Disable Kernel Support for USB via Bootloader Configuration

An XCCDF Rule

Description

All USB support can be disabled by adding the nousb argument to the kernel's boot loader configuration. To do so, append "nousb" to the kernel line in /etc/default/grub as shown:

kernel /vmlinuz-VERSION ro vga=ext root=/dev/VolGroup00/LogVol00 rhgb quiet nousb

warning alert: Functionality Warning

Disabling all kernel support for USB will cause problems for systems with USB-based keyboards, mice, or printers. This configuration is infeasible for systems which require USB devices, which is common.

Rationale

Disabling the USB subsystem within the Linux kernel at system boot will protect against potentially malicious USB devices, although it is only practical in specialized systems.

ID: xccdf_org.ssgproject.content_rule_grub2_nousb_argument
Severity: Unknown
References: 12 16

APO13.01 DSS01.04 DSS05.03 DSS05.04 DSS05.05 DSS05.07 DSS06.03

CCI-001250

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)

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

SR 1.1 SR 1.13 SR 1.2 SR 1.4 SR 1.5 SR 1.9 SR 2.1 SR 2.6

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

CM-6(a) MP-7

PR.AC-3 PR.AC-6

CCE-26548-8
Updated: about 1 year ago

# Remediation is applicable only in certain platforms
if rpm --quiet -q grub2-common; then

# Correct the form of default kernel command line in /etc/default/grub
if ! grep -q '^GRUB_CMDLINE_LINUX=".*nousb.*"' /etc/default/grub;
then  # Edit configuration setting
  # Append 'nousb' argument to /etc/default/grub (if not present yet)
  sed -i "s/\(GRUB_CMDLINE_LINUX=\)\"\(.*\)\"/\1\"\2 nousb\"/" /etc/default/grub
  # Edit runtime setting
  # Correct the form of kernel command line for each installed kernel in the bootloader
  /sbin/grubby --update-kernel=ALL --args="nousb"
fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Disable Kernel Support for USB via Bootloader Configuration

Description

Rationale

Remediation - Shell Script