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Shield.sh
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Shield.sh
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#!/bin/bash
auditd_configuration() {
# Installs auditd
apt install auditd
# Configures auditd
echo "
# Removes any existing auditd rules
-D
# Sets the buffer size, which may need to be increased, depending on the load of your system.
-b 8192
# Sets the failure mode to Failure Mode 1, which prints a failure message.
-f 2
# Audits the audit logs.
-w /var/log/audit/ -k auditlog
# Modifies the audit configuration,that occurs during the audit.
-w /etc/libaudit.conf -p wa -k auditconfig
-w /etc/audit/ -p wa -k auditconfig
-w /etc/audisp/ -p wa -k audispconfig
# Audits, user, group, and password databases
-w /etc/group -p wa -k etcgroup
-w /etc/passwd -p wa -k etcpasswd
-w /etc/gshadow -k etcgroup
-w /etc/shadow -k etcpasswd
-w /etc/security/opasswd -k opasswd
# Tools to change group identifiers
-w /usr/sbin/usermod -p x -k user_modification
-w /usr/sbin/addgroup -p x -k group_modification
-w /usr/sbin/adduser -p x -k user_modification
-w /usr/sbin/groupadd -p x -k group_modification
-w /usr/sbin/useradd -p x -k user_modification
-w /usr/sbin/groupmod -p x -k group_modification
# Monitors usage of passwd command
-w /usr/bin/passwd -p x -k passwd_modification
# Schedules cronjobs
-w /etc/cron.monthly/ -p wa -k cron
-w /etc/cron.hourly/ -p wa -k cron
-w /etc/crontab -p wa -k cron
-w /etc/cron.weekly/ -p wa -k cron
-w /etc/cron.d/ -p wa -k cron
-w /etc/cron.deny -p wa -k cron
-w /etc/cron.daily/ -p wa -k cron
-w /etc/cron.allow -p wa -k cron
-w /var/spool/cron/crontabs/ -k cron
# Login configuration and information
-w /etc/login.defs -p wa -k login
-w /etc/securetty -p wa -k login
-w /var/log/faillog -p wa -k login
-w /var/log/lastlog -p wa -k login
-w /var/log/tallylog -p wa -k login
# Network Environment
-w /etc/network/ -p wa -k network
-w /etc/hosts -p wa -k hosts
# Library search paths
-w /etc/ld.so.conf -p wa -k libpath
# Kernel parameters and module loading and unloading
-w /etc/sysctl.conf -p wa -k sysctl
-a always,exit -F perm=x -F auid!=-1 -F path=/sbin/insmod -k modules
-a always,exit -F perm=x -F auid!=-1 -F path=/sbin/modprobe -k modules
-a always,exit -F perm=x -F auid!=-1 -F path=/sbin/rmmod -k modules
-a always,exit -F arch=b64 -S finit_module -S init_module -S delete_module -F auid!=-1 -k modules
-a always,exit -F arch=b32 -S finit_module -S init_module -S delete_module -F auid!=-1 -k modules
# System startup scripts
-w /etc/init.d/ -p wa -k init
-w /etc/init/ -p wa -k init
-w /etc/inittab -p wa -k init
# SSH configuration
-w /etc/ssh/sshd_config -k sshd
# Changes to hostname
-a exit,always -F arch=b32 -S sethostname -k hostname
-a exit,always -F arch=b64 -S sethostname -k hostname
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k network_modifications
-a always,exit -F arch=b64 -S sethostname -S setdomainname -k network_modifications
# Captures all failures to access on critical elements
-a exit,always -F arch=b64 -S open -F dir=/usr/local/bin -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/bin -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/var -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/sbin -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/home -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/usr/sbin -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/srv -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/usr/bin -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/etc -F success=0 -k unauthedfileacess
# Logs all commands executed by root
-a exit,always -F arch=b64 -F euid=0 -S execve -k rootcmd
-a exit,always -F arch=b32 -F euid=0 -S execve -k rootcmd
# Su and Sudo
-w /etc/sudoers -p rw -k priv_esc
-w /usr/bin/sudo -p x -k priv_esc
-w /bin/su -p x -k priv_esc
# Poweroffs and reboots tools
-w /sbin/shutdown -p x -k power
