Procedimento hardening de Ubuntu

hardening

Versão: 1.0

Data: 30/04/2025

Autor: reginaldo.lopes@unesp.br

Política: Art. 42-VIII-D, Art. 32 Política de Segurança Cibernética

O que é

Hardening é o processo de reforçar a segurança de sistemas, servidores, aplicações e redes, reduzindo a superfície de ataque por meio da eliminação de vulnerabilidades, configurações padrão inseguras e serviços desnecessários.

Por que usar?

• Reduzir o risco de invasões e vazamentos.
• Cumprir normas e requisitos de compliance (CIS Controls, ISO 27001, etc).
• Minimizar o impacto de falhas zero-day.
• Aumentar a resiliência do ambiente contra ataques automatizados e direcionados

Uso

Passo 1: Criar um arquivo

touch hardening_ubuntu24.sh 

Passo 2: Permissão de execução

chmod +x hardening_ubuntu24.sh 

Passo 3: Copiar o código a baixo e colar no arquivo criado.

#!/bin/sh
### BEGIN INFO
# Reginaldo.lopes 30/04/2025
# Versão 1.0
### END INFO

case "$1" in

up)
echo "Iniciando ...                     [ OK ]"

# Verifica se é Ubuntu 24.04
LSB_SR=$(lsb_release -sr) ; LSB_SI=$(lsb_release -si)
if [ "$LSB_SR" = "24.04" ] && [ "$LSB_SI" = "Ubuntu" ] ; then 
	VER="U24"
  else
 		echo ""
		echo "Versao de sistema operacional invalido para este script"
		echo ""
		echo "Script homologado para Ubuntu  24.04 LTS"
		echo ""
		echo "Versao detectada:"
		echo "================="
		echo ""
		lsb_release -a
		echo ""
		echo "Saindo do programa"
		exit 1
fi

# Atualizar pacotes do sistema
echo "Atualizando pacotes do sistema..."
sudo apt update && sudo apt upgrade -y

# SSH
echo "Aplicando hardening no SSH..."
# Desativar encaminhamento X11, Rodar aplicações gráficas, ex: gedit
sudo sed -i 's/#X11Forwarding yes/X11Forwarding no/' /etc/ssh/sshd_config

# Desativar senhas vazias
sudo sed -i 's/#PermitEmptyPasswords yes/PermitEmptyPasswords no/' /etc/ssh/sshd_config

# Desativar encaminhamento TCP
echo "AllowTcpForwarding no" | sudo tee -a /etc/ssh/sshd_config

# Limitar tentativas de login SSH para mitigar ataques de força bruta
echo "MaxAuthTries 3" | sudo tee -a /etc/ssh/sshd_config

# Desativa completamente o login via SSH com o usuário root, mesmo com chave SSH.
# sudo sed -i 's/^#\?PermitRootLogin.*/PermitRootLogin no/' /etc/ssh/sshd_config

echo "Criando banner"
# Banner no ssh
# Adiciona o comando para chamar o banner
echo "Banner /etc/issue.net" | sudo tee -a /etc/ssh/sshd_config
# Adiciona o banner no arquivo issue.net
cat << EOF > /etc/issue.net
*****************************************************
*  UNESP - UNIVERSIDADE ESTADUAL PAULISTA           *
*                                                   *
*  ACESSO RESTRITO SOMENTE A PESSOAS AUTORIZADAS !  *
*                                                   *
*  Qualquer acesso nao autorizado podera resultar   *
*  em severas penalidades civis e criminais.        *
*                                                   *
*  Equipe CSIRT Unesp                               *
*  security@unesp.br                                *
*                                                   *
*****************************************************
EOF
########
sudo systemctl restart ssh

;;

*)
echo " "
echo "Description: \e[1;32m  \e[0m"
echo "Script para adicionar camadas de segurança no ubuntu 24.04"
echo " "
echo "Options: "
echo " "
echo "\e[0;32m Hardening: \e[0m"
echo "   - up             Iniciar o Hardening"
echo " "
echo "Example: "
echo "./hardening_ubuntu24.sh up"
echo "./hardening_ubuntu24.sh siem"
echo "./hardening_ubuntu24.sh firewall"
echo " "

;;
esac

Passo 4: Executar o script

./hardening_ubuntu24.sh 

• TODO:

Firewall

• EM DESENVOLVIMENTO.
• TODO: Adicionar no script /hardening_ubuntu24.sh firewall.

