Files
SecDep/harden
2023-09-05 05:23:12 +03:00

519 lines
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#!/usr/bin/env bash
# Ensure bash path is found
# shellcheck source=/etc/os-release
# use shellcheck to declare which file to source
# Using set to make the script safer
set -e # Exit on error
set -u # Exit on undefined variable
set -x # Print commands for debugging
set -a # Export all variables
set -C # Disable overwriting of files
set -o pipefail # Exit on pipe error
# set -euxaCo pipefail # All options
# Use the built-in trap command to catch error lines and signal numbers
trap 'printf "Error on line %d with signal %s" "$LINENO" "$?"' ERR # Exit on error
# Also use trap to catch interrupt signals and exit cleanly with a message to the user and a return code
trap 'printf "Interrupted on line %d with signal %s" "$LINENO" "$?"' INT SIGHUP SIGINT SIGTERM
# Get script name using parameter expansion to not spawn a new subprocess
SCRIPT_NAME="${0##*/}"
# We will be using printf instead of echo because it is more standardised.
# Also we will be using the test command's functionality as
# [[ because like this it constitutes a keyword and not a command.
# Functions will be defined as function "name" {body}" to make them
# more clear and () will not be used since using the keyword function renders them redundant
# We are taking for granted that the os-release file is in /etc as
# it has become a standard in most GNU/Linux distributions using systemd.
# We'll be using the -e flag just in case it is actually a symlink to another location.
# The get_distro function will use short if statements to check for the os-release file existence and readability.
# Then it will source it and output the distribution's name or exit in case of failure of either case.
function get_distro {
if [[ -e /etc/os-release ]] && [[ -r /etc/os-release ]]; then # Check if file exists and is readable
. /etc/os-release # Source the file
printf "%s" "$NAME" # Output the distribution's name
else # If the file does not exist or is not readable
printf "%s" "File os-release not found or not readable" # Output error message
exit 1 # Exit with error code 1
fi
}
# The get_package_manager function will take the output of the get_distro function and determine
# which is the package manager used for the most popular server distros and exit if it is not found.
function get_package_manager {
local distro # Declare distro as a local variable
distro="$(get_distro)" # Get the distribution name
case "$distro" in # Use case to check for the distribution name
"Ubuntu" | "Debian GNU/Linux") # If the distribution is Ubuntu or Debian
printf "%s" "apt" # Output apt
;;
"CentOS Linux" | "Fedora" | "Red Hat Enterprise Linux Server") # If the distribution is CentOS, Fedora or RHEL
printf "%s" "dnf" # Output dnf
;;
"openSUSE Leap") # If the distribution is OpenSUSE
printf "%s" "zypper" # Output zypper
;;
*)
# If the distribution is none of the above, output unsupported distribution
# and exit with error code 1
printf "%s" "Unsupported distribution"
exit 1 # Exit with error code 1
;;
esac
}
# The install_packages function will take the output of the get_package_manager function and install any
# package passed as an argument to it. It will also check if the package manager is known and exit if it is not.
function install_packages {
local package_manager # Declare package_manager as a local variable
package_manager="$(get_package_manager)" # Get the package manager
case "$package_manager" in # Use case to check for the package manager
"apt") # If the package manager is apt
printf "%s" 'debconf debconf/frontend select Noninteractive' | sudo debconf-set-selections
export DEBIAN_FRONTEND=noninteractive
export NEEDRESTART_MODE=a
export DEBIAN_PRIORITY=critical
# Running sudo with -E will preserve the environment variables set in the script
sudo -E apt update -y && sudo apt upgrade -y # Update the package list and upgrade the packages
sudo -E apt install -y "$@" # Install the packages passed as arguments
;;
"dnf") # If the package manager is dnf
sudo dnf upgrade -y # Update the package list
sudo dnf install -y "$@" # Install the packages passed as arguments
;;
"zypper") # If the package manager is zypper
sudo zypper update -y # Update the package list
sudo zypper install -y "$@" # Install the packages passed as arguments
;;
*)
# If the package manager is not one of the above, output unsupported package manager
# and exit with error code 1
printf "%s" "Unsupported package manager"
exit 1 # Exit with error code 1
;;
