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Guide to the Secure Configuration of Amazon Linux 2023

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Ensure No World-Writable Files Exist

    It is generally a good idea to remove global (other) write access to a file when it is discovered. However, check with documentation for specific applications before making changes. Also, monitor f...
    Rule Medium Severity
  • Ensure All Files Are Owned by a Group

    If any file is not group-owned by a group present in /etc/group, the cause of the lack of group-ownership must be investigated. Following this, those files should be deleted or assigned to an appro...
    Rule Medium Severity
  • Ensure All Files Are Owned by a User

    If any files are not owned by a user, then the cause of their lack of ownership should be investigated. Following this, the files should be deleted or assigned to an appropriate user. Locate the m...
    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>group</code>, and <code>gshadow</code> files must be ...
    Group
  • Verify Group Who Owns Backup group File

    To properly set the group owner of /etc/group-, run the command:
    $ sudo chgrp root /etc/group-
    Rule Medium Severity
  • Verify that audit tools are owned by group root

    The Amazon Linux 2023 operating system audit tools must have the proper ownership configured to protected against unauthorized access. Verify it by running the following command: <pre>$ stat -c "%...
    Rule Medium Severity
  • Verify that audit tools are owned by root

    The Amazon Linux 2023 operating system audit tools must have the proper ownership configured to protected against unauthorized access. Verify it by running the following command: <pre>$ stat -c "%...
    Rule Medium Severity
  • Verify that audit tools Have Mode 0755 or less

    The Amazon Linux 2023 operating system audit tools must have the proper permissions configured to protected against unauthorized access. Verify it by running the following command: <pre>$ stat -c ...
    Rule Medium Severity
  • Restrict Dynamic Mounting and Unmounting of Filesystems

    Linux includes a number of facilities for the automated addition and removal of filesystems on a running system. These facilities may be necessary in many environments, but this capability also ca...
    Group
  • Disable Mounting of cramfs

    To configure the system to prevent the <code>cramfs</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/cramfs.conf</code>: <pre>install cramfs /bin/fa...
    Rule Low Severity
  • Disable Mounting of freevxfs

    To configure the system to prevent the <code>freevxfs</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/freevxfs.conf</code>: <pre>install freevxfs /...
    Rule Low Severity
  • Disable Mounting of hfs

    To configure the system to prevent the <code>hfs</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/hfs.conf</code>: <pre>install hfs /bin/false</pre>...
    Rule Low Severity
  • Disable Mounting of hfsplus

    To configure the system to prevent the <code>hfsplus</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/hfsplus.conf</code>: <pre>install hfsplus /bin...
    Rule Low Severity
  • Disable Mounting of jffs2

    To configure the system to prevent the <code>jffs2</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/jffs2.conf</code>: <pre>install jffs2 /bin/false...
    Rule Low Severity
  • Disable Mounting of squashfs

    To configure the system to prevent the <code>squashfs</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/squashfs.conf</code>: <pre>install squashfs /...
    Rule Low Severity
  • Disable Mounting of udf

    To configure the system to prevent the <code>udf</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/udf.conf</code>: <pre>install udf /bin/false</pre>...
    Rule Low Severity
  • Disable Modprobe Loading of USB Storage Driver

    To prevent USB storage devices from being used, configure the kernel module loading system to prevent automatic loading of the USB storage driver. To configure the system to prevent the <code>usb-...
    Rule Medium Severity
  • Restrict Partition Mount Options

    System partitions can be mounted with certain options that limit what files on those partitions can do. These options are set in the <code>/etc/fstab</code> configuration file, and can be used to m...
    Group
  • Add nodev Option to /dev/shm

    The <code>nodev</code> mount option can be used to prevent creation of device files in <code>/dev/shm</code>. Legitimate character and block devices should not exist within temporary directories li...
    Rule Medium Severity
  • Add noexec Option to /dev/shm

    The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/dev/shm</code>. It can be dangerous to allow the execution of binaries from world-writable tem...
    Rule Medium Severity
  • Add nosuid Option to /dev/shm

    The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/dev/shm</code>. The SUID and SGID permissions should not be required in these world-writable dire...
    Rule Medium Severity
  • Add nodev Option to /home

    The <code>nodev</code> mount option can be used to prevent device files from being created in <code>/home</code>. Legitimate character and block devices should exist only in the <code>/dev</code> d...
    Rule Unknown Severity
  • Add nosuid Option to /home

    The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/home</code>. The SUID and SGID permissions should not be required in these user data directories. ...
    Rule Medium Severity
  • Add nodev Option to /tmp