• firewallv4

#!/bin/sh
### BEGIN INIT INFO
# Provides:	     firewall 
# Required-Start:    $local_fs  $network $syslog
# Required-Stop:     $local_fs  $network $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: starts iptables rules
# Description:       starts iptables rules -  start-stop-daemon
### END INIT INFO

iptables=/sbin/iptables

case "$1" in
start)
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"
echo "| Script de Firewall IPv4 - IPTABLES"
echo "| Criado por: CSIRT UNESP"
echo "| security@unesp.br"
echo "| Uso: /etc/init.d/firewall start|stop|restart"
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"

echo ""
echo "Iniciando Firewall					[ OK ]"

iflo="lo"
ifext="< INTERFACE ex:eth0>"
ip="<IP ex:192.168.0.1>"
#monitor="< ZABBIX>"
ntp="200.145.255.25"

echo "Definindo variaveis					[ OK ]"

/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe iptable_filter
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_state
/sbin/modprobe ipt_REJECT
/sbin/modprobe ip_conntrack_tftp

echo "Carregamento de Modulos					[ OK ]"

$iptables -Z
$iptables -F
$iptables -X
$iptables -F -t nat
$iptables -X -t nat
$iptables -F -t mangle
$iptables -X -t mangle

echo "Zerando regras e tabelas				[ OK ]"

$iptables -I INPUT -d $ip -s 200.145.6.254 -j ACCEPT
$iptables -I OUTPUT -s $ip -d 200.145.6.254 -j ACCEPT
$iptables -P INPUT DROP
$iptables -P FORWARD DROP
$iptables -P OUTPUT DROP
$iptables -N valid-src
$iptables -N valid-dst
$iptables -N ssh-rules
$iptables -I INPUT -i $ifext -j valid-src
$iptables -I OUTPUT -o $ifext -j valid-dst


echo "Criando Politicas Padrao				[ OK ]"

#Regras de Seguranca
# Source and Destination Address Sanity Checks
# Drop packets from networks covered in RFC 1918 (private nets)
iptables -A valid-src -s 10.0.0.0/8     -j DROP
iptables -A valid-src -s 172.16.0.0/12  -j DROP
iptables -A valid-src -s 192.168.0.0/16 -j DROP
iptables -A valid-src -s 224.0.0.0/4    -j DROP
iptables -A valid-src -s 240.0.0.0/5    -j DROP
iptables -A valid-src -s 127.0.0.0/8    -j DROP
iptables -A valid-src -s 0.0.0.0/8       -j DROP
iptables -A valid-src -d 255.255.255.255 -j DROP
iptables -A valid-src -s 169.254.0.0/16  -j DROP
iptables -A valid-src -s $ip        -j DROP
iptables -A valid-dst -d 224.0.0.0/4    -j DROP

echo "BLOQUEIO DE IPs INVALIDOS				[ OK ]"

# Protecoes na pilha TCP/IP do Kernel
echo "BLOQUEIO DE ICMP BROADCAST				[ OK ]"
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
echo "PROTECAO CONTRA IP SPOOFING				[ OK ]"
echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
echo "BLOQUEIO DE REDIRECIONAMENTO ICMP			[ OK ]"
for f in /proc/sys/net/ipv4/conf/*/accept_redirects; do
	echo 0 >$f
done
echo "PROTECAO CONTRA SYNFLOOD				[ OK ]"
echo "1" > /proc/sys/net/ipv4/tcp_syncookies
echo "PROTECAO CONTRA RESPONSE BOGUS				[ OK ]"
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
echo "HABILITANDO SECURE REDIRECTS 				[ OK ]"
echo "1" > /proc/sys/net/ipv4/conf/all/secure_redirects
echo "PROTECAO CONTRA REDIRECIONAMENTOS DE ROTA		[ OK ]"
echo "0" > /proc/sys/net/ipv4/conf/all/accept_redirects
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
echo "SYN - FLOOD						[ OK ]"

$iptables -A INPUT -p icmp -d $ip --icmp-type echo-request -m limit --limit 1/s -j ACCEPT
$iptables -A INPUT -p icmp -d $ip --icmp-type echo-reply -m limit --limit 1/s -j ACCEPT
$iptables -A OUTPUT -p icmp -s $ip --icmp-type echo-request -m limit --limit 1/s -j ACCEPT
$iptables -A OUTPUT -p icmp -s $ip --icmp-type echo-reply -m limit --limit 1/s -j ACCEPT

echo "Aplicando limites ICMP					[ OK ]"

echo "Regras de Segurança Aplicadas				[ OK ]"