esac
}
# The check_dependencies function will check if the dependencies defined in a local array are not installed
# and store the ones that are indeed absent in another local array.
# Then it will install the packages that are missing by invoking the install_packages function.
function check_dependencies { # systemd-container is for machinectl
local dependencies=(fuse-overlayfs dbus-user-session uidmap slirp4netns systemd-container at htop curl git sudo vim ssh wget fail2ban) # Declare dependencies as a local array
#> see what to do with name differences between distros if any <#
local missing_dependencies=() # Declare missing_dependencies as a local array
for dependency in "${dependencies[@]}"; do # Loop through the dependencies array
# If the dependency is not installed, add it to the missing_dependencies array
! command -v "$dependency" &> /dev/null && missing_dependencies+=("$dependency")
done
# If the missing_dependencies array is not empty, install the packages
[[ ${#missing_dependencies[@]} -ne 0 ]] && install_packages "${missing_dependencies[@]}"
}
# Global array of the service names to be restarted
services=()
# The hardenSSH function will use sed to modify the sshd_config file to have the following settings:
# - Allow ssh access to users in the sudo group only
# - Change the port to 22100 if it is available
# - Configure idle timeout to 5 minutes
# - Limit the number of authentication attempts to 3
# - Disable root login
# - Disable empty passwords
# - Disable ssh protocol 1
# - Disable password authentication and only allow public key authentication
# - Disable X11 forwarding for security reasons (X11 forwarding is not needed for ssh)
# - Disable agent forwarding to prevent ssh-agent hijacking
# Then it will store the sshd service name in the services array.
function hardenSSH {
# Check if the sshd_config file exists and is readable
# If it is, then modify it using sed and restart the sshd service
# If it is not, then output an error message and exit with error code 1
# The -i flag is used to modify the file in place
# We split the sed command into multiple lines for readability purposes
# and to avoid calling it multiple times
if [[ -e /etc/ssh/sshd_config ]] && [[ -r /etc/ssh/sshd_config ]]; then
sudo sed -i \
-e 's/^#AllowGroups.*/AllowGroups sudo/' \
-e 's/^#Port.*/Port 22100/' \
-e 's/^#ClientAliveInterval.*/ClientAliveInterval 300/' \
-e 's/^#ClientAliveCountMax.*/ClientAliveCountMax 3/' \
-e 's/^#PermitRootLogin.*/PermitRootLogin no/' \
-e 's/^#PermitEmptyPasswords.*/PermitEmptyPasswords no/' \
-e 's/^#Protocol.*/Protocol 2/' \
-e 's/^#PasswordAuthentication.*/PasswordAuthentication no/' \
-e 's/^#X11Forwarding.*/X11Forwarding no/' \
-e 's/^X11Forwarding.*/X11Forwarding no/' \
-e 's/^#AllowAgentForwarding.*/AllowAgentForwarding no/' \
/etc/ssh/sshd_config
services+=("sshd") # Add sshd to the services array
else
printf "%s" "File sshd_config not found or not readable"
exit 1
fi
}
function getCorrectFirewall {
local distro # Declare distro as a local variable
distro="$(get_distro)" # Get the distribution name
case "$distro" in # Use case to check for the distribution name
"Ubuntu" | "Debian GNU/Linux") # If the distribution is Ubuntu or Debian
printf "%s" 'debconf debconf/frontend select Noninteractive' | sudo debconf-set-selections
export DEBIAN_FRONTEND=noninteractive
export NEEDRESTART_MODE=a
export DEBIAN_PRIORITY=critical
sudo -E apt install ufw -y # Install ufw
printf "%s" "ufw" # Output ufw
;;
"CentOS Linux" | "Fedora" | "Red Hat Enterprise Linux Server") # If the distribution is CentOS, Fedora or RHEL
sudo dnf install firewalld -y # Install firewalld
printf "%s" "firewalld" # Output firewalld
;;
