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Guide to the Secure Configuration of Debian 10

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Enable seccomp to safely compute untrusted bytecode

    This kernel feature is useful for number crunching applications that may need to compute untrusted bytecode during their execution. By using pipes or other transports made available to the process ...
    Rule Medium Severity
  • Enable use of Berkeley Packet Filter with seccomp

    Enable tasks to build secure computing environments defined in terms of Berkeley Packet Filter programs which implement task-defined system call filtering polices. The configuration that was used ...
    Rule Medium Severity
  • Enable different security models

    This allows you to choose different security modules to be configured into your kernel. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check th...
    Rule Medium Severity
  • Disable mutable hooks

    Ensure kernel structures associated with LSMs are always mapped as read-only after system boot. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To ...
    Rule Medium Severity
  • Enable Yama support

    This enables support for LSM module Yama, which extends DAC support with additional system-wide security settings beyond regular Linux discretionary access controls. The module will limit the use o...
    Rule Medium Severity
  • Enable SLUB debugging support

    SLUB has extensive debug support features and this allows the allocator validation checking to be enabled. The configuration that was used to build kernel is available at <code>/boot/config-*</cod...
    Rule Medium Severity
  • Enable TCP/IP syncookie support

    Normal TCP/IP networking is open to an attack known as SYN flooding. It is denial-of-service attack that prevents legitimate remote users from being able to connect to your computer during an ongoi...
    Rule Medium Severity
  • Unmap kernel when running in userspace (aka KAISER)

    Speculation attacks against some high-performance processors can be used to bypass MMU permission checks and leak kernel data to userspace. This can be defended against by unmapping the kernel when...
    Rule Medium Severity
  • Disable x86 vsyscall emulation

    Disabling it is roughly equivalent to booting with vsyscall=none, except that it will also disable the helpful warning if a program tries to use a vsyscall. With this option set to N, offending pro...
    Rule Low Severity
  • Kernel GCC plugin configuration

    Contains rules that check the configuration of GCC plugins used by the compiler
    Group
  • 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. The rsyslog package can be installed with the following command:
     $ apt-get install rsyslog
    Rule Medium Severity
  • Enable rsyslog Service

    The <code>rsyslog</code> service provides syslog-style logging by default on Debian 10. The <code>rsyslog</code> service can be enabled with the following command: <pre>$ sudo systemctl enable rsy...
    Rule Medium Severity
  • Configure Logwatch on the Central Log Server

    Is this system the central log server? If so, edit the file /etc/logwatch/conf/logwatch.conf as shown below.
    Group
  • 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
  • User who owns log files

    Specify user owner of all logfiles specified in /etc/rsyslog.conf.
    Value
  • Ensure Rsyslog Authenticates 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 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
  • 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
  • net.ipv6.conf.all.router_solicitations

    Accept all router solicitations?
    Value
  • 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 User

    The owner of all log files written by <code>rsyslog</code> should be <code>adm</code>. These log files are determined by the second part of each Rule line in <code>/etc/rsyslog.conf</code> and ty...
    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 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 is Installed

    logrotate is installed by default. The logrotate package can be installed with the following command:
     $ apt-get install logrotate
    Rule Medium Severity
  • 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
  • net.ipv4.conf.default.secure_redirects

    Enable to prevent hijacking of routing path by only allowing redirects from gateways known in routing table. Disable to refuse acceptance of secure ICMP redirected packages by default.
    Value
  • 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
  • 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
  • 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
  • IPSec Support

    Support for Internet Protocol Security (IPsec) is provided with Libreswan.
    Group
  • 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> If the fi...
    Group
  • Verify ip6tables Enabled if Using IPv6

    The ip6tables service can be enabled with the following command:
    $ sudo systemctl enable ip6tables.service
    Rule Medium Severity
  • Verify iptables Enabled

    The iptables service can be enabled with the following command:
    $ sudo systemctl enable iptables.service
    Rule Medium Severity
  • Set Default ip6tables Policy for Incoming Packets

    To set the default policy to DROP (instead of ACCEPT) for the built-in INPUT chain which processes incoming packets, add or correct the following line in <code>/etc/sysconfig/ip6tables</code>: <pre...
    Rule Medium Severity
  • 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
  • Set Default iptables Policy for Incoming Packets

    To set the default policy to DROP (instead of ACCEPT) for the built-in INPUT chain which processes incoming packets, add or correct the following line in <code>/etc/sysconfig/iptables</code>: <pre>...
    Rule Medium Severity
  • net.ipv6.conf.default.accept_ra_defrtr

    Accept default router in router advertisements?
    Value
  • Set Default iptables Policy for Forwarded Packets

    To set the default policy to DROP (instead of ACCEPT) for the built-in FORWARD chain which processes packets that will be forwarded from one interface to another, add or correct the following line ...
    Rule Medium Severity
  • Restrict ICMP Message Types

    In <code>/etc/sysconfig/iptables</code>, the accepted ICMP messages types can be restricted. To accept only ICMP echo reply, destination unreachable, and time exceeded messages, remove the line:<br...
    Group
  • Log and Drop Packets with Suspicious Source Addresses

    Packets with non-routable source addresses should be rejected, as they may indicate spoofing. Because the modified policy will reject non-matching packets, you only need to add these rules if you a...
    Group

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