Guide to the Secure Configuration of UnionTech OS Server 20
Rules, Groups, and Values defined within the XCCDF Benchmark
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Limit Users' SSH Access
By default, the SSH configuration allows any user with an account to access the system. There are several options available to limit which users and group can access the system via SSH. It is recom...Rule Unknown Severity -
Ensure SSH LoginGraceTime is configured
The <code>LoginGraceTime</code> parameter to the SSH server specifies the time allowed for successful authentication to the SSH server. The longer the Grace period is the more open unauthenticated ...Rule Medium Severity -
Set LogLevel to INFO
The INFO parameter specifices that record login and logout activity will be logged. <br> The default SSH configuration sets the log level to INFO. The appropriate configuration is used if no value ...Rule Low Severity -
Set SSH Daemon LogLevel to VERBOSE
The <code>VERBOSE</code> parameter configures the SSH daemon to record login and logout activity. To specify the log level in SSH, add or correct the following line in <code>/etc/ssh/sshd_config<...Rule Medium Severity -
Set SSH authentication attempt limit
The <code>MaxAuthTries</code> parameter specifies the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures ar...Rule Medium Severity -
Set SSH MaxSessions limit
The <code>MaxSessions</code> parameter specifies the maximum number of open sessions permitted from a given connection. To set MaxSessions edit <code>/etc/ssh/sshd_config</code> as follows: <pre>Ma...Rule Medium Severity -
Enable Use of Privilege Separation
When enabled, SSH will create an unprivileged child process that has the privilege of the authenticated user. To enable privilege separation in SSH, add or correct the following line in the <code>/...Rule Medium Severity -
Verify and Correct File Permissions with RPM
The RPM package management system can check file access permissions of installed software packages, including many that are important to system security. Verify that the file permissions of system ...Rule High Severity -
Ensure /dev/shm is configured
The <code>/dev/shm</code> is a traditional shared memory concept. One program will create a memory portion, which other processes (if permitted) can access. If <code>/dev/shm</code> is not configur...Rule Low Severity -
Ensure PAM Displays Last Logon/Access Notification
To configure the system to notify users of last logon/access using <code>pam_lastlog</code>, add or correct the <code>pam_lastlog</code> settings in <code>/etc/pam.d/postlogin</code> to include <co...Rule Low Severity -
Restrict unprivileged access to the kernel syslog
Enforce restrictions on unprivileged users reading the kernel syslog via dmesg(8). The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the con...Rule Medium Severity -
Ensure Log Files Are Owned By Appropriate Group
The group-owner of all log files written by <code>rsyslog</code> should be <code>root</code>. These log files are determined by the second part of each Rule line in <code>/etc/rsyslog.conf</code> a...Rule Medium Severity -
Ensure All SGID Executables Are Authorized
The SGID (set group id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SGID files is determine if any were not install...Rule Medium Severity -
Verify Permissions on group File
To properly set the permissions of/etc/group, run the command:$ sudo chmod 0644 /etc/group
Rule Medium Severity -
Ensure logrotate is Installed
logrotate is installed by default. Thelogrotatepackage can be installed with the following command:$ sudo yum install logrotate
Rule Medium Severity -
Ensure Logrotate Runs Periodically
The <code>logrotate</code> utility allows for the automatic rotation of log files. The frequency of rotation is specified in <code>/etc/logrotate.conf</code>, which triggers a cron task or a timer...Rule Medium Severity -
Configure rsyslogd to Accept Remote Messages If Acting as a Log Server
By default, <code>rsyslog</code> does not listen over the network for log messages. If needed, modules can be enabled to allow the rsyslog daemon to receive messages from other systems and for the ...Group -
Ensure syslog-ng is Installed
syslog-ng can be installed in replacement of rsyslog. Thesyslog-ng-corepackage can be installed with the following command:$ sudo yum install syslog-ng-core
Rule Medium Severity -
Enable syslog-ng Service
The <code>syslog-ng</code> service (in replacement of rsyslog) provides syslog-style logging by default on Debian. The <code>syslog-ng</code> service can be enabled with the following command: <pr...Rule Medium Severity -
Enable rsyslog to Accept Messages via TCP, if Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. If the system needs to act as a central log server, add the following lines to <code>/etc/r...Rule Unknown Severity -
SSH is required to be installed
Specify if the Policy requires SSH to be installed. Used by SSH Rules to determine if SSH should be uninstalled or configured.<br> A value of 0 means that the policy doesn't care if OpenSSH server ...Value -