-w /sbin/halt -p x -k power
-w /sbin/poweroff -p x -k power
-w /sbin/reboot -p x -k power
# Monitors for use of audit management tools
-w /sbin/auditd -p x -k audittools
-w /sbin/auditctl -p x -k audittools
# Prevents chrony from overwhelming the logs
-a never,exit -F arch=b64 -S adjtimex -F auid=unset -F uid=chrony -F subj_type=chronyd_t
# Ignore End of Event records
-a always,exclude -F msgtype=EOE
# Ignore current working directory records
-a always,exclude -F msgtype=CWD
# VMWare tools
-a exit,never -F arch=b32 -S fork -F success=0 -F path=/usr/lib/vmware-tools -F subj_type=initrc_t -F exit=-2
-a exit,never -F arch=b64 -S fork -F success=0 -F path=/usr/lib/vmware-tools -F subj_type=initrc_t -F exit=-2
# High Volume Event Filter
-a exit,never -F arch=b32 -F dir=/dev/shm -k sharedmemaccess
-a exit,never -F arch=b64 -F dir=/dev/shm -k sharedmemaccess
-a exit,never -F arch=b32 -F dir=/var/lock/lvm -k locklvm
-a exit,never -F arch=b64 -F dir=/var/lock/lvm -k locklvm
# Modprobe configuration
-w /etc/modprobe.conf -p wa -k modprobe
# KExec usage
-a always,exit -F arch=b32 -S sys_kexec_load -k KEXEC
-a always,exit -F arch=b64 -S kexec_load -k KEXEC
# Special files
-a exit,always -F arch=b32 -S mknod -S mknodat -k specialfiles
-a exit,always -F arch=b64 -S mknod -S mknodat -k specialfiles
# Mount operations
-a always,exit -F arch=b64 -S mount -S umount2 -F auid!=-1 -k mount
-a always,exit -F arch=b32 -S mount -S umount -S umount2 -F auid!=-1 -k mount
# Local time zone
-w /etc/localtime -p wa -k localtime
# Stunnel
-w /usr/sbin/stunnel -p x -k stunnel
# Sudoers file changes
-w /etc/sudoers -p wa -k actions
# Changes to other files
-a always,exit -F dir=/etc/NetworkManager/ -F perm=wa -k network_modifications
-w /etc/sysconfig/network -p wa -k network_modifications
-w /etc/hosts -p wa -k network_modifications
-w /etc/sysconfig/network -p wa -k network_modifications
-w /etc/network/ -p wa -k network
# Time
-a exit,always -F arch=b32 -S adjtimex -S settimeofday -S clock_settime -k time
-a exit,always -F arch=b64 -S adjtimex -S settimeofday -S clock_settime -k time
# Changes to /etc/issue
-w /etc/issue -p wa -k etcissue
-w /etc/issue.net -p wa -k etcissu
# Change swap
-a always,exit -F arch=b64 -S swapon -S swapoff -F auid!=-1 -k swap
-a always,exit -F arch=b32 -S swapon -S swapoff -F auid!=-1 -k swap
# Pam configuration
-w /etc/security/namespace.conf -p wa -k pam
-w /etc/security/namespace.init -p wa -k pam
-w /etc/security/limits.conf -p wa -k pam
-w /etc/pam.d/ -p wa -k pam
-w /etc/security/pam_env.conf -p wa -k pam
# Systemd
-w /bin/systemctl -p x -k systemd
-w /etc/systemd/ -p wa -k systemd
# Process ID change applications
-w /bin/su -p x -k priv_esc
-w /usr/bin/sudo -p x -k priv_esc
-w /etc/sudoers -p rw -k priv_esc
# Session initiation information
-w /var/run/utmp -p wa -k session
-w /var/log/btmp -p wa -k session
-w /var/log/wtmp -p wa -k session
# Discretionary Access Control (DAC) modifications
-a always,exit -F arch=b32 -S chmod -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fchmod -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fchmodat -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fchown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fchownat -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S fsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S lchown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S lremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S lsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S removexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S chmod -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S chown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fchmod -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fchmodat -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fchown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fchownat -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S fsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S lchown -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S lremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S lsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S removexattr -F auid>=500 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S setxattr -F auid>=500 -F auid!=4294967295 -k perm_mod
