Guide to the Secure Configuration of Alibaba Cloud Linux 3
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure that User Home Directories are not Group-Writable or World-Readable
For each human user of the system, view the permissions of the user's home directory: <pre># ls -ld /home/<i>USER</i> </pre> Ensure that the directory is not group-writable and that it is n...Rule Medium Severity -
Configure L1 Terminal Fault mitigations
L1 Terminal Fault (L1TF) is a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Cache when the page table entry isn't present. Sele...Rule High Severity -
Configure the confidence in TPM for entropy
The TPM security chip that is available in most modern systems has a hardware RNG. It is also used to feed the entropy pool, but generally not credited entropy. Use <code>rng_core.default_quality<...Rule Low Severity -
Configure Speculative Store Bypass Mitigation
Certain CPUs are vulnerable to an exploit against a common wide industry wide performance optimization known as Speculative Store Bypass (SSB). In such cases, recent stores to the same memory loca...Rule Medium Severity -
Configure Low Address Space To Protect From User Allocation
This is the portion of low virtual memory which should be protected from userspace allocation. This configuration is available from kernel 3.14, but may be available if backported by distros. The ...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 -
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 -
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 Rsyslog Encrypts Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to support both local and remote logging. Couple this uti...Rule Medium Severity -
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 All Logs are Rotated by logrotate
Edit the file <code>/etc/logrotate.d/syslog</code>. Find the first line, which should look like this (wrapped for clarity): <pre>/var/log/messages /var/log/secure /var/log/maillog /var/log/spoole...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 -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo yum install firewalld
Rule Medium Severity -
Install libreswan Package
The libreswan package provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The <code>libreswan</code> package can be installed with the...Rule Medium Severity -
iptables and ip6tables
A host-based firewall called <code>netfilter</code> is included as part of the Linux kernel distributed with the system. It is activated by default. This firewall is controlled by the program <code...Group -
Strengthen the Default Ruleset
The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in the configuration files <code>iptables</code> and <code>ip6tables</code> in t...Group -
Disable Kernel Parameter for Accepting Source-Routed Packets on IPv6 Interfaces by Default
To set the runtime status of the <code>net.ipv6.conf.default.accept_source_route</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv6.conf.default.accept_source_route=...Rule Medium Severity -
Disable Accepting Packets Routed Between Local Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.accept_local</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.all.accept_local=0</pre> To make sure t...Rule Medium Severity -
Configure ARP filtering for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.arp_filter</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.all.arp_filter=<xccdf-1.2:sub idref="xccd...Rule Medium Severity -
Configure Sending and Accepting Shared Media Redirects for All IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.shared_media</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.all.shared_media=<xccdf-1.2:sub idref="...Rule Medium Severity
Node 2
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