CIS Amazon Linux 2023 Benchmark for Level 1 - Server
Rules and Groups employed by this XCCDF Profile
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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 -
Verify Group Who Owns /etc/cron.allow file
If <code>/etc/cron.allow</code> exists, it must be group-owned by <code>root</code>. To properly set the group owner of <code>/etc/cron.allow</code>, run the command: <pre>$ sudo chgrp root /etc/c...Rule Medium Severity -
Verify User Who Owns /etc/at.allow file
If <code>/etc/at.allow</code> exists, it must be owned by <code>root</code>. To properly set the owner of <code>/etc/at.allow</code>, run the command: <pre>$ sudo chown root /etc/at.allow </pre> ...Rule Medium Severity -
Verify User Who Owns /etc/cron.allow file
If <code>/etc/cron.allow</code> exists, it must be owned by <code>root</code>. To properly set the owner of <code>/etc/cron.allow</code>, run the command: <pre>$ sudo chown root /etc/cron.allow </...Rule Medium Severity -
Verify Permissions on /etc/at.allow file
If <code>/etc/at.allow</code> exists, it must have permissions <code>0640</code> or more restrictive. To properly set the permissions of <code>/etc/at.allow</code>, run the command: <pre>$ sudo c...Rule Medium Severity -
Verify Permissions on /etc/cron.allow file
If <code>/etc/cron.allow</code> exists, it must have permissions <code>0640</code> or more restrictive. To properly set the permissions of <code>/etc/cron.allow</code>, run the command: <pre>$ su...Rule Medium Severity -
DHCP
The Dynamic Host Configuration Protocol (DHCP) allows systems to request and obtain an IP address and other configuration parameters from a server. <br> <br> This guide recommends configuring...Group -
Disable DHCP Server
The DHCP server <code>dhcpd</code> is not installed or activated by default. If the software was installed and activated, but the system does not need to act as a DHCP server, it should be disabled...Group -
Uninstall DHCP Server Package
If the system does not need to act as a DHCP server, the dhcp package can be uninstalled. The <code>dhcp</code> package can be removed with the following command: <pre> $ sudo dnf remove dhcp</pre...Rule Medium Severity -
DNS Server
Most organizations have an operational need to run at least one nameserver. However, there are many common attacks involving DNS server software, and this server software should be disabled on any ...Group -
Uninstall dnsmasq Package
dnsmasq is a lightweight tool that provides DNS caching, DNS forwarding and DHCP (Dynamic Host Configuration Protocol) services. <br> The <code>dnsmasq</code> package can be removed with the follow...Rule Low Severity -
Disable DNS Server
DNS software should be disabled on any systems which does not need to be a nameserver. Note that the BIND DNS server software is not installed on Amazon Linux 2023 by default. The remainder of this...Group -
Uninstall bind Package
Thenamed
service is provided by thebind
package. Thebind
package can be removed with the following command:$ sudo dnf remove bind
Rule Low Severity -
FTP Server
FTP is a common method for allowing remote access to files. Like telnet, the FTP protocol is unencrypted, which means that passwords and other data transmitted during the session can be captured an...Group -
Remove ftp Package
FTP (File Transfer Protocol) is a traditional and widely used standard tool for transferring files between a server and clients over a network, especially where no authentication is necessary (perm...Rule Low Severity -
Disable vsftpd if Possible
To minimize attack surface, disable vsftpd if at all possible.Group -
Uninstall vsftpd Package
Thevsftpd
package can be removed with the following command:$ sudo dnf remove vsftpd
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> <br> <ul> <li>The HTTP port is commo...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 dnf remove httpd
Rule Unknown Severity -
Disable NGINX if Possible
If NGINX was installed and activated, but the system does not need to act as a web server, then it should be removed from the system.Group -
Uninstall nginx Package
Thenginx
package can be removed with the following command:$ sudo dnf remove nginx
Rule Unknown Severity -
IMAP and POP3 Server
Dovecot provides IMAP and POP3 services. It is not installed by default. The project page at <a href="http://www.dovecot.org">http://www.dovecot.org</a> contains more detailed information abou...Group -
