Guide to the Secure Configuration of Ubuntu 16.04
Rules, Groups, and Values defined within the XCCDF Benchmark
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Include Local Events in Audit Logs
To configure Audit daemon to include local events in Audit logs, set <code>local_events</code> to <code>yes</code> in <code>/etc/audit/auditd.conf<...Rule Medium Severity -
Resolve information before writing to audit logs
To configure Audit daemon to resolve all uid, gid, syscall, architecture, and socket address information before writing the events to disk, set <co...Rule Low Severity -
net.ipv6.conf.default.router_solicitations
Accept all router solicitations by default?Value -
net.ipv4.conf.default.rp_filter
Enables source route verificationValue -
Appropriate Action Must be Setup When the Internal Audit Event Queue is Full
The audit system should have an action setup in the event the internal event queue becomes full. To setup an overflow action edit <code>/etc/audit/...Rule Medium Severity -
Write Audit Logs to the Disk
To configure Audit daemon to write Audit logs to the disk, set <code>write_logs</code> to <code>yes</code> in <code>/etc/audit/auditd.conf</code>. ...Rule Medium Severity -
System Accounting with auditd
The <code>auditd</code> program can perform comprehensive monitoring of system activity. This section makes use of recommended configuration settin...Group -
AppArmor
Many security vulnerabilities result from bugs in trusted programs. A trusted program runs with privileges that attackers want to possess. The prog...Group -
AppArmor profiles mode
enforce - Set all AppArmor profiles to enforce mode
complain - Set all AppArmor profiles to complain modeValue -
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 -
Disable Recovery Booting
Ubuntu 16.04 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 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 -
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 -
net.ipv4.icmp_echo_ignore_broadcasts
Ignore all ICMP ECHO and TIMESTAMP requests sent to it via broadcast/multicastValue -
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 -
UEFI GRUB2 bootloader configuration
UEFI GRUB2 bootloader configurationGroup -
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 16.04...Group -
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 -
Enable checks on credential management
Enable this to turn on some debug checking for credential management. The additional code keeps track of the number of pointers from task_structs t...Rule Low Severity -
Disable kernel debugfs
<code>debugfs</code> is a virtual file system that kernel developers use to put debugging files into. Enable this option to be able to read and wri...Rule Low Severity -
Enable checks on linked list manipulation
Enable this to turn on extended checks in the linked-list walking routines. The configuration that was used to build kernel is available at <code>...Rule Low Severity -
Enable checks on notifier call chains
Enable this to turn on sanity checking for notifier call chains. This is most useful for kernel developers to make sure that modules properly unreg...Rule Low Severity -
Enable checks on scatter-gather (SG) table operations
Scatter-gather tables are mechanism used for high performance I/O on DMA devices. Enable this to turn on checks on scatter-gather tables. The conf...Rule Low Severity -
Configure low address space to protect from user allocation
This is the portion of low virtual memory which should be protected from userspace allocation. This configuration is available from kernel 3.14, bu...Rule Medium Severity -
Disable /dev/kmem virtual device support
Disable support for the /dev/kmem device. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To chec...Rule Low Severity -
Disable hibernation
Enable the suspend to disk (STD) functionality, which is usually called "hibernation" in user interfaces. STD checkpoints the system and powers it ...Rule Medium Severity -
Disable IA32 emulation
Disables support for legacy 32-bit programs under a 64-bit kernel. The configuration that was used to build kernel is available at <code>/boot/con...Rule Medium Severity -
Disable the IPv6 protocol
Disable support for IP version 6 (IPv6). The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check...Rule Medium Severity
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