{"description": "All USB support can be disabled by adding the <tt>nousb</tt>\nargument to the kernel's boot loader configuration. To do so,\nadd the argument <tt>nousb</tt> to the default\nGRUB 2 command line for the Linux operating system.\nTo ensure that <tt>nousb</tt> is added as a kernel command line\nargument to newly installed kernels, add <tt>nousb</tt> to the\ndefault Grub2 command line for Linux operating systems. Modify the line within\n<tt>/etc/default/grub</tt> as shown below:\n<pre>GRUB_CMDLINE_LINUX=\"... nousb ...\"</pre>\nRun the following command to update command line for already installed kernels:<pre># update-grub</pre>", "rationale": "Disabling the USB subsystem within the Linux kernel at system boot will\nprotect against potentially malicious USB devices, although it is only practical\nin specialized systems.", "severity": "unknown", "references": {"cis-csc": ["12", "16"], "cobit5": ["APO13.01", "DSS01.04", "DSS05.03", "DSS05.04", "DSS05.05", "DSS05.07", "DSS06.03"], "hipaa": ["164.308(a)(3)(i)", "164.308(a)(3)(ii)(A)", "164.310(d)(1)", "164.310(d)(2)", "164.312(a)(1)", "164.312(a)(2)(iv)", "164.312(b)"], "isa-62443-2009": ["4.3.3.2.2", "4.3.3.5.2", "4.3.3.6.6", "4.3.3.7.2", "4.3.3.7.4"], "isa-62443-2013": ["SR 1.1", "SR 1.13", "SR 1.2", "SR 1.4", "SR 1.5", "SR 1.9", "SR 2.1", "SR 2.6"], "iso27001-2013": ["A.11.2.6", "A.13.1.1", "A.13.2.1", "A.6.2.1", "A.6.2.2", "A.7.1.1", "A.9.2.1"], "nist": ["MP-7", "CM-6(a)"], "nist-csf": ["PR.AC-3", "PR.AC-6"]}, "control_references": {}, "components": [], "identifiers": {}, "ocil_clause": "usb is enabled at boot time", "ocil": "Inspect the form of default GRUB 2 command line for the Linux operating system\nin <tt>/etc/default/grub</tt>. If it includes <tt>nousb</tt>,\nthen the parameter will be configured for newly installed kernels.\nFirst check if the GRUB recovery is enabled:\n<pre>$ sudo grep 'GRUB_DISABLE_RECOVERY' /etc/default/grub</pre>\nIf this option is set to true, then check that a line is output by the following command:\n<pre>$ sudo grep 'GRUB_CMDLINE_LINUX_DEFAULT.*nousb.*' /etc/default/grub</pre>\nIf the recovery is disabled, check the line with\n<pre>$ sudo grep 'GRUB_CMDLINE_LINUX.*nousb.*' /etc/default/grub</pre>.Moreover, current Grub config file <tt>grub.cfg</tt> must be checked. The file can be found\neither in <tt>/boot/grub</tt> in case of legacy BIOS systems, or in <tt>/boot/grub</tt> in case of UEFI systems.\nIf they include <tt>nousb</tt>, then the parameter\nis configured at boot time.\n<pre>$ sudo grep vmlinuz GRUB_CFG_FILE_PATH | grep -v 'nousb'</pre>\nFill in <tt>GRUB_CFG_FILE_PATH</tt> based on information above.\nThis command should not return any output.", "oval_external_content": null, "fixtext": "", "checktext": "", "vuldiscussion": "", "srg_requirement": "", "warnings": [{"functionality": "Disabling all kernel support for USB will cause problems for systems\nwith USB-based keyboards, mice, or printers. This configuration is\ninfeasible for systems which require USB devices, which is common."}], "conflicts": [], "requires": [], "policy_specific_content": {}, "platform": "grub2", "platforms": ["grub2"], "sce_metadata": {}, "inherited_platforms": [], "cpe_platform_names": ["grub2"], "inherited_cpe_platform_names": [], "bash_conditional": null, "fixes": {}, "title": "Disable Kernel Support for USB via Bootloader Configuration", "definition_location": "/aptdata/openscap/scap-security-guide/linux_os/guide/system/permissions/mounting/grub2_nousb_argument/rule.yml", "template": {"name": "grub2_bootloader_argument", "vars": {"arg_name": "nousb"}, "backends": {}}}