#Regras de INPUT
$iptables -A INPUT -p ALL  -m state --state ESTABLISHED,RELATED -j ACCEPT
$iptables -A INPUT -p tcp  -d $ip --dport 22 -j ssh-rules
#Regras de OUTPUT
$iptables -A OUTPUT -p ALL  -m state --state ESTABLISHED,RELATED -j ACCEPT
$iptables -A OUTPUT -s $ip -d $ntp -p udp --dport 123 -j ACCEPT
$iptables -A OUTPUT -p tcp  -s $ip --dport 53 -j ACCEPT
$iptables -A OUTPUT -p udp  -s $ip --dport 53 -j ACCEPT
$iptables -A OUTPUT -p tcp  -s $ip -m multiport --dport 80,443 -j ACCEPT

echo "Regras básicas de INPUT/FORWARD				[ OK ]"

$iptables -A INPUT -p ALL -i $iflo -j ACCEPT
$iptables -A OUTPUT -p ALL -o $iflo -j ACCEPT

echo "Habilitando Conexões Locais				[ OK ]"

# SSH - Liberações
$iptables -A ssh-rules -p tcp  -d $ip -s <IP Acesso SSH ex: 200.145.dti.dti> --dport 22 -j ACCEPT
$iptables -A ssh-rules -p tcp  -d $ip --dport 22 -j DROP

echo "Acesso SSH Restrito					[ OK ]"

#$iptables -A INPUT -p tcp -i $ifext -d $ip -s $monitor --dport 10050 -j ACCEPT
#echo "Acesso Zabbix						[ OK ]"

# Descomentar abaixo para serviço WEB
#$iptables -A INPUT -p tcp -s <IP para acessar sua pág> -d $ip -m multiport --dport 443,3000 -j ACCEPT
#echo "HTTPS 							[ OK ]"

# Descomentar abaixo para serviço MYSQL
#$iptables -A INPUT -p tcp  -d $ip --dport 3306 -j ACCEPT
#echo "MYSQL 			[ OK ]"

# Descomentar abaixo para serviço POSTGRE
#$iptables -A INPUT -p tcp  -d $ip --dport 5432 -j ACCEPT
#echo "POSTGRE 			[ OK ]"

# Descomentar abaixo para serviço de backup - Bacula
#$iptables -A INPUT -p udp -i $ifext -s <IP do bacula> -d $ip -m multiport --dport 9101:9103 -j ACCEPT
#$iptables -A INPUT -p tcp -i $ifext -s <IP do bacula> -d $ip -m multiport --dport 9101:9103 -j ACCEPT
#echo "Servidor Bacula			[ OK ]"


#service fail2ban restart
#echo "Restarting fail2ban service				[ OK ]"

echo "----------------------------------------------"
echo ""
echo ""
echo "Firewall Ativado"
echo ""
echo ""
;;

stop)
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"
echo "| Script de Firewall IPv4 - IPTABLES"
echo "| Criado por: CSIRT UNESP"
echo "| security@unesp.br"
echo "| Uso: /etc/init.d/firewall start|stop|restart"
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"

echo ""
echo "Parando Firewall					[ OK ]"

$iptables -P INPUT ACCEPT
$iptables -P FORWARD ACCEPT
$iptables -P OUTPUT ACCEPT

echo "Criando Politicas Padrao(ACCEPT)			[ OK ]"

$iptables -Z
$iptables -F
$iptables -X
$iptables -F -t nat
$iptables -X -t nat
$iptables -F -t mangle
$iptables -X -t mangle

echo "Zerando regras e tabelas				[ OK ]"	

echo ""
;;

restart)
 $0 stop
 sleep 2
 $0 start
#service fail2ban restart
;;
status)
# The 'status' option should return one of the LSB-defined return-codes,
# in particular, return-code 3 should mean that the service is not
# currently running. This is particularly important for Ansible's 'service'
# module, as without this behaviour it won't know if a service is up or down.
RETVAL=0
;;
*)
	echo " Usage: {start|stop|restart}"
;;
esac

• firewallv6

#!/bin/sh
### BEGIN INIT INFO
# Provides:	     firewallv6
# Required-Start:    $local_fs  $network $syslog
# Required-Stop:     $local_fs  $network $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: starts ip6tables rules
# Description:       starts ip6tables rules -  start-stop-daemon
### END INIT INFO

iptables=/sbin/ip6tables

case "$1" in
start)
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"
echo "| Script de Firewall IPv6 - IPTABLES"
echo "| Criado por: CSIRT UNESP"
echo "| security@unesp.br"
echo "| Uso: /etc/init.d/firewall start|stop|restart"
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"

echo ""
echo "Iniciando Firewall			[ OK ]"

iflo="lo"
ifext="< INTERFACE ex:eth0>"
ip="<IP ex2801:88:1000:bf::25> "
#netapp=""
#monitor="< ZABBIX>"
ntp="2801:88:ffff:b0b0::255"

echo "Definindo variaveis			[ OK ]"