"openSUSE Leap") # If the distribution is OpenSUSE
sudo zypper install firewalld -y # Install firewalld
printf "%s" "firewalld" # Output firewalld
;;
*)
# If the distribution is none of the above, output unsupported distribution
# and exit with error code 1
printf "%s" "Unsupported distribution"
exit 1 # Exit with error code 1
;;
esac
}
function getCorrectKernelSecurityModule {
local distro # Declare distro as a local variable
distro="$(get_distro)" # Get the distribution name
case "$distro" in # Use case to check for the distribution name
"Ubuntu") # If the distribution is Ubuntu
sudo apt install apparmor-profiles apparmor-utils apparmor-profiles-extra -y # Install apparmor
printf "%s" "apparmor" # Output apparmor
;;
"Debian GNU/Linux") # If the distribution is Debian
printf "%s" 'debconf debconf/frontend select Noninteractive' | sudo debconf-set-selections
export DEBIAN_FRONTEND=noninteractive
export NEEDRESTART_MODE=a
export DEBIAN_PRIORITY=critical
sudo -E apt install apparmor apparmor-profiles apparmor-profiles-extra apparmor-utils auditd python3-apparmor -y # Install apparmor
printf "%s" "apparmor" # Output apparmor
;;
"CentOS Linux" | "Fedora" | "Red Hat Enterprise Linux Server") # If the distribution is CentOS, Fedora or RHEL
sudo dnf install selinux container-selinux -y # Install selinux
printf "%s" "selinux" # Output selinux
;;
"openSUSE Leap") # If the distribution is OpenSUSE
sudo zypper install -t pattern apparmor -y # Install apparmor
printf "%s" "apparmor" # Output apparmor
;;
*)
# If the distribution is none of the above, output unsupported distribution
# and exit with error code 1
printf "%s" "Unsupported distribution"
exit 1 # Exit with error code 1
;;
esac
}
function firewallInit {
getCorrectFirewall # Get the correct firewall installed
# Determine if ufw or firewalld is installed
whereis ufw | grep -q /ufw && currentFirewall="ufw" || currentFirewall="firewalld"
case "$currentFirewall" in
ufw)
sudo ufw default allow outgoing # Allow outgoing connections
sudo ufw default deny incoming # Deny incoming connections
sudo ufw allow 22100/tcp # Allow ssh connections on port 22100
sudo ufw allow 8000/tcp # Allow portainer connections on port 8000
sudo ufw allow 9443/tcp # Allow portainer connections on port 9443
;;
firewalld)
sudo systemctl enable firewalld # Enable the firewall on boot
sudo firewall-cmd --permanent --add-port=22100/tcp # Allow ssh connections on port 22100
sudo firewall-cmd --permanent --add-port=8000/tcp # Allow portainer connections on port 8000
sudo firewall-cmd --permanent --add-port=9443/tcp # Allow portainer connections on port 9443
;;
*)
printf "%s" "Unsupported firewall"
exit 1
;;
esac
}
function kernelSecurityModuleInit {
getCorrectKernelSecurityModule # Get the correct kernel security module installed
# Determine if apparmor or selinux is installed
whereis apparmor | grep -q /apparmor && kernelSecurityModule="apparmor" || kernelSecurityModule="selinux"
case "$kernelSecurityModule" in
apparmor)
sudo systemctl enable --now apparmor # Enable the kernel security module on boot and start it
sudo aa-enforce /etc/apparmor.d/* # Enforce all apparmor profiles
;;
selinux)
sudo systemctl enable --now selinux # Enable the kernel security module on boot and start it
sudo setenforce 1 # Enforce selinux
sudo sed -i 's/^SELINUX=.*/SELINUX=enforcing/' /etc/selinux/config # Set selinux to enforcing
;;
*)
printf "%s" "Unsupported kernel security module"
exit 1
;;
esac
}
function dockerInit {
# Set up rootless docker
# Enable linger for the secdep user
sudo loginctl enable-linger secdep
# Enable dbus for the secdep user
sudo machinectl shell secdep@ /bin/bash -c "systemctl --user enable --now dbus"
