Guide to the Secure Configuration of Ubuntu 20.04
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure AppArmor is installed
AppArmor provide Mandatory Access Controls.Rule Medium Severity -
Enforce all AppArmor Profiles
AppArmor profiles define what resources applications are able to access. To set all profiles to enforce mode run the following command: <pre>$ sudo...Rule Medium Severity -
All AppArmor Profiles are in enforce or complain mode
AppArmor profiles define what resources applications are able to access. To set all profiles to either <code>enforce</code> or <code>complain</code...Rule Medium Severity -
Ensure AppArmor is Active and Configured
Verify that the Apparmor tool is configured to control whitelisted applications and user home directory access control.<br><br> The <code>apparmor...Rule Medium Severity -
authlogin_radius SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
net.ipv6.conf.all.accept_source_route
Trackers could be using source-routed packets to generate traffic that seems to be intra-net, but actually was created outside and has been redirec...Value -
UEFI GRUB2 bootloader configuration
UEFI GRUB2 bootloader configurationGroup -
net.ipv6.conf.all.autoconf
Enable auto configuration on IPv6 interfacesValue -
net.ipv6.conf.all.forwarding
Toggle IPv6 ForwardingValue -
net.ipv6.conf.all.max_addresses
Maximum number of autoconfigured IPv6 addressesValue -
systemd-journald
systemd-journald is a system service that collects and stores logging data. It creates and maintains structured, indexed journals based on logging ...Group -
net.ipv6.conf.all.router_solicitations
Accept all router solicitations?Value -
net.ipv6.conf.default.accept_ra_defrtr
Accept default router in router advertisements?Value -
Ensure AppArmor is enabled in the bootloader configuration
Configure AppArmor to be enabled at boot time and verify that it has not been overwritten by the bootloader boot parameters. Note: This recommenda...Rule Medium Severity -
GRUB2 bootloader configuration
During the boot process, the boot loader is responsible for starting the execution of the kernel and passing options to it. The boot loader allows ...Group -
L1TF vulnerability mitigation
Defines the L1TF vulneratility mitigations to employ.Value -
MDS vulnerability mitigation
Defines the MDS vulneratility mitigation to employ.Value -
Confidence level on Hardware Random Number Generator
Defines the level of trust on the hardware random number generators available in the system and the percentage of entropy to credit.Value -
Spec Store Bypass Mitigation
This controls how the Speculative Store Bypass (SSB) vulnerability is mitigated.Value -
net.ipv6.conf.default.accept_ra_pinfo
Accept prefix information in router advertisements?Value -
Disable Recovery Booting
Ubuntu 20.04 systems support an "recovery boot" option that can be used to prevent services from being started. The <code>GRUB_DISABLE_RECOVERY</co...Rule Medium Severity -
IOMMU configuration directive
On x86 architecture supporting VT-d, the IOMMU manages the access control policy between the hardware devices and some of the system critical u...Rule Unknown Severity -
Configure L1 Terminal Fault mitigations
L1 Terminal Fault (L1TF) is a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Ca...Rule High Severity -
Force kernel panic on uncorrected MCEs
A Machine Check Exception is an error generated by the CPU itdetects an error in itself, memory or I/O devices. These errors may be corrected and g...Rule Medium Severity -
Ensure SMAP is not disabled during boot
The SMAP is used to prevent the supervisor mode from unintentionally reading/writing into memory pages in the user space, it is enabled by default ...Rule Medium Severity -
Ensure SMEP is not disabled during boot
The SMEP is used to prevent the supervisor mode from executing user space code, it is enabled by default since Linux kernel 3.0. But it could be di...Rule Medium Severity -
Configure the confidence in TPM for entropy
The TPM security chip that is available in most modern systems has a hardware RNG. It is also used to feed the entropy pool, but generally not cred...Rule Low Severity -
Disable merging of slabs with similar size
