Guide to the Secure Configuration of Amazon Linux 2023
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure that Root's Path Does Not Include World or Group-Writable Directories
For each element in root's path, run:# ls -ld DIRand ensure that write permissions are disabled for group and other.Rule Medium Severity -
Ensure that Root's Path Does Not Include Relative Paths or Null Directories
Ensure that none of the directories in root's path is equal to a single <code>.</code> character, or that it contains any instances that lead to relative path traversal, such as <code>..</code> or ...Rule Unknown 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 -
Sensible umask
Enter default user umaskValue -
Ensure the Default Bash Umask is Set Correctly
To ensure the default umask for users of the Bash shell is set properly, add or correct the <code>umask</code> setting in <code>/etc/bashrc</code> to read as follows: <pre>umask <xccdf-1.2:sub idre...Rule Medium Severity -
Ensure the Default Umask is Set Correctly in login.defs
To ensure the default umask controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>UMASK</code> setting in <code>/etc/login.defs</code> to read as follows: <pre>UMASK ...Rule Medium Severity -
Ensure the Default Umask is Set Correctly in /etc/profile
To ensure the default umask controlled by <code>/etc/profile</code> is set properly, add or correct the <code>umask</code> setting in <code>/etc/profile</code> to read as follows: <pre>umask <xccdf...Rule Medium Severity -
GRUB2 bootloader configuration
During the boot process, the boot loader is responsible for starting the execution of the kernel and passing options to it. The boot loader allows for the selection of different kernels - possibly ...Group -
Non-UEFI GRUB2 bootloader configuration
Non-UEFI GRUB2 bootloader configurationGroup -
Verify /boot/grub2/grub.cfg Group Ownership
The file <code>/boot/grub2/grub.cfg</code> should be group-owned by the <code>root</code> group to prevent destruction or modification of the file. To properly set the group owner of <code>/boot/g...Rule Medium Severity -
Verify /boot/grub2/user.cfg Group Ownership
The file <code>/boot/grub2/user.cfg</code> should be group-owned by the <code>root</code> group to prevent reading or modification of the file. To properly set the group owner of <code>/boot/grub2...Rule Medium Severity -
Verify /boot/grub2/grub.cfg User Ownership
The file <code>/boot/grub2/grub.cfg</code> should be owned by the <code>root</code> user to prevent destruction or modification of the file. To properly set the owner of <code>/boot/grub2/grub.cfg...Rule Medium Severity -
Verify /boot/grub2/user.cfg User Ownership
The file <code>/boot/grub2/user.cfg</code> should be owned by the <code>root</code> user to prevent reading or modification of the file. To properly set the owner of <code>/boot/grub2/user.cfg</co...Rule Medium Severity -
Verify /boot/grub2/grub.cfg Permissions
File permissions for <code>/boot/grub2/grub.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/grub2/grub.cfg</code>, run the command: <pre>$ sudo chmod 600 /boot/grub...Rule Medium Severity -
Verify /boot/grub2/user.cfg Permissions
File permissions for <code>/boot/grub2/user.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/grub2/user.cfg</code>, run the command: <pre>$ sudo chmod 600 /boot/grub...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 dnf install rsyslog
Rule Medium Severity -
Ensure rsyslog Default File Permissions Configured
rsyslog will create logfiles that do not already exist on the system. This settings controls what permissions will be applied to these newly created files.Rule Medium Severity -
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 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 Log Files Are Owned By Appropriate User
The 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> and t...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 -
systemd-journald
systemd-journald is a system service that collects and stores logging data. It creates and maintains structured, indexed journals based on logging information that is received from a variety of sou...Group -
Enable systemd-journald Service
The <code>systemd-journald</code> service is an essential component of systemd. The <code>systemd-journald</code> service can be enabled with the following command: <pre>$ sudo systemctl enable sy...Rule Medium Severity -
Ensure journald is configured to compress large log files
The journald system can compress large log files to avoid fill the system disk.Rule Medium Severity -
Ensure journald is configured to send logs to rsyslog
Data from journald may be stored in volatile memory or persisted locally. Utilities exist to accept remote export of journald logs.Rule Medium Severity -
Ensure journald is configured to write log files to persistent disk
The journald system may store log files in volatile memory or locally on disk. If the logs are only stored in volatile memory they will we lost upon reboot.Rule Medium Severity -
Disable systemd-journal-remote Socket
Journald supports the ability to receive messages from remote hosts, thus acting as a log server. Clients should not receive data from other hosts. NOTE: The same package, systemd-journal-remot...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 rsyslog Does Not Accept Remote Messages Unless Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. To ensure that it is not listening on the network, ensure any of the following lines are <i...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 -
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 -
Remote Log Server
Specify an URI or IP address of a remote host where the log messages will be sent and stored.Value -
Ensure Logs Sent To Remote Host
To configure rsyslog to send logs to a remote log server, open <code>/etc/rsyslog.conf</code> and read and understand the last section of the file, which describes the multiple directives necessary...Rule Medium Severity -
Network Configuration and Firewalls
Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses the security impact of decisions about networking wh...Group -
firewalld
The dynamic firewall daemon <code>firewalld</code> provides a dynamically managed firewall with support for network “zones” to assign a level of trust to a network and its associated connections an...Group -
Inspect and Activate Default firewalld Rules
Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffic within that network. <code>NetworkManager</code>...Group -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo dnf install firewalld
Rule Medium Severity -
Verify firewalld Enabled
Thefirewalldservice can be enabled with the following command:$ sudo systemctl enable firewalld.service
Rule Medium Severity -
net.ipv4.conf.default.log_martians
Disable so you don't Log Spoofed Packets, Source Routed Packets, Redirect PacketsValue -
net.ipv4.conf.default.rp_filter
Enables source route verificationValue -
Strengthen the Default Ruleset
The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in configuration files under the <code>/etc/firewalld/services</code> and <code>...Group -
Configure Firewalld to Restrict Loopback Traffic
Configure <code>firewalld</code> to restrict loopback traffic to the <code>lo</code> interface. The loopback traffic must be trusted by assigning the <code>lo</code> interface to the <code>firewal...Rule Medium Severity -
Configure Firewalld to Trust Loopback Traffic
Assign loopback interface to the <code>firewalld</code> <code>trusted</code> zone in order to explicitly allow the loopback traffic in the system. To configure <code>firewalld</code> to t...Rule Medium Severity -
Set Default firewalld Zone for Incoming Packets
To set the default zone to <code>drop</code> for the built-in default zone which processes incoming IPv4 and IPv6 packets, modify the following line in <code>/etc/firewalld/firewalld.conf</code> to...Rule Medium Severity -
IPv6
The system includes support for Internet Protocol version 6. A major and often-mentioned improvement over IPv4 is its enormous increase in the number of available addresses. Another important featu...Group -
Configure IPv6 Settings if Necessary
A major feature of IPv6 is the extent to which systems implementing it can automatically configure their networking devices using information from the network. From a security perspective, manually...Group -
net.ipv6.conf.all.accept_ra
Accept all router advertisements?Value -
net.ipv6.conf.all.accept_redirects
Toggle ICMP Redirect AcceptanceValue -
net.ipv6.conf.all.accept_source_route
Trackers could be using source-routed packets to generate traffic that seems to be intra-net, but actually was created outside and has been redirected.Value
Node 2
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