Disable Cyrus IMAP
If the system does not need to operate as an IMAP or POP3 server, the Cyrus IMAP software should be removed.Group -
Uninstall cyrus-imapd Package
Thecyrus-imapd
package can be removed with the following command:$ sudo dnf remove cyrus-imapd
Rule Unknown Severity -
Disable Dovecot
If the system does not need to operate as an IMAP or POP3 server, the dovecot software should be disabled and removed.Group -
Uninstall dovecot Package
Thedovecot
package can be removed with the following command:$ sudo dnf remove dovecot
Rule Unknown Severity -
LDAP
LDAP is a popular directory service, that is, a standardized way of looking up information from a central database. Amazon Linux 2023 includes software that enables a system to act as both an LDAP ...Group -
Configure OpenLDAP Clients
This section provides information on which security settings are important to configure in OpenLDAP clients by manually editing the appropriate configuration files. Amazon Linux 2023 provides an a...Group -
Ensure LDAP client is not installed
The Lightweight Directory Access Protocol (LDAP) is a service that provides a method for looking up information from a central database. The <code>openldap-clients</code> package can be removed wit...Rule Low Severity -
Mail Server Software
Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious targets of network attack. Ensure that systems are not r...Group -
Ensure Mail Transfer Agent is not Listening on any non-loopback Address
Mail Transfer Agents (MTA), such as sendmail and Postfix, are used to listen for incoming mail and transfer the messages to the appropriate user or mail server. If the system is not intended to be ...Rule Medium Severity -
Configure SMTP For Mail Clients
This section discusses settings for Postfix in a submission-only e-mail configuration.Group -
Disable Postfix Network Listening
Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the following <code>inet_interfaces</code> line appears: <pre>inet_interfaces = <xccdf-1.2:sub idref="xccdf_org.ssgproject.conten...Rule Medium Severity -
NFS and RPC
The Network File System is a popular distributed filesystem for the Unix environment, and is very widely deployed. This section discusses the circumstances under which it is possible to disable NF...Group -
Disable All NFS Services if Possible
If there is not a reason for the system to operate as either an NFS client or an NFS server, follow all instructions in this section to disable subsystems required by NFS.Group -
Disable Services Used Only by NFS
If NFS is not needed, disable the NFS client daemons nfslock, rpcgssd, and rpcidmapd. <br> <br> All of these daemons run with elevated privileges, and many listen for network connections. I...Group -
Disable rpcbind Service
The rpcbind utility maps RPC services to the ports on which they listen. RPC processes notify rpcbind when they start, registering the ports they are listening on and the RPC program numbers they e...Rule Low Severity -
Configure NFS Clients
The steps in this section are appropriate for systems which operate as NFS clients.Group -
Disable NFS Server Daemons
There is no need to run the NFS server daemons <code>nfs</code> and <code>rpcsvcgssd</code> except on a small number of properly secured systems designated as NFS servers. Ensure that these daemons...Group -
Disable Network File System (nfs)
The Network File System (NFS) service allows remote hosts to mount and interact with shared filesystems on the local system. If the local system is not designated as a NFS server then this 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 unpredictably on unmanaged systems. Central time protocols can...Group -
A remote time server for Chrony is configured
<code>Chrony</code> is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. M...Rule Medium Severity -
Ensure that chronyd is running under chrony user account
chrony is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More informati...Rule Medium Severity -
Obsolete Services
This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or severely limiting the service has been the best a...Group -
Uninstall rsync Package
The rsyncd service can be used to synchronize files between systems over network links. The <code>rsync</code> package can be removed with the following command: <pre> $ sudo dnf remove rsync</pre>...Rule Medium Severity
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