# Install rootless docker
sudo machinectl shell secdep@ /bin/bash -c "curl -fsSL https://get.docker.com/rootless | sh"
# Add important environment variables to the secdep user's .bashrc
sudo su secdep << 'EOF'
printf "%s\n" "export PATH=/home/$USER/bin:$PATH" >> "$HOME/.bashrc"
printf "%s\n" "export DOCKER_HOST=unix:///run/user/$UID/docker.sock" >> "$HOME/.bashrc"
EOF
# Enable the user to bind to ports below 1024
sudo setcap cap_net_bind_service=ep /home/secdep/bin/rootlesskit
# Restart docker
sudo machinectl shell secdep@ /bin/bash -c "systemctl --user restart docker"
# Get all arguments passed to the function and store them in the dockerImages array
local dockerImages=("$@")
# Using -f instead of -e to check if the file exists AND that it is a regular file
[[ -f /root/docker-compose.yml ]] && sudo mv /root/docker-compose.yml /home/secdep/docker-compose.yml
[[ -f /home/admin/docker-compose.yml ]] && sudo mv /home/admin/docker-compose.yml /home/secdep/docker-compose.yml
[[ -f /home/ec2-user/docker-compose.yml ]] && sudo mv /home/ec2-user/docker-compose.yml /home/secdep/docker-compose.yml
[[ -f /home/centos/docker-compose.yml ]] && sudo mv /home/centos/docker-compose.yml /home/secdep/docker-compose.yml
[[ -f /home/fedora/docker-compose.yml ]] && sudo mv /home/fedora/docker-compose.yml /home/secdep/docker-compose.yml
[[ -f /home/ubuntu/docker-compose.yml ]] && sudo mv /home/ubuntu/docker-compose.yml /home/secdep/docker-compose.yml
# Since FileDeployment does not work and we used ScriptFileDeployment which might make the file owned by another user
# we need to make sure the file is owned by the secdep user.
# When using [[ -f /home/secdep/docker-compose.yml ]] && sudo chown secdep:secdep /home/secdep/docker-compose.yml
# it doesn't get executed somehow so we'll send the "no such file or directory" error to /dev/null
sudo chown secdep:secdep /home/secdep/docker-compose.yml > /dev/null 2>&1
# Since FileDeployment does not work and we used ScriptFileDeployment which automatically makes the file executable
# we need to make sure the file is not executable.
# when using [[ -f /home/secdep/docker-compose.yml ]] && sudo chmod -x /home/secdep/docker-compose.yml
# it doesn't get executed somehow so we'll send the "no such file or directory" error to /dev/null
sudo chmod -x /home/secdep/docker-compose.yml > /dev/null 2>&1
sudo machinectl shell secdep@ /bin/bash -c 'curl -SL https://github.com/docker/compose/releases/download/v2.20.3/docker-compose-linux-x86_64 -o /home/secdep/bin/docker-compose'
sudo machinectl shell secdep@ /bin/bash -c 'chmod +x /home/secdep/bin/docker-compose'
# Install gVisor
(
set -e
ARCH=$(uname -m)
URL=https://storage.googleapis.com/gvisor/releases/release/latest/${ARCH}
wget "${URL}"/runsc "${URL}"/runsc.sha512 \
"${URL}"/containerd-shim-runsc-v1 "${URL}"/containerd-shim-runsc-v1.sha512
sha512sum -c runsc.sha512 \
-c containerd-shim-runsc-v1.sha512
rm -f -- *.sha512
chmod a+rx runsc containerd-shim-runsc-v1
sudo mv runsc containerd-shim-runsc-v1 /home/secdep/bin
sudo chown secdep:secdep /home/secdep/bin/runsc
sudo chown secdep:secdep /home/secdep/bin/containerd-shim-runsc-v1
)
# Enable gVisor for docker by default while hardening the docker daemon.json file
# The no-new-privileges option will prevent the docker daemon from gaining new privileges
# The runsc option --network=host and --ignore-cgroups=true will help with running runsc
# with rootless docker without much hassle
sudo runuser - secdep -c 'mkdir -p /home/secdep/.config/docker'
# "icc": false to disable inter-container communication, does not work without br_netfilter module loaded
# and it is sometimes prohibited by the hosting provider
# so we'll leave it out
DOCKERD_CONFIG=$(cat <<'EOF'