/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe iptable_filter
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_state
/sbin/modprobe ipt_REJECT
/sbin/modprobe ip_conntrack_tftp

echo "Carregamento de Modulos			[ OK ]"

$iptables -Z
$iptables -F
$iptables -X
$iptables -F -t nat
$iptables -X -t nat
$iptables -F -t mangle
$iptables -X -t mangle

echo "Zerando regras e tabelas	[ OK ]"

$iptables -P INPUT DROP
$iptables -P FORWARD DROP
$iptables -P OUTPUT DROP
$iptables -N valid-src
$iptables -N valid-dst
$iptables -N ssh-rules
$iptables -I INPUT -i $ifext -j valid-src
$iptables -I OUTPUT -o $ifext -j valid-dst


echo "Criando Politicas Padrao	[ OK ]"

#Regras de Seguranca

echo 1 > /proc/sys/net/ipv4/tcp_syncookies
echo "SYN - FLOOD					[ OK ]"
echo "----------------------------------------------"
echo "Seguranca				[ OK ]"


#Regras de INPUT
$iptables -A INPUT -p ALL -m state --state ESTABLISHED,RELATED -j ACCEPT
$iptables -A INPUT -p ipv6-icmp -j ACCEPT
$iptables -A INPUT -p tcp -d $ip --dport 22 -j ssh-rules
#Regras de OUTPUT
$iptables -A OUTPUT -p ALL -m state --state ESTABLISHED,RELATED -j ACCEPT
$iptables -A OUTPUT -p ipv6-icmp -j ACCEPT
$iptables -A OUTPUT -s $ip -d $ntp -p udp --dport 123 -j ACCEPT
$iptables -A OUTPUT -p tcp -m state --state NEW  -s $ip --dport 53 -j ACCEPT
$iptables -A OUTPUT -s $ip -p udp --dport 53 -j ACCEPT
$iptables -A OUTPUT -p tcp -m state --state NEW  -s $ip --dport 80 -j ACCEPT
$iptables -A OUTPUT -p tcp -m state --state NEW  -s $ip --dport 443 -j ACCEPT


echo "Regras de INPUT/FORWARD			[ OK ]"

$iptables -A INPUT -p ALL -i $iflo -j ACCEPT
$iptables -A OUTPUT -p ALL -o $iflo -j ACCEPT

echo "Habilitando Conexões Locais		[ OK ]"

$iptables -A ssh-rules -p tcp -m state --state NEW  -d $ip -s <IP> --dport 22 -j ACCEPT


echo "Acesso SSH Restrito			[ OK ]"

#$iptables -A INPUT -p tcp -i $ifext -d $ip -s $monitor --dport 10050 -j ACCEPT
#$iptables -A OUTPUT -p tcp -o $ifext -s $ip -d $monitor --dport 10051 -j ACCEPT
#echo "Acesso Zabbix                             [ OK ]"


# Descomente abaixo para servidor WEB
#$iptables -A INPUT -p tcp -i $ifext -d $ip -m multiport --dport 80,443 -j ACCEPT
#echo "HTTP"

#$iptables -A INPUT -p udp -i $ifext -s XXXXXXXXXXXXX -d $ip -m multiport --dport 9101:9103 -j ACCEPT
#$iptables -A INPUT -p tcp -i $ifext -s XXXXXXXXXXXXX -d $ip -m multiport --dport 9101:9103 -j ACCEPT
#echo "Servidor Bacula			[ OK ]"

echo "----------------------------------------------"
echo ""
echo ""
echo "Firewall Ativado"
echo ""
echo ""
;;

stop)
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"
echo "| Script de Firewall IPv6 - IPTABLES"
echo "| Criado por: CSIRT UNESP"
echo "| security@unesp.br"
echo "| Uso: /etc/init.d/firewall start|stop|restart"
echo "::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::"

echo ""
echo "Parando Firewall			[ OK ]"
iptables=/sbin/ip6tables

$iptables -P INPUT ACCEPT
$iptables -P FORWARD ACCEPT
$iptables -P OUTPUT ACCEPT

echo "Criando Politicas Padrao(ACCEPT)	[ OK ]"

$iptables -Z
$iptables -F
$iptables -X
$iptables -F -t nat
$iptables -X -t nat
$iptables -F -t mangle
$iptables -X -t mangle

echo "Zerando regras e tabelas		[ OK ]"	

echo ""
;;

restart)
 $0 stop
 sleep 2
 $0 start
 service fail2ban restart
;;

*)
	echo " Usage: {start|stop|restart}"
;;
esac

Referências

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