    The <code>nodev</code> mount option can be used to prevent device files from being created in <code>/tmp</code>. Legitimate character and block devices should not exist within temporary directories...
    Rule Medium Severity
  • Install libselinux Package

    The libselinux package can be installed with the following command:
    $ sudo dnf install libselinux
    Rule High Severity
  • Restrict usage of ptrace to descendant processes

    To set the runtime status of the <code>kernel.yama.ptrace_scope</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.yama.ptrace_scope=1</pre> To make sure that the sett...
    Rule Medium 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, only software developers legitimately need to acc...
    Group
  • Disable core dump backtraces

    The <code>ProcessSizeMax</code> option in <code>[Coredump]</code> section of <code>/etc/systemd/coredump.conf</code> specifies the maximum size in bytes of a core which will be processed. Core dump...
    Rule Medium Severity
  • Disable storing core dump

    The Storage option in [Coredump] sectionof /etc/systemd/coredump.conf can be set to none to disable storing core dumps permanently.
    Rule Medium Severity
  • Enable ExecShield

    ExecShield describes kernel features that provide protection against exploitation of memory corruption errors such as buffer overflows. These features include random placement of the stack and othe...
    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.randomize_va_space=2</pre> To make sure that the se...
    Rule Medium Severity
  • SELinux

    SELinux is a feature of the Linux kernel which can be used to guard against misconfigured or compromised programs. SELinux enforces the idea that programs should be limited in what files they can a...
    Group
  • SELinux policy

    Type of policy in use. Possible values are:
    targeted - Only targeted network daemons are protected.
    strict - Full SELinux protection.
    mls - Multiple levels of security
    Value
  • SELinux state

    enforcing - SELinux security policy is enforced.
    permissive - SELinux prints warnings instead of enforcing.
    disabled - SELinux is fully disabled.
    Value
  • Ensure No Daemons are Unconfined by SELinux

    Daemons for which the SELinux policy does not contain rules will inherit the context of the parent process. Because daemons are launched during startup and descend from the <code>init</code> proces...
    Rule Medium Severity
  • Ensure SELinux is Not Disabled

    The SELinux state should be set to <code>enforcing</code> or <code>permissive</code> at system boot time. In the file <code>/etc/selinux/config</code>, add or correct the following line to configur...
    Rule High Severity
  • Configure SELinux Policy

    The SELinux <code>targeted</code> policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To configure the system to use this policy, add or correct ...
    Rule Medium Severity
  • Ensure SELinux State is Enforcing

    The SELinux state should be set to <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_selinux_state" use="legacy"></xccdf-1.2:sub></code> at system boot time. In the file <code>/et...
    Rule High Severity
  • Services

    The best protection against vulnerable software is running less software. This section describes how to review the software which Amazon Linux 2023 installs on a system and disable software which i...
    Group
  • Avahi Server

    The Avahi daemon implements the DNS Service Discovery and Multicast DNS protocols, which provide service and host discovery on a network. It allows a system to automatically identify resources on t...
    Group
  • Disable Avahi Server if Possible

    Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Disabling it can reduce the system's vulnerability to such attacks.
    Group
  • Uninstall avahi Server Package

    If the system does not need to have an Avahi server which implements the DNS Service Discovery and Multicast DNS protocols, the avahi-autoipd and avahi packages can be uninstalled.
    Rule Medium Severity
  • 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 necessary maintenance tasks, while at may or may no...
    Group
  • 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 maintenance tasks, such as notifying root of system acti...
    Rule Medium Severity
  • Verify Group Who Owns cron.d

    To properly set the group owner of /etc/cron.d, run the command:
    $ sudo chgrp root /etc/cron.d
    Rule Medium Severity
  • Restrict at and cron to Authorized Users if Necessary

    The <code>/etc/cron.allow</code> and <code>/etc/at.allow</code> files contain lists of users who are allowed to use <code>cron</code> and at to delay execution of processes. If these files exist an...
    Group
  • Ensure that /etc/at.deny does not exist

    The file /etc/at.deny should not exist. Use /etc/at.allow instead.
    Rule Medium Severity
  • Ensure that /etc/cron.allow exists

    The file /etc/cron.allow should exist and should be used instead of /etc/cron.deny.
    Rule Medium Severity
  • Ensure that /etc/cron.deny does not exist

    The file /etc/cron.deny should not exist. Use /etc/cron.allow instead.
    Rule Medium Severity
  • Verify Group Who Owns /etc/at.allow file

    If <code>/etc/at.allow</code> exists, it must be group-owned by <code>root</code>. To properly set the group owner of <code>/etc/at.allow</code>, run the command: <pre>$ sudo chgrp root /etc/at.al...
    Rule Medium Severity

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