Guide to the Secure Configuration of Ubuntu 16.04
Rules, Groups, and Values defined within the XCCDF Benchmark
-
Set Password Minimum Length in login.defs
To specify password length requirements for new accounts, edit the file <code>/etc/login.defs</code> and add or correct the following line: <pre>PASS_MIN_LEN <xccdf-1.2:sub idref="xccdf_org.ssgproj...Rule Medium Severity -
Set Password Warning Age
To specify how many days prior to password expiration that a warning will be issued to users, edit the file <code>/etc/login.defs</code> and add or correct the following line: <pre>PASS_WARN_AGE <...Rule Medium Severity -
Verify Proper Storage and Existence of Password Hashes
By default, password hashes for local accounts are stored in the second field (colon-separated) in <code>/etc/shadow</code>. This file should be readable only by processes running with root credent...Group -
Verify All Account Password Hashes are Shadowed
If any password hashes are stored in <code>/etc/passwd</code> (in the second field, instead of an <code>x</code> or <code>*</code>), the cause of this misconfiguration should be investigated. The a...Rule Medium Severity -
Ensure all users last password change date is in the past
All users should have a password change date in the past.Rule Medium Severity -
All GIDs referenced in /etc/passwd must be defined in /etc/group
Add a group to the system for each GID referenced without a corresponding group.Rule Low Severity -
Secure Session Configuration Files for Login Accounts
When a user logs into a Unix account, the system configures the user's session by reading a number of files. Many of these files are located in the user's home directory, and may have weak permissi...Group -
Verify No netrc Files Exist
The <code>.netrc</code> files contain login information used to auto-login into FTP servers and reside in the user's home directory. These files may contain unencrypted passwords to remote FTP serv...Rule Medium Severity -
Restrict Root Logins
Direct root logins should be allowed only for emergency use. In normal situations, the administrator should access the system via a unique unprivileged account, and then use <code>su</code> or <cod...Group -
Verify Only Root Has UID 0
If any account other than root has a UID of 0, this misconfiguration should be investigated and the accounts other than root should be removed or have their UID changed. <br> If the account is asso...Rule High Severity -
Verify Root Has A Primary GID 0
Therootuser should have a primary group of 0.Rule High Severity -
Direct root Logins Not Allowed
To further limit access to the <code>root</code> account, administrators can disable root logins at the console by editing the <code>/etc/securetty</code> file. This file lists all devices the root...Rule Medium Severity -
Restrict Serial Port Root Logins
To restrict root logins on serial ports, ensure lines of this form do not appear in/etc/securetty:ttyS0 ttyS1
Rule Medium Severity -
Configure Polyinstantiation of /tmp Directories
To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use the following command: <pre>$ sudo mkdir --mode 000 ...Rule Low Severity -
Configure Polyinstantiation of /var/tmp Directories
To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use the following command: <pre>$ sudo mkdir --mode 000 ...Rule Low Severity -
Ensure that User Home Directories are not Group-Writable or World-Readable
For each human user of the system, view the permissions of the user's home directory: <pre># ls -ld /home/<i>USER</i> </pre> Ensure that the directory is not group-writable and that it is n...Rule Medium Severity -
Ensure that No Dangerous Directories Exist in Root's Path
The active path of the root account can be obtained by starting a new root shell and running: <pre># echo $PATH</pre> This will produce a colon-separated list of directories in the path. <br> ...Group -
Ensure that Root's Path Does Not Include World or Group-Writable Directories
For each element in root's path, run:# ls -ld DIRand ensure that write permissions are disabled for group and other.Rule Medium Severity -
Ensure that Root's Path Does Not Include Relative Paths or Null Directories
Ensure that none of the directories in root's path is equal to a single <code>.</code> character, or that it contains any instances that lead to relative path traversal, such as <code>..</code> or ...Rule Unknown Severity -
Ensure that Users Have Sensible Umask Values
The umask setting controls the default permissions for the creation of new files. With a default <code>umask</code> setting of 077, files and directories created by users will not be readable by an...Group -
Sensible umask
Enter default user umaskValue -
Ensure the Default Umask is Set Correctly in /etc/profile
To ensure the default umask controlled by <code>/etc/profile</code> is set properly, add or correct the <code>umask</code> setting in <code>/etc/profile</code> to read as follows: <pre>umask <xccdf...Rule Medium Severity -
System Accounting with auditd
The audit service provides substantial capabilities for recording system activities. By default, the service audits about SELinux AVC denials and certain types of security-relevant events such as s...Group -
Ensure the audit Subsystem is Installed
The audit package should be installed.Rule Medium Severity -
net.ipv4.conf.default.shared_media
Controls whether the system can send(router) or accept(host) RFC1620 shared media redirects. <code>shared_media</code> for the interface will be enabled if at least one of conf/{all,interface}/shar...Value -
Disable Support for IPv6 Unless Needed
Despite configuration that suggests support for IPv6 has been disabled, link-local IPv6 address auto-configuration occurs even when only an IPv4 address is assigned. The only way to effectively pre...Group -
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 for the selection of different kernels - possibly ...Group -
L1TF vulnerability mitigation
Defines the L1TF vulneratility mitigations 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 -
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 such cases, recent stores to the same memory loca...Rule Medium Severity -
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/auditd.conf</code>. Set <code>overflow_action</cod...Rule Medium Severity -
Write Audit Logs to the Disk
To configure Audit daemon to write Audit logs to the disk, setwrite_logstoyesin/etc/audit/auditd.conf. This is the default setting.Rule Medium 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 generate a check log entry, if an error cannot be c...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 since Linux kernel 3.7. But it could be disabled t...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 credited entropy. Use <code>rng_core.default_quality<...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 separate and reduces the risk of kernel heap overflo...Rule Medium 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 enabled and following a system reboot, the root she...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 reliable source to contribute to random-number entro...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 — a PKCS#11 URI as defined by RFC7512 In the latter...Value -
Kernel panic timeout
The time, in seconds, to wait until a reboot occurs. If the value is0the system never reboots. If the value is less than0the system reboots immediately.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 kernel 3.0. The configuration that was used to build k...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 programs that need an interpreter to run like Java, Py...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 conditions. You should only consider disabling this...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 cost of not being able to randomize the heap placem...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 segment table. Setting <code>CONFIG_COMPAT_VDSO</code>...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 to any given cred struct, and checks to see that th...Rule Low Severity
Node 2
The content of the drawer really is up to you. It could have form fields, definition lists, text lists, labels, charts, progress bars, etc. Spacing recommendation is 24px margins. You can put tabs in here, and can also make the drawer scrollable.