Guide to the Secure Configuration of OpenEmbedded
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure gnutls-utils is installed
Thegnutls-utilspackage can be installed with the following command:$ sudo dnf install gnutls-utils
Rule Medium Severity -
Ensure gpgcheck Enabled In Main dnf Configuration
The <code>gpgcheck</code> option controls whether RPM packages' signatures are always checked prior to installation. To configure dnf to check package signatures before installing them, ensure the ...Rule High Severity -
Modify the System Login Banner
To configure the system login banner edit <code>/etc/issue</code>. Replace the default text with a message compliant with the local site policy or a legal disclaimer. The DoD required text is ei...Rule Medium Severity -
Protect Accounts by Configuring PAM
PAM, or Pluggable Authentication Modules, is a system which implements modular authentication for Linux programs. PAM provides a flexible and configurable architecture for authentication, and it sh...Group -
Password Hashing algorithm for pam_unix.so
Specify the system default encryption algorithm for encrypting passwords. Defines the hashing algorithm to be used in pam_unix.so.Value -
Verify Owner on cron.monthly
To properly set the owner of/etc/cron.monthly, run the command:$ sudo chown root /etc/cron.monthly
Rule Medium Severity -
Limit Password Reuse: password-auth
Do not allow users to reuse recent passwords. This can be accomplished by using the <code>remember</code> option for the <code>pam_pwhistory</code> PAM module. <br> <br> On systems with n...Rule Medium Severity -
Ensure PAM Enforces Password Requirements - Minimum Different Categories
The pam_pwquality module's <code>minclass</code> parameter controls requirements for usage of different character classes, or types, of character that must exist in a password before it is consider...Rule Medium Severity -
Set PAM''s Password Hashing Algorithm
The PAM system service can be configured to only store encrypted representations of passwords. In "/etc/pam.d/system-auth", the <code>password</code> section of the file controls which PAM modules ...Rule Medium Severity -
Set Account Expiration Parameters
Accounts can be configured to be automatically disabled after a certain time period, meaning that they will require administrator interaction to become usable again. Expiration of accounts after in...Group -
Set Account Expiration Following Inactivity
To specify the number of days after a password expires (which signifies inactivity) until an account is permanently disabled, add or correct the following line in <code>/etc/default/useradd</code>:...Rule Medium Severity -
Set Password Maximum Age
To specify password maximum age for new accounts, edit the file <code>/etc/login.defs</code> and add or correct the following line: <pre>PASS_MAX_DAYS <xccdf-1.2:sub idref="xccdf_org.ssgproject.con...Rule Medium Severity -
Ensure There Are No Accounts With Blank or Null Passwords
Check the "/etc/shadow" file for blank passwords with the following command: <pre>$ sudo awk -F: '!$2 {print $1}' /etc/shadow</pre> If the command returns any results, this is a finding. Configure ...Rule High Severity -
Direct root Logins Not Allowed
To further limit access to the <code>root</code> account, administrators can disable root logins at the console by editing the <code>/etc/securetty</code> file. This file lists all devices the root...Rule Medium Severity -
Ensure the Logon Failure Delay is Set Correctly in login.defs
To ensure the logon failure delay controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>FAIL_DELAY</code> setting in <code>/etc/login.defs</code> to read as follows: ...Rule Medium Severity -
Limit the Number of Concurrent Login Sessions Allowed Per User
Limiting the number of allowed users and sessions per user can limit risks related to Denial of Service attacks. This addresses concurrent sessions for a single account and does not address concurr...Rule Low Severity -
Configure Polyinstantiation of /tmp Directories
To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use the following command: <pre>$ sudo mkdir --mode 000 ...Rule Low Severity -
Configure Polyinstantiation of /var/tmp Directories
To configure polyinstantiated /tmp directories, first create the parent directories which will hold the polyinstantiation child directories. Use the following command: <pre>$ sudo mkdir --mode 000 ...Rule Low Severity -
Set Interactive Session Timeout
Setting the <code>TMOUT</code> option in <code>/etc/profile</code> ensures that all user sessions will terminate based on inactivity. The value of TMOUT should be exported and read only. The <code>...Rule Medium 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 -
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 -
Disable Recovery Booting
OpenEmbedded systems support an "recovery boot" option that can be used to prevent services from being started. The <code>GRUB_DISABLE_RECOVERY</code> configuration option in <code>/etc/default/gru...Rule Medium Severity -
IOMMU configuration directive
On x86 architecture supporting VT-d, the IOMMU manages the access control policy between the hardware devices and some of the system critical units such as the memory. Configure the default Gru...Rule Unknown 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 -
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 -
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 -
Ensure debug-shell service is not enabled during boot
systemd's <code>debug-shell</code> service is intended to diagnose systemd related boot issues with various <code>systemctl</code> commands. Once enabled and following a system reboot, the root she...Rule Medium Severity -
Ensure Solid State Drives Do Not Contribute To Random-Number Entropy Pool
For each solid-state drive on the system, run:# echo 0 > /sys/block/DRIVE/queue/add_random
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 -
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 -
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 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 Logrotate Runs Periodically
The <code>logrotate</code> utility allows for the automatic rotation of log files. The frequency of rotation is specified in <code>/etc/logrotate.conf</code>, which triggers a cron task or a timer...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 syslog-ng is Installed
syslog-ng can be installed in replacement of rsyslog. Thesyslog-ng-corepackage can be installed with the following command:$ sudo dnf install syslog-ng-core
Rule Medium Severity -
Enable syslog-ng Service
The <code>syslog-ng</code> service (in replacement of rsyslog) provides syslog-style logging by default on Debian. The <code>syslog-ng</code> service can be enabled with the following command: <pr...Rule Medium Severity -
Enable rsyslog to Accept Messages via TCP, if Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. If the system needs to act as a central log server, add the following lines to <code>/etc/r...Rule Unknown Severity -
Enable rsyslog to Accept Messages via UDP, if Acting As Log Server
The <code>rsyslog</code> daemon should not accept remote messages unless the system acts as a log server. If the system needs to act as a central log server, add the following lines to <code>/etc/r...Rule Unknown Severity -
Verify Owner on cron.weekly
To properly set the owner of/etc/cron.weekly, run the command:$ sudo chown root /etc/cron.weekly
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 -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo dnf install firewalld
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 -
Inspect and Activate Default Rules
View the currently-enforced <code>iptables</code> rules by running the command: <pre>$ sudo iptables -nL --line-numbers</pre> The command is analogous for <code>ip6tables</code>. <br> <br> ...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 -
Configure Accepting Router Advertisements on All IPv6 Interfaces
To set the runtime status of the <code>net.ipv6.conf.all.accept_ra</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv6.conf.all.accept_ra=0</pre> To make sure that th...Rule Medium Severity -
Verify Owner on crontab
To properly set the owner of/etc/crontab, run the command:$ sudo chown root /etc/crontab
Rule Medium Severity
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