Guide to the Secure Configuration of Anolis OS 8
Rules, Groups, and Values defined within the XCCDF Benchmark
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Verify Permissions on /var/log/syslog File
To properly set the permissions of/var/log/syslog, run the command:$ sudo chmod 0640 /var/log/syslog
Rule Medium Severity -
Verify that System Executable Have Root Ownership
<pre>/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin</pre> All these directories should be owned by the <code>root</code> user. If any directory <i>DIR</i> in these directories is foun...Rule Medium 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 -
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 -
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 -
Verify Integrity with AIDE
AIDE conducts integrity checks by comparing information about files with previously-gathered information. Ideally, the AIDE database is created immediately after initial system configuration, and t...Group -
Install AIDE
Theaidepackage can be installed with the following command:$ sudo yum install aide
Rule Medium Severity -
Configure Periodic Execution of AIDE
At a minimum, AIDE should be configured to run a weekly scan. To implement a daily execution of AIDE at 4:05am using cron, add the following line to <code>/etc/crontab</code>: <pre>05 4 * * * root ...Rule Medium Severity -
Configure Libreswan to use System Crypto Policy
Crypto Policies provide a centralized control over crypto algorithms usage of many packages. Libreswan is supported by system crypto policy, but the Libreswan configuration may be set up to ignore ...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 -
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 -
Disable XDMCP in GDM
XDMCP is an unencrypted protocol, and therefore, presents a security risk, see e.g. <a href="https://help.gnome.org/admin/gdm/stable/security.html.en_GB#xdmcpsecurity">XDMCP Gnome docs</a>. To dis...Rule High 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 -
Ensure gpgcheck Enabled In Main yum Configuration
The <code>gpgcheck</code> option controls whether RPM packages' signatures are always checked prior to installation. To configure yum to check package signatures before installing them, ensure the ...Rule High Severity -
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 login prompt, give out information about the s...Group -
Modify the System Login Banner
To configure the system login banner edit <code>/etc/issue</code>. Replace the default text with a message compliant with the local site policy or a legal disclaimer. The DoD required text is ei...Rule Medium Severity -
Verify permissions on System Login Banner
To properly set the permissions of/etc/issue, run the command:$ sudo chmod 0644 /etc/issue
Rule Medium Severity -
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 -
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 -
Password Hashing algorithm for pam_unix.so
Specify the system default encryption algorithm for encrypting passwords. Defines the hashing algorithm to be used in pam_unix.so.Value -
Limit Password Reuse: password-auth
Do not allow users to reuse recent passwords. This can be accomplished by using the <code>remember</code> option for the <code>pam_pwhistory</code> PAM module. <br> <br> On systems with n...Rule Medium Severity -
Ensure PAM Enforces Password Requirements - Minimum Different Categories
The pam_pwquality module's <code>minclass</code> parameter controls requirements for usage of different character classes, or types, of character that must exist in a password before it is consider...Rule Medium Severity -
Set PAM''s Password Hashing Algorithm
The PAM system service can be configured to only store encrypted representations of passwords. In "/etc/pam.d/system-auth", the <code>password</code> section of the file controls which PAM modules ...Rule Medium Severity -
Set Account Expiration Following Inactivity
To specify the number of days after a password expires (which signifies inactivity) until an account is permanently disabled, add or correct the following line in <code>/etc/default/useradd</code>:...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 -
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 -
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 -
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 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 -
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 -
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 -
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 Proper Configuration of Log Files
The file <code>/etc/rsyslog.conf</code> controls where log message are written. These are controlled by lines called <i>rules</i>, which consist of a <i>selector</i> and an <i>action</i>. These rul...Group -
Ensure Rsyslog Encrypts Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to support both local and remote logging. Couple this uti...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 System Log Files Have Correct Permissions
The file permissions for all log files written by <code>rsyslog</code> should be set to 640, or more restrictive. These log files are determined by the second part of each Rule line in <code>/etc/r...Rule Medium Severity -
Ensure All Logs are Rotated by logrotate
Edit the file <code>/etc/logrotate.d/syslog</code>. Find the first line, which should look like this (wrapped for clarity): <pre>/var/log/messages /var/log/secure /var/log/maillog /var/log/spoole...Group -
Rsyslog Logs Sent To Remote Host
If system logs are to be useful in detecting malicious activities, it is necessary to send logs to a remote server. An intruder who has compromised the root account on a system may delete the log e...Group -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo yum install firewalld
Rule Medium Severity -
Install libreswan Package
The libreswan package provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The <code>libreswan</code> package can be installed with the...Rule Medium Severity -
iptables and ip6tables
A host-based firewall called <code>netfilter</code> is included as part of the Linux kernel distributed with the system. It is activated by default. This firewall is controlled by the program <code...Group -
Install iptables Package
Theiptablespackage can be installed with the following command:$ sudo yum install iptables
Rule Medium Severity -
Strengthen the Default Ruleset
The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in the configuration files <code>iptables</code> and <code>ip6tables</code> in t...Group -
Configure Accepting Router Advertisements on All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.accept_ra</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv6.conf.all.accept_ra=0</pre> To make sure that th...Rule Medium Severity -
Disable Accepting ICMP Redirects for All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.accept_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv6.conf.all.accept_redirects=0</pre> To mak...Rule Medium Severity
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