{
"no-new-privileges": true,
"selinux-enabled": false,
"default-runtime": "runsc",
"runtimes": {
"runsc": {
"path": "/home/secdep/bin/runsc",
"runtimeArgs": [
"--network=host",
"--ignore-cgroups=true"
]
}
}
}
EOF
)
sudo runuser - secdep -c "printf '%s\n' '$DOCKERD_CONFIG' > /home/secdep/.config/docker/daemon.json"
# Restart docker to apply the changes
sudo machinectl shell secdep@ /bin/bash -c "systemctl --user restart docker"
whereis apparmor | grep -q /apparmor && kernelSecurityModule="apparmor" || kernelSecurityModule="selinux"
if [[ "$kernelSecurityModule" == "selinux" ]]; then
sudo chcon -Rt svirt_sandbox_file_t /home/secdep/.config/docker
sudo chcon -Rt svirt_sandbox_file_t /home/secdep/bin/runsc
setsebool -P container_manage_cgroup true
sudo runuser - secdep -c 'sed -i "s/\"selinux-enabled\": false/\"selinux-enabled\": true/" /home/secdep/.config/docker/daemon.json'
fi
sudo machinectl shell secdep@ "$(which bash)" -c '[[ -f "$HOME/docker-compose.yml" ]] && DOCKER_HOST=unix:///run/user/$UID/docker.sock /home/secdep/bin/docker-compose -f /home/secdep/docker-compose.yml up -d'
# Read the docker-compose.yml file for port mappings to add to the firewall
CMD_PORTS="cat /home/secdep/docker-compose.yml | sed '/^[[:space:]]*$/d' | grep -A1 ports | grep '[0-9]:[0-9]' | rev | cut -d':' -f1 | rev | grep -Eow '[[:digit:]]+' | tr '\n' ' '"
sudo -E runuser - secdep -c "$CMD_PORTS" > /dev/null 2>&1 && PORTS="$(sudo -E runuser - secdep -c "$CMD_PORTS")" || PORTS=""
# Loop through the ports in the PORTS variable
if [[ -n "$PORTS" ]]; then
for port in $PORTS; do
# Allow the port in the firewall
case "$currentFirewall" in
ufw)
sudo ufw allow "$port"/tcp
;;
firewalld)
sudo firewall-cmd --permanent --add-port="$port"/tcp
;;
*)
printf "%s" "Unsupported firewall"
exit 1
;;
esac
done
fi
# Portainer is a docker image that provides a web interface for docker
# which will be installed and run on port 9443 by default to make it easier to manage docker
# url to follow after the installation is complete: https://vps_ip:9443
# the https:// part is important as portainer will not work without it
sudo -E runuser - secdep -c 'docker run -d -p 8000:8000 -p 9443:9443 --name=portainer --restart=always -v /run/user/$UID/docker.sock:/var/run/docker.sock -v portainer_data:/data portainer/portainer-ce'
# Check if the dockerImages array is empty and return 0 if it is
[[ "${#dockerImages[@]}" -eq 0 ]] && return 0
# Loop through the dockerImages array
# The dockerImages array contains all the docker images to install and run
for dockerImage in "${dockerImages[@]}"; do
# If dockerImage contains a ":" character (if it is a docker image with a tag)
# then store the docker image name in the dockerImageName variable
[[ "$dockerImage" == *":"* ]] && dockerImageName="${dockerImage%:*}" || dockerImageName="$dockerImage"
# Same goes for "/"
[[ "$dockerImageName" == *"/"* ]] && dockerImageName="${dockerImageName%/*}"
CMD="docker pull $dockerImage"
printf "%s\n" "Downloaded $dockerImageName docker image"
sudo -E runuser - secdep -c "$CMD"
done
}
function configureFail2ban {
FAIL2BAN_LOCAL=$(cat <<'EOF'
[Definition]
allowipv6 = auto
EOF
)
printf "%s\n" "$FAIL2BAN_LOCAL" | sudo tee /etc/fail2ban/fail2ban.local
FAIL2BAN_SSH_JAIL_LOCAL=$(cat <<'EOF'
[sshd]
enabled = true
filter = sshd
banaction = iptables
backend = systemd
maxretry = 3
# 3 failed attempts in 600 seconds = 10 minutes
findtime = 1d
bantime = 1d
ignoreip = 127.0.0.1/8
EOF
)
FAIL2BAN_JAIL_LOCAL=$(cat <<'EOF'
[DEFAULT]
bantime = 1d
EOF
)
printf "%s\n" "$FAIL2BAN_JAIL_LOCAL" | sudo tee /etc/fail2ban/jail.local
sudo rm -f /etc/fail2ban/jail.d/*
printf "%s\n" "$FAIL2BAN_SSH_JAIL_LOCAL" | sudo tee /etc/fail2ban/jail.d/sshd.local
