification with the ISSO.", "checktext": "Note: If there is an operational requirement for Kerberos implementation, and it is documented with the ISSO, this control is Not Applicable.\n\nVerify that Ubuntu 22.04 prevents system daemons from using Kerberos for authentication with the following command:\n\n$ sudo ls -al /etc/*.keytab\n\nls: cannot access '/etc/*.keytab': No such file or directory\n\nIf this command produces any \"keytab\" file(s), this is a finding.", "vuldiscussion": "Unapproved mechanisms used for authentication to the cryptographic module are not verified; therefore, cannot be relied upon to provide confidentiality or integrity and DOD data may be compromised.\n\nUbuntu 22.04 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules.\n\nThe key derivation function (KDF) in Kerberos is not FIPS compatible. Ensuring the system does not have any keytab files present prevents system daemons from using Kerberos for authentication. A keytab is a file containing pairs of Kerberos principals and encrypted keys.\n\nFIPS 140-3 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DOD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general-purpose computing system."}}, "platform": null, "platforms": ["krb5_server_older_than_1_17-18 and krb5_workstation_older_than_1_17-18"], "sce_metadata": {}, "inherited_platforms": ["system_with_kernel"], "cpe_platform_names": ["krb5_server_older_than_1_17-18_and_krb5_workstation_older_than_1_17-18"], "inherited_cpe_platform_names": ["system_with_kernel"], "bash_conditional": null, "fixes": {}, "title": "Disable Kerberos by removing host keytab", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/services/kerberos/kerberos_disable_no_keytab/rule.yml", "template": null}