The kernel may merge similar slabs together to reduce overhead and increase cache hotness of objects. Disabling merging of slabs keeps the slabs se...Rule Medium Severity -
Configure Speculative Store Bypass Mitigation
Certain CPUs are vulnerable to an exploit against a common wide industry wide performance optimization known as Speculative Store Bypass (SSB). In...Rule Medium Severity -
Enforce Spectre v2 mitigation
Spectre V2 is an indirect branch poisoning attack that can lead to data leakage. An exploit for Spectre V2 tricks the indirect branch predictor int...Rule High Severity -
Ensure debug-shell service is not enabled during boot
systemd's <code>debug-shell</code> service is intended to diagnose systemd related boot issues with various <code>systemctl</code> commands. Once e...Rule Medium Severity -
Non-UEFI GRUB2 bootloader configuration
Non-UEFI GRUB2 bootloader configurationGroup -
Verify /boot/grub/grub.cfg User Ownership
The file <code>/boot/grub/grub.cfg</code> should be owned by the <code>root</code> user to prevent destruction or modification of the file. To pro...Rule Medium Severity -
Verify /boot/grub/grub.cfg Permissions
File permissions for <code>/boot/grub/grub.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/grub/grub.cfg</code>, r...Rule Medium Severity -
Set Boot Loader Password in grub2
The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings. <br><br> Since plaintext passw...Rule High Severity -
Set the UEFI Boot Loader Password
The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings. <br><br> Since plaintext passw...Rule High Severity -
zIPL bootloader configuration
During the boot process, the bootloader is responsible for starting the execution of the kernel and passing options to it. The default Ubuntu 20.04...Group -
Enable Auditing to Start Prior to the Audit Daemon in zIPL
To ensure all processes can be audited, even those which start prior to the audit daemon, check that all boot entries in <code>/boot/loader/entries...Rule Medium Severity -
Extend Audit Backlog Limit for the Audit Daemon in zIPL
To improve the kernel capacity to queue all log events, even those which start prior to the audit daemon, check that all boot entries in <code>/boo...Rule Medium Severity -
Protect Random-Number Entropy Pool
The I/O operations of the Linux kernel block layer due to their inherently unpredictable execution times have been traditionally considered as a re...Group -
Ensure Solid State Drives Do Not Contribute To Random-Number Entropy Pool
For each solid-state drive on the system, run:# echo 0 > /sys/block/DRIVE/queue/add_random
Rule Medium Severity -
Kernel Configuration
Contains rules that check the kernel configuration that was used to build it.Group -
Hash function for kernel module signing
The hash function to use when signing modules during kernel build process.Value -
Key and certificate for kernel module signing
The private key and certificate to use when signing modules during kernel build process. On systems where the OpenSSL ENGINE_pkcs11 is functional —...Value -
Kernel panic timeout
The time, in seconds, to wait until a reboot occurs. If the value is <code>0</code> the system never reboots. If the value is less than <code>0</co...Value -
Do not allow ACPI methods to be inserted/replaced at run time
This debug facility allows ACPI AML methods to be inserted and/or replaced without rebooting the system. This configuration is available from kerne...Rule Low Severity -
Disable kernel support for MISC binaries
Enabling <code>CONFIG_BINFMT_MISC</code> makes it possible to plug wrapper-driven binary formats into the kernel. This is specially useful for prog...Rule Medium Severity -
Enable support for BUG()
Disabling this option eliminates support for BUG and WARN, reducing the size of your kernel image and potentially quietly ignoring numerous fatal c...Rule Medium Severity -
Disable compatibility with brk()
Enabling compatiliby with <code>brk()</code> allows legacy binaries to run (i.e. those linked against libc5). But this compatibility comes at the c...Rule Medium Severity -
Disable the 32-bit vDSO
Certain buggy versions of glibc (2.3.3) will crash if they are presented with a 32-bit vDSO that is not mapped at the address indicated in its segm...Rule Low Severity
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