# Suspicious activities
-w /usr/bin/wireshark -p x -k susp_activity
-w /usr/bin/ssh -p x -k susp_activity
-w /usr/bin/curl -p x -k susp_activity
-w /usr/bin/ncat -p x -k susp_activity
-w /usr/bin/base64 -p x -k susp_activity
-w /usr/bin/wget -p x -k susp_activity
-w /usr/bin/rawshark -p x -k susp_activity
-w /bin/nc -p x -k susp_activity
-w /usr/bin/rdesktop -p x -k sbin_susp
-w /bin/netcat -p x -k susp_activity
-w /usr/bin/socat -p x -k susp_activity
# Sbin suspicious activity
-w /usr/sbin/traceroute -p x -k sbin_susp
-w /sbin/ifconfig -p x -k sbin_susp
-w /usr/sbin/tcpdump -p x -k sbin_susp
-w /sbin/iptables -p x -k sbin_susp
# Reconnaissance and information gathering
-w /usr/bin/whoami -p x -k recon
-w /etc/hostname -p r -k recon
-w /etc/issue -p r -k recon
# Injection, these rules watch for code injection by the ptrace facility
# This could indicate someone trying to do something malicious or just debugging
-a always,exit -F arch=b32 -S ptrace -k tracing
-a always,exit -F arch=b64 -S ptrace -k tracing
-a always,exit -F arch=b32 -S ptrace -F a0=0x4 -k code_injection
-a always,exit -F arch=b64 -S ptrace -F a0=0x4 -k code_injection
-a always,exit -F arch=b32 -S ptrace -F a0=0x5 -k data_injection
-a always,exit -F arch=b64 -S ptrace -F a0=0x5 -k data_injection
-a always,exit -F arch=b32 -S ptrace -F a0=0x6 -k register_injection
-a always,exit -F arch=b64 -S ptrace -F a0=0x6 -k register_injection
# Privilege Abuse, the purpose of this rule is to detect when an admin may be abusing power by looking in user's home directory.
-a always,exit -F dir=/home -F uid=0 -F auid>=1000 -F auid!=4294967295 -C auid!=obj_uid -k power_abuse
# Apt-get and dpkg
-w /usr/bin/apt-get -p x -k software_mgmt
-w /usr/bin/apt-add-repository -p x -k software_mgmt
-w /usr/bin/aptitude -p x -k software_mgmt
-w /usr/bin/dpkg -p x -k software_mgmt
# CHEF
-w /etc/chef -p wa -k soft_chef
# GDS specific secrets
-w /etc/puppet/ssl -p wa -k puppet_ssl
#IBM Bigfix BESClient
-a exit,always -F arch=b64 -S open -F dir=/opt/BESClient -F success=0 -k soft_besclient
-w /var/opt/BESClient/ -p wa -k soft_besclient
# Root command executions
-a exit,always -F arch=b64 -F euid=0 -S execve -k rootcmd
-a exit,always -F arch=b32 -F euid=0 -S execve -k rootcmd
# Unauthorized file Access
-a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k file_access
-a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k file_access
-a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k file_access
-a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k file_access
# File Deletion Events by User
-a always,exit -F arch=b32 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete
-a always,exit -F arch=b64 -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete
# Unsuccessful Creation
-a always,exit -F arch=b32 -S creat,link,mknod,mkdir,symlink,mknodat,linkat,symlinkat -F exit=-EACCES -k file_creation
-a always,exit -F arch=b64 -S mkdir,creat,link,symlink,mknod,mknodat,linkat,symlinkat -F exit=-EACCES -k file_creation
-a always,exit -F arch=b32 -S link,mkdir,symlink,mkdirat -F exit=-EPERM -k file_creation
-a always,exit -F arch=b64 -S mkdir,link,symlink,mkdirat -F exit=-EPERM -k file_creation
# Unsuccessful Modification
-a always,exit -F arch=b32 -S rename -S renameat -S truncate -S chmod -S setxattr -S lsetxattr -S removexattr -S lremovexattr -F exit=-EACCES -k file_modification
-a always,exit -F arch=b64 -S rename -S renameat -S truncate -S chmod -S setxattr -S lsetxattr -S removexattr -S lremovexattr -F exit=-EACