Guide to the Secure Configuration of Red Hat Enterprise Linux CoreOS 4
Rules, Groups, and Values defined within the XCCDF Benchmark
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Configure the tmux Lock Command
To enable console screen locking in <code>tmux</code> terminal multiplexer, the <code>vlock</code> command must be configured to be used as a locking mechanism. Add the following line to <code>/etc...Rule Medium Severity -
Prevent user from disabling the screen lock
Thetmux
terminal multiplexer is used to implement automatic session locking. It should not be listed in/etc/shells
.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 -
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 authentication. Remove any instances of the <code>...Rule High 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 -
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 -
Set Password Expiration Parameters
The file <code>/etc/login.defs</code> controls several password-related settings. Programs such as <code>passwd</code>, <code>su</code>, and <code>login</code> consult <code>/etc/login.defs</code> ...Group -
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 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 -
Password Hashing algorithm
Specify the number of rounds for the system password encryption algorithm. Defines the value set in/etc/pam.d/system-auth
and/etc/pam.d/password-auth
Value -
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 -
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
Theroot
user should have a primary group of 0.Rule High Severity -
Ensure that System Accounts Do Not Run a Shell Upon Login
Some accounts are not associated with a human user of the system, and exist to perform some administrative functions. Should an attacker be able to log into these accounts, they should not be grant...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 -
Restrict Virtual Console Root Logins
To restrict root logins through the (deprecated) virtual console devices, ensure lines of this form do not appear in/etc/securetty
:vc/1 vc/2 vc/3 vc/4
Rule Medium Severity -
Ensure the audit Subsystem is Installed
The audit package should be installed.Rule Medium 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 -
Maximum login attempts delay
Maximum time in seconds between fail login attempts before re-prompting.Value -
Maximum concurrent login sessions
Maximum number of concurrent sessions by a userValue -
Account Inactivity Timeout (seconds)
In an interactive shell, the value is interpreted as the number of seconds to wait for input after issuing the primary prompt. Bash terminates after waiting for that number of seconds if input does...Value -
Interactive users initialization files
'A regular expression describing a list of file names for files that are sourced at login time for interactive users'Value -
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 Root's Path Does Not Include World or Group-Writable Directories
For each element in root's path, run:# ls -ld DIR
and 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 Bash Umask is Set Correctly
To ensure the default umask for users of the Bash shell is set properly, add or correct the <code>umask</code> setting in <code>/etc/bashrc</code> to read as follows: <pre>umask <xccdf-1.2:sub idre...Rule Medium Severity -
Ensure the Default C Shell Umask is Set Correctly
To ensure the default umask for users of the C shell is set properly, add or correct the <code>umask</code> setting in <code>/etc/csh.cshrc</code> to read as follows: <pre>umask <xccdf-1.2:sub idre...Rule Medium Severity -
Ensure the Default Umask is Set Correctly in login.defs
To ensure the default umask controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>UMASK</code> setting in <code>/etc/login.defs</code> to read as follows: <pre>UMASK ...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 -
System Audit Logs Must Have Mode 0640 or Less Permissive
Determine where the audit logs are stored with the following command: <pre>$ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log</pre> Configure the audit log to be p...Rule Medium Severity -
Record Execution Attempts to Run SELinux Privileged Commands
At a minimum, the audit system should collect the execution of SELinux privileged commands for all users and root.Group -
Ensure auditd Collects Unauthorized Access Attempts to Files (unsuccessful)
At a minimum the audit system should collect unauthorized file accesses for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read au...Rule Medium Severity -
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 -
Auditd priority for flushing data to disk
The setting for flush in /etc/audit/auditd.confValue
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