Guide to the Secure Configuration of Ubuntu 20.04
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure PAM Enforces Password Requirements - Authentication Retry Prompts Permitted Per-Session
To configure the number of retry prompts that are permitted per-session: Edit the <code>pam_pwquality.so</code> statement in <code>/etc/pam.d/common-password</code> to show <code>retry=<xccdf-1...Rule Medium Severity -
Ensure PAM Enforces Password Requirements - Minimum Uppercase Characters
The pam_pwquality module's <code>ucredit=</code> parameter controls requirements for usage of uppercase letters in a password. When set to a negative number, any password will be required to contai...Rule Medium Severity -
Set Password Hashing Algorithm
The system's default algorithm for storing password hashes in/etc/shadowis SHA-512. This can be configured in several locations.Group -
Set Password Hashing Algorithm in /etc/login.defs
In <code>/etc/login.defs</code>, add or update the following line to ensure the system will use <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_password_hashing_algorithm" use="legacy"...Rule Medium Severity -
Protect Physical Console Access
It is impossible to fully protect a system from an attacker with physical access, so securing the space in which the system is located should be considered a necessary step. However, there are some...Group -
Disable Ctrl-Alt-Del Burst Action
By default, <code>SystemD</code> will reboot the system if the <code>Ctrl-Alt-Del</code> key sequence is pressed Ctrl-Alt-Delete more than 7 times in 2 seconds. <br> <br> To configure the s...Rule High Severity -
Configure Screen Locking
When a user must temporarily leave an account logged-in, screen locking should be employed to prevent passersby from abusing the account. User education and training is particularly important for s...Group -
Configure Console Screen Locking
A console screen locking mechanism is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of th...Group -
Check that vlock is installed to allow session locking
The Ubuntu 20.04 operating system must have vlock installed to allow for session locking. The <code>vlock</code> package can be installed with the following command: <pre> $ apt-get install vlock...Rule Medium Severity -
Hardware Tokens for Authentication
The use of hardware tokens such as smart cards for system login provides stronger, two-factor authentication than using a username and password. In Red Hat Enterprise Linux servers and workstation...Group -
Install the opensc Package For Multifactor Authentication
Theopensc-pkcs11package can be installed with the following command:$ apt-get install opensc-pkcs11
Rule Medium Severity -
Install Smart Card Packages For Multifactor Authentication
Configure the operating system to implement multifactor authentication by installing the required package with the following command: The <code>libpam-pkcs11</code> package can be installed with t...Rule Medium Severity -
Configure Smart Card Certificate Authority Validation
Configure the operating system to do certificate status checking for PKI authentication. Modify all of the <code>cert_policy</code> lines in <code>/etc/pam_pkcs11/pam_pkcs11.conf</code> to include ...Rule Medium Severity -
Configure Smart Card Local Cache of Revocation Data
Configure the operating system for PKI-based authentication to use local revocation data when unable to access the network to obtain it remotely. Modify all of the <code>cert_policy</code> lines in...Rule Medium Severity -
Verify that 'use_mappers' is set to 'pwent' in PAM
The operating system must map the authenticated identity to the user or group account for PKI-based authentication. Verify that <code>use_mappers</code> is set to <code>pwent</code> in <code>/etc/...Rule Low Severity -
Protect Accounts by Restricting Password-Based Login
Conventionally, Unix shell accounts are accessed by providing a username and password to a login program, which tests these values for correctness using the <code>/etc/passwd</code> and <code>/etc/...Group -
Ensure All Accounts on the System Have Unique User IDs
Change user IDs (UIDs), or delete accounts, so each has a unique name.Rule Medium Severity -
Ensure All Groups on the System Have Unique Group ID
Change the group name or delete groups, so each has a unique id.Rule Medium Severity -
Ensure All Groups on the System Have Unique Group Names
Change the group name or delete groups, so each has a unique name.Rule Medium Severity -
number of days after a password expires until the account is permanently disabled
The number of days to wait after a password expires, until the account will be permanently disabled.Value -
Assign Expiration Date to Temporary Accounts
Temporary accounts are established as part of normal account activation procedures when there is a need for short-term accounts. In the event temporary accounts are required, configure the system t...Rule Medium Severity -
Ensure All Accounts on the System Have Unique Names
Ensure accounts on the system have unique names. To ensure all accounts have unique names, run the following command: <pre>$ sudo getent passwd | awk -F: '{ print $1}' | uniq -d</pre> If a usernam...Rule Medium Severity -
Use Centralized and Automated Authentication
Implement an automated system for managing user accounts that minimizes the risk of errors, either intentional or deliberate. This system should integrate with an existing enterprise user managemen...Rule Medium Severity -
Ensure shadow Group is Empty
The shadow group allows system programs which require access the ability to read the /etc/shadow file. No users should be assigned to the shadow group.Rule Medium Severity -
Policy Requires Immediate Change of Temporary Passwords
Temporary passwords for Ubuntu 20.04 operating system logons must require an immediate change to a permanent password. Verify that a policy exists that ensures when a user is created, it is creati...Rule Medium Severity -
maximum password age
Maximum age of password in daysValue -
minimum password age
Minimum age of password in daysValue -
minimum password length
Minimum number of characters in passwordValue -
warning days before password expires
The number of days' warning given before a password expires.Value -
Set Password Minimum Age
To specify password minimum age for new accounts, edit the file <code>/etc/login.defs</code> and add or correct the following line: <pre>PASS_MIN_DAYS <xccdf-1.2:sub idref="xccdf_org.ssgproject.con...Rule Medium Severity -
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 Existing Passwords Maximum Age
Configure non-compliant accounts to enforce a <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_accounts_maximum_age_login_defs" use="legacy"></xccdf-1.2:sub>-day maximum password lifeti...Rule Medium Severity -
Offload audit Logs to External Media
The operating system must have a crontab script running weekly to offload audit events of standalone systems.Rule Medium Severity -
Set Existing Passwords Minimum Age
Configure non-compliant accounts to enforce a 24 hours/1 day minimum password lifetime by running the following command:$ sudo chage -m 1 USERRule 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 -
Verify All Account Password Hashes are Shadowed with SHA512
Verify the operating system requires the shadow password suite configuration be set to encrypt interactive user passwords using a strong cryptographic hash. Check that the interactive user account ...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 -
Ensure sudo group has only necessary members
Developers and implementers can increase the assurance in security functions by employing well-defined security policy models; structured, disciplined, and rigorous hardware and software developmen...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 -
Ensure no duplicate UIDs exist
Although the useradd program will not let you create a duplicate User ID (UID), it is possible for an administrator to manually edit the /etc/passwd file and change the UID field. Users must be ass...Rule Medium Severity -
All Interactive User Home Directories Must Have mode 0750 Or Less Permissive
Change the mode of interactive users home directories to <code>0750</code>. To change the mode of interactive users home directory, use the following command: <pre>$ sudo chmod 0750 /home/<i>USER</...Rule Medium Severity -
Verify No .forward Files Exist
The.forwardfile specifies an email address to forward the user's mail to.Rule Medium Severity -
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 -
Group Name Used by pam_wheel Group Parameter
pam_wheel module has a parameter called group, which controls which groups can access the su command. This variable holds the valid value for the parameter.Value -
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 -
Ensure Authentication Required for Single User Mode
Single user mode is used for recovery when the system detects an issue during boot or by manual selection from the bootloader.Rule Medium Severity -
Direct root Logins Are Not Allowed
Configure the operating system to prevent direct logins to therootaccount by performing the following operations:$ sudo passwd -l root
Rule Medium Severity
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