Install the OpenSSH Server Package
Theopenssh-serverpackage should be installed. Theopenssh-serverpackage can be installed with the following command:$ sudo yum install openssh-server
Rule Medium Severity -
Remove the OpenSSH Server Package
Theopenssh-serverpackage should be removed. Theopenssh-serverpackage can be removed with the following command:$ sudo yum erase openssh-server
Rule Medium Severity -
Verify File Hashes with RPM
Without cryptographic integrity protections, system executables and files can be altered by unauthorized users without detection. The RPM package management system can check the hashes of installed...Rule High Severity -
Configure BIND to use System Crypto Policy
Crypto Policies provide a centralized control over crypto algorithms usage of many packages. BIND is supported by crypto policy, but the BIND configuration may be set up to ignore it. To check tha...Rule High Severity -
Configure System Cryptography Policy
To configure the system cryptography policy to use ciphers only from the <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_system_crypto_policy" use="legacy"></xccdf-1.2:sub></code...Rule High Severity -
Disk Partitioning
To ensure separation and protection of data, there are top-level system directories which should be placed on their own physical partition or logical volume. The installer's default partitioning sc...Group -
GNOME Desktop Environment
GNOME is a graphical desktop environment bundled with many Linux distributions that allow users to easily interact with the operating system graphically rather than textually. The GNOME Graphical D...Group -
Configure GNOME Login Screen
In the default GNOME desktop, the login is displayed after system boot and can display user accounts, allow users to reboot the system, and allow users to login automatically and/or with a guest ac...Group -
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 should be disabled by making sure that the <code>!authe...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 only without arguments, pass "" as an argument in...Rule Medium Severity -
Ensure gnutls-utils is installed
Thegnutls-utilspackage can be installed with the following command:$ sudo yum install gnutls-utils
Rule Medium Severity -
Updating Software
The <code>yum</code> command line tool is used to install and update software packages. The system also provides a graphical software update tool in the <b>System</b> menu, in the <b>Administration...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 configurable architecture for authentication, and it sh...Group -
Set Account Expiration Parameters
Accounts can be configured to be automatically disabled after a certain time period, meaning that they will require administrator interaction to become usable again. Expiration of accounts after in...Group -
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 -
Set Password Maximum Age
To specify password maximum age for new accounts, edit the file <code>/etc/login.defs</code> and add or correct the following line: <pre>PASS_MAX_DAYS <xccdf-1.2:sub idref="xccdf_org.ssgproject.con...Rule Medium Severity -
Ensure There Are No Accounts With Blank or Null Passwords
Check the "/etc/shadow" file for blank passwords with the following command: <pre>$ sudo awk -F: '!$2 {print $1}' /etc/shadow</pre> If the command returns any results, this is a finding. Configure ...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 -
Ensure the Logon Failure Delay is Set Correctly in login.defs
To ensure the logon failure delay controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>FAIL_DELAY</code> setting in <code>/etc/login.defs</code> to read as follows: ...Rule Medium Severity -
Limit the Number of Concurrent Login Sessions Allowed Per User
Limiting the number of allowed users and sessions per user can limit risks related to Denial of Service attacks. This addresses concurrent sessions for a single account and does not address concurr...Rule Low 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 -
Disable Recovery Booting
UnionTech OS Server 20 systems support an "recovery boot" option that can be used to prevent services from being started. The <code>GRUB_DISABLE_RECOVERY</code> configuration option in <code>/etc/d...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 Cache when the page table entry isn't present. Sele...Rule High 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 disabled through kernel boot parameters. Ensure tha...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 -
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 -
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, but may be available if backported by distros. The ...Rule Medium Severity -
Configure Syslog
The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lack of authentication for received messages, and lac...Group -
Ensure rsyslog is Installed
Rsyslog is installed by default. Thersyslogpackage can be installed with the following command:$ sudo yum install rsyslog
Rule Medium Severity
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