Standard System Security Profile for SUSE Linux Enterprise 15
Rules and Groups employed by this XCCDF Profile
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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 ...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_fo...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 t...Group -
Verify Permissions on Important Files and Directories
Permissions for many files on a system must be set restrictively to ensure sensitive information is properly protected. This section discusses impo...Group -
Verify that local System.map file (if exists) is readable only by root
Files containing sensitive informations should be protected by restrictive permissions. Most of the time, there is no need that these files need ...Rule Unknown Severity -
Enable Kernel Parameter to Enforce DAC on Hardlinks
To set the runtime status of the <code>fs.protected_hardlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protecte...Rule Medium Severity -
Enable Kernel Parameter to Enforce DAC on Symlinks
To set the runtime status of the <code>fs.protected_symlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protected...Rule Medium Severity -
Verify Permissions on Files with Local Account Information and Credentials
The default restrictive permissions for files which act as important security databases such as <code>passwd</code>, <code>shadow</code>, <code>gro...Group -
Verify Group Who Owns group File
To properly set the group owner of/etc/group
, run the command:$ sudo chgrp root /etc/group
Rule Medium Severity -
Verify Group Who Owns gshadow File
To properly set the group owner of/etc/gshadow
, run the command:$ sudo chgrp root /etc/gshadow
Rule Medium Severity -
Verify Group Who Owns passwd File
To properly set the group owner of/etc/passwd
, run the command:$ sudo chgrp root /etc/passwd
Rule Medium Severity -
Verify Group Who Owns shadow File
To properly set the group owner of/etc/shadow
, run the command:$ sudo chgrp shadow /etc/shadow
Rule Medium Severity -
Verify User Who Owns group File
To properly set the owner of/etc/group
, run the command:$ sudo chown root /etc/group
Rule Medium Severity -
Verify User Who Owns gshadow File
To properly set the owner of/etc/gshadow
, run the command:$ sudo chown root /etc/gshadow
Rule Medium Severity -
Verify User Who Owns passwd File
To properly set the owner of/etc/passwd
, run the command:$ sudo chown root /etc/passwd
Rule Medium Severity -
Verify User Who Owns shadow File
To properly set the owner of/etc/shadow
, run the command:$ sudo chown root /etc/shadow
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 -
Verify Permissions on gshadow File
To properly set the permissions of/etc/gshadow
, run the command:$ sudo chmod 0000 /etc/gshadow
Rule Medium Severity -
Verify Permissions on passwd File
To properly set the permissions of/etc/passwd
, run the command:$ sudo chmod 0644 /etc/passwd
Rule Medium Severity -
Verify Permissions on shadow File
To properly set the permissions of/etc/shadow
, run the command:$ sudo chmod 0640 /etc/shadow
Rule Medium Severity -
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 ar...Group -
Restrict Access to Kernel Message Buffer
To set the runtime status of the <code>kernel.dmesg_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.dmesg...Rule Low Severity -
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,...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=...Rule Medium Severity -
Enable ExecShield
ExecShield describes kernel features that provide protection against exploitation of memory corruption errors such as buffer overflows. These featu...Group -
Enable Randomized Layout of Virtual Address Space
To set the runtime status of the <code>kernel.randomize_va_space</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.r...Rule Medium Severity -
Services
The best protection against vulnerable software is running less software. This section describes how to review the software which SUSE Linux Enterp...Group -
Cron and At Daemons
The cron and at services are used to allow commands to be executed at a later time. The cron service is required by almost all systems to perform n...Group -
Install the cron service
The Cron service should be installed.Rule Medium Severity -
Enable cron Service
The <code>crond</code> service is used to execute commands at preconfigured times. It is required by almost all systems to perform necessary mainte...Rule Medium Severity -
Deprecated services
Some deprecated software services impact the overall system security due to their behavior (leak of confidentiality in network exchange, usage as u...Group -
Uninstall the inet-based telnet server
The inet-based telnet daemon should be uninstalled.Rule High Severity -
Uninstall the nis package
The support for Yellowpages should not be installed unless it is required.Rule Low Severity -
Uninstall the ntpdate package
ntpdate is a historical ntp synchronization client for unixes. It sould be uninstalled.Rule Low Severity -
Uninstall the ssl compliant telnet server
Thetelnet
daemon, even with ssl support, should be uninstalled.Rule High Severity -
Uninstall the telnet server
The telnet daemon should be uninstalled.Rule High Severity -
Web Server
The web server is responsible for providing access to content via the HTTP protocol. Web servers represent a significant security risk because: <br...Group -
Disable Apache if Possible
If Apache was installed and activated, but the system does not need to act as a web server, then it should be disabled and removed from the system.Group -
Uninstall httpd Package
Thehttpd
package can be removed with the following command:$ sudo zypper remove httpd
Rule Unknown Severity -
Disable httpd Service
Thehttpd
service can be disabled with the following command:$ sudo systemctl mask --now httpd.service
Rule Unknown Severity -
Network Time Protocol
The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictabl...Group -
Install the ntp service
The ntpd service should be installed.Rule High Severity -
Enable the NTP Daemon
Thentp
service can be enabled with the following command:$ sudo systemctl enable ntp.service
Rule High Severity -
SSH Server
The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between tw...Group -
Install the OpenSSH Client and Server Package
The <code>openssh</code> package should be installed. The <code>openssh</code> package can be installed with the following command: <pre> $ sudo zy...Rule Medium Severity -
Enable the OpenSSH Service
The SSH server service, sshd, is commonly needed. The <code>sshd</code> service can be enabled with the following command: <pre>$ sudo systemctl e...Rule Medium Severity -
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_confi...Group -
Set SSH Client Alive Count Max to zero
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The optio...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 automat...Rule Medium Severity -
Allow Only SSH Protocol 2
Only SSH protocol version 2 connections should be permitted. The default setting in <code>/etc/ssh/sshd_config</code> is correct, and can be verifi...Rule High Severity
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