Centro Criptológico Nacional (CCN) - STIC for Red Hat Enterprise Linux 9 - Basic
Rules and Groups employed by this XCCDF Profile
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Disable Kernel Parameter for Accepting ICMP Redirects by Default on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.default.accept_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.accept_redirects=0</pre...Rule Medium Severity -
Disable Kernel Parameter for Accepting Source-Routed Packets on IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.accept_source_route=...Rule Medium Severity -
Enable Kernel Paremeter to Log Martian Packets on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.log_martians</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.log_martians=1</pre> To mak...Rule Unknown Severity -
Enable Kernel Parameter to Use Reverse Path Filtering on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.rp_filter</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.rp_filter=1</pre> To make sure...Rule Medium Severity -
Configure Kernel Parameter for Accepting Secure Redirects By Default
To set the runtime status of the <code>net.ipv4.conf.default.secure_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0</pre...Rule Medium Severity -
Enable Kernel Parameter to Ignore ICMP Broadcast Echo Requests on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.icmp_echo_ignore_broadcasts</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1</pre> To...Rule Medium Severity -
Enable Kernel Parameter to Ignore Bogus ICMP Error Responses on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.icmp_ignore_bogus_error_responses</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_response...Rule Unknown Severity -
Enable Kernel Parameter to Use TCP Syncookies on Network Interfaces
To set the runtime status of the <code>net.ipv4.tcp_syncookies</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.tcp_syncookies=1</pre> To make sure that the settin...Rule Medium Severity -
Network Parameters for Hosts Only
If the system is not going to be used as a router, then setting certain kernel parameters ensure that the host will not perform routing of network traffic.Group -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.all.send_redirects=0</pre> To make su...Rule Medium Severity -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.send_redirects=0</pre> To...Rule Medium Severity -
Disable Kernel Parameter for IP Forwarding on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.ip_forward</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.ip_forward=0</pre> To make sure that the setting is per...Rule Medium Severity -
nftables
<code>If firewalld or iptables are being used in your environment, please follow the guidance in their respective section and pass-over the guidance in this section.</code><br><br> nftables is a su...Group -
Verify nftables Service is Disabled
nftables is a subsystem of the Linux kernel providing filtering and classification of network packets/datagrams/frames and is the successor to iptables. The <code>nftables</code> service can be dis...Rule Medium Severity -
File Permissions and Masks
Traditional Unix security relies heavily on file and directory permissions to prevent unauthorized users from reading or modifying files to which they should not have access. <br> <br> ...Group -
Restrict Programs from Dangerous Execution Patterns
The recommendations in this section are designed to ensure that the system's features to protect against potentially dangerous program execution are activated. These protections are applied at the ...Group -
Disable Core Dumps
A core dump file is the memory image of an executable program when it was terminated by the operating system due to errant behavior. In most cases, only software developers legitimately need to acc...Group -
Disable Core Dumps for SUID programs
To set the runtime status of the <code>fs.suid_dumpable</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.suid_dumpable=0</pre> To make sure that the setting is persisten...Rule Medium Severity -
Services
The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat Enterprise Linux 9 installs on a system and disable softwar...Group -
SSH Server
The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between two systems, as well as server authentication, throu...Group -
Configure OpenSSH Server if Necessary
If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_config</code>. The following recommendations can be app...Group -
Set SSH Client Alive Count Max
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The option <code>ClientAliveInterval</code> configures time...Rule Medium Severity -
Set SSH Client Alive Interval
SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automatically logged out. <br> <br> To se...Rule Medium Severity -
Enable SSH Warning Banner
To enable the warning banner and ensure it is consistent across the system, add or correct the following line in <code>/etc/ssh/sshd_config.d/00-complianceascode-hardening.conf</code>: <pre>Banne...Rule Medium Severity -
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 -
USBGuard daemon
The USBGuard daemon enforces the USB device authorization policy for all USB devices.Group -
Install usbguard Package
Theusbguardpackage can be installed with the following command:$ sudo dnf install usbguard
Rule Medium Severity -
Enable the USBGuard Service
The USBGuard service should be enabled. Theusbguardservice can be enabled with the following command:$ sudo systemctl enable usbguard.service
Rule Medium Severity -
Generate USBGuard Policy
By default USBGuard when enabled prevents access to all USB devices and this lead to inaccessible system if they use USB mouse/keyboard. To prevent this scenario, the initial policy configuration m...Rule Medium Severity
Node 2
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