Guide to the Secure Configuration of Ubuntu 18.04
Rules, Groups, and Values defined within the XCCDF Benchmark
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Sudo - passwd_timeout value
Defines the number of minutes before the <code>sudo</code> password prompt times out. Defining 0 means no timeout. The default timeout value is 5 m...Value -
Sudo - timestamp_timeout value
Defines the number of minutes that can elapse before <code>sudo</code> will ask for a passwd again. If set to a value less than 0 the user's time s...Value -
Sudo - umask value
Specify the sudo umask to use. The actual umask value that is used is the union of the user's umask and the sudo umask. The default sudo umask is 0...Value -
Ensure Privileged Escalated Commands Cannot Execute Other Commands - sudo NOEXEC
The sudo <code>NOEXEC</code> tag, when specified, prevents user executed commands from executing other commands, like a shell for example. This sho...Rule High Severity -
Ensure Only Users Logged In To Real tty Can Execute Sudo - sudo requiretty
The sudo <code>requiretty</code> tag, when specified, will only execute sudo commands from users logged in to a real tty. This should be enabled by...Rule Medium Severity -
Ensure Only Users Logged In To Real tty Can Execute Sudo - sudo use_pty
The sudo <code>use_pty</code> tag, when specified, will only execute sudo commands from users logged in to a real tty. This should be enabled by ma...Rule Medium Severity -
Ensure Sudo Logfile Exists - sudo logfile
A custom log sudo file can be configured with the 'logfile' tag. This rule configures a sudo custom logfile at the default location suggested by CI...Rule Low Severity -
Ensure Users Re-Authenticate for Privilege Escalation - sudo !authenticate
The sudo <code>!authenticate</code> option, when specified, allows a user to execute commands using sudo without having to authenticate. This shoul...Rule Medium Severity -
Ensure Users Re-Authenticate for Privilege Escalation - sudo NOPASSWD
The sudo <code>NOPASSWD</code> tag, when specified, allows a user to execute commands using sudo without having to authenticate. This should be dis...Rule Medium Severity -
Ensure Users Re-Authenticate for Privilege Escalation - sudo
The sudo <code>NOPASSWD</code> and <code>!authenticate</code> option, when specified, allows a user to execute commands using sudo without having t...Rule Medium Severity -
Only the VDSM User Can Use sudo NOPASSWD
The sudo <code>NOPASSWD</code> tag, when specified, allows a user to execute commands using sudo without having to authenticate. Only the <code>vds...Rule Medium Severity -
Explicit arguments in sudo specifications
All commands in the sudoers file must strictly specify the arguments allowed to be used for a given user. If the command is supposed to be executed...Rule Medium Severity -
Don't define allowed commands in sudoers by means of exclusion
Policies applied by sudo through the sudoers file should not involve negation. Each user specification in the <code>sudoers</code> file contains a...Rule Medium Severity -
Don't target root user in the sudoers file
The targeted users of a user specification should be, as much as possible, non privileged users (i.e.: non-root). User specifications have to expl...Rule Medium Severity -
System Tooling / Utilities
The following checks evaluate the system for recommended base packages -- both for installation and removal.Group -
Ensure gnutls-utils is installed
Thegnutls-utilspackage can be installed with the following command:$ apt-get install gnutls-utils
Rule Medium Severity -
Ensure nss-tools is installed
Thenss-toolspackage can be installed with the following command:$ apt-get install nss-tools
Rule Medium Severity -
Prevent Login to Accounts With Empty Password
If an account is configured for password authentication but does not have an assigned password, it may be possible to log into the account without ...Rule High Severity -
Action for auditd to take when disk errors
'The setting for disk_error_action in /etc/audit/auditd.conf, if multiple values are allowed write them separated by pipes as in "syslog|single|hal...Value -
Updating Software
The <code>apt_get</code> command line tool is used to install and update software packages. The system also provides a graphical software update to...Group -
Ensure Software Patches Installed
If the system has an apt repository available, run the following command to install updates: <pre>$ apt update && apt full-upgrade</pre> ...Rule Medium Severity -
Account and Access Control
In traditional Unix security, if an attacker gains shell access to a certain login account, they can perform any action or access any file to which...Group -
Authselect profile
Specify the authselect profile to selectValue -
Warning Banners for System Accesses
Each system should expose as little information about itself as possible. <br><br> System banners, which are typically displayed just before a logi...Group -
Login Banner Verbiage
Enter an appropriate login banner for your organization. Please note that new lines must be expressed by the '\n' character and special characters ...Value -
MotD Banner Verbiage
Enter an appropriate login banner for your organization. Please note that new lines must be expressed by the '\n' character and special characters ...Value -
Remote Login Banner Verbiage
Enter an appropriate login banner for your organization. Please note that new lines must be expressed by the '\n' character and special characters ...Value -
Implement a GUI Warning Banner
In the default graphical environment, users logging directly into the system are greeted with a login screen provided by the GNOME Display Manager ...Group -
Protect Accounts by Configuring PAM
PAM, or Pluggable Authentication Modules, is a system which implements modular authentication for Linux programs. PAM provides a flexible and confi...Group -
Password Hashing algorithm
Specify the system default encryption algorithm for encrypting passwords. Defines the value set as ENCRYPT_METHOD in /etc/login.defs.Value -
remember
The last n passwords for each user are saved in <code>/etc/security/opasswd</code> in order to force password change history and keep the user from...Value -
Action for auditd to take when disk is full
'The setting for disk_full_action in /etc/audit/auditd.conf, if multiple values are allowed write them separated by pipes as in "syslog|single|halt...Value -
Disallow Configuration to Bypass Password Requirements for Privilege Escalation
Verify the operating system is not configured to bypass password requirements for privilege escalation. Check the configuration of the "/etc/pam.d/...Rule Medium Severity -
Set Lockouts for Failed Password Attempts
The <code>pam_faillock</code> PAM module provides the capability to lock out user accounts after a number of failed login attempts. Its documentati...Group -
fail_deny
Number of failed login attempts before account lockoutValue -
faillock directory
The directory where the user files with the failure records are keptValue -
fail_interval
Interval for counting failed login attempts before account lockoutValue -
fail_unlock_time
Seconds before automatic unlocking or permanently locking after excessive failed loginsValue -
tally2_unlock_time
Seconds before automatic unlocking or permanently locking after excessive failed loginsValue -
faildelay_delay
Delay next login attempt after a failed loginValue -
pwhistory_remember
Prevent password re-use using password history lookupValue -
PAM pwhistory remember - control flag
'Specify the control flag required for password remember requirement. If multiple values are allowed write them separated by commas as in "required...Value -
tally2
Number of failed login attemptsValue -
Account Lockouts Must Be Logged
PAM faillock locks an account due to excessive password failures, this event must be logged.Rule Medium Severity -
Account Lockouts Must Persist
By setting a `dir` in the faillock configuration account lockouts will persist across reboots.Rule Medium Severity -
Account Lockouts Must Be Logged
PAM faillock locks an account due to excessive password failures, this event must be logged.Rule Medium Severity -
Set Password Quality Requirements
The default <code>pam_pwquality</code> PAM module provides strength checking for passwords. It performs a number of checks, such as making sure pas...Group -
Set Password Quality Requirements, if using pam_cracklib
The <code>pam_cracklib</code> PAM module can be configured to meet requirements for a variety of policies. <br><br> For example, to configure <code...Group -
Set Password Quality Requirements with pam_pwquality
The <code>pam_pwquality</code> PAM module can be configured to meet requirements for a variety of policies. <br><br> For example, to configure <cod...Group -
dcredit
Minimum number of digits in passwordValue
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