FAIL2BAN_FILTER=$(cat <<'EOF'
[Definition]
failregex = ^.*DROP_.*SRC=<ADDR> DST=.*$
journalmatch = _TRANSPORT=kernel
EOF
)
printf "%s\n" "$FAIL2BAN_FILTER" | sudo tee /etc/fail2ban/filter.d/fwdrop.local
sudo systemctl enable --now fail2ban
printf "%s\n" "LogLevel VERBOSE" | sudo tee -a /etc/ssh/sshd_config
}
function enableServices {
for service in "${services[@]}"; do
sudo systemctl restart "$service"
done
whereis ufw | grep -q /ufw && currentFirewall="ufw" || currentFirewall="firewalld"
# With the if block it doesn't error out at firewalld check so we do it this way
# For ufw
if [[ "$currentFirewall" == "ufw" ]]; then
# Enable the firewall
sudo ufw --force enable
# Enable and start the firewall on boot
sudo systemctl enable --now ufw
# For firewalld
elif [[ "$currentFirewall" == "firewalld" ]]; then
# Reload the firewall
sudo firewall-cmd --reload
else
printf "%s" "Somehow there is no firewall installed"
exit 1
fi
}
# Sometimes the user is not deleted after the script is run
function deleteRemainingUsers {
# In case atd wasn't running
sudo systemctl enable --now atd
# Set the correct timezone for Greece before using at
sudo timedatectl set-timezone Europe/Athens
# Delete possible remaining users
cat << EOF | sudo tee /root/delete_users.sh
[[ -d /home/admin ]] && sudo userdel -r admin && sudo groupdel admin
[[ -d /home/ec2-user ]] && sudo userdel -r ec2-user && sudo groupdel ec2-user
[[ -d /home/centos ]] && sudo userdel -r centos && sudo groupdel centos
[[ -d /home/fedora ]] && sudo userdel -r fedora && sudo groupdel fedora
[[ -d /home/ubuntu ]] && sudo userdel -r ubuntu && sudo groupdel ubuntu
sudo rm -f /root/delete_users.sh
EOF
# Restart atd after setting the timezone
sudo systemctl restart atd
# Use at as root because if it is run as one of the users above it will fail
sudo at now + 1 minute <<< "bash /root/delete_users.sh"
}
# The main function will call the declared functions in order and exit if any of them fails.
# It will also pass any arguments passed to the script to the dockerInit function.
# Then it will output a message to the user and reboot the system in 2 minutes.
function main {
printf "%s" "$SCRIPT_NAME script started"
check_dependencies || exit 1 # Check dependencies and exit if it fails
printf "%s" "Dependencies installed"
hardenSSH || exit 1 # Harden ssh and exit if it fails
printf "%s" "SSH hardened"
firewallInit || exit 1 # Initialize the firewall and exit if it fails
printf "%s" "Firewall initialized"
kernelSecurityModuleInit || exit 1 # Initialize the kernel security module and exit if it fails
printf "%s" "Kernel security module initialized"
configureFail2ban || exit 1 # Initialize fail2ban and exit if it fails
printf "%s" "Fail2ban configured"
# Call the dockerInit function with the arguments passed to the script
dockerInit "$@" || exit 1 # Initialize docker and exit if it fails
printf "%s" "Docker Rootless, docker-compose and gVisor installed and configured"
printf "%s" "Portainer along with any specified docker images from the command line or a docker-compose.yml file installed"
enableServices || exit 1 # Enable the services that need to be restarted and the firewall
printf "%s" "Services restarted and firewall enabled"
deleteRemainingUsers || exit 1 # Delete possible remaining users
printf "%s" "Any unnecessary users deleted"
printf "%s" "$SCRIPT_NAME script finished" # Output message to the user
printf "%s" "System will reboot momentarily" # Output message to the user
# Reboot the system in 2 minutes with the shutdown command so that login before the reboot is not possible
sudo shutdown -r +2
}
# Call the main function
main "$@"
exit 0 # The right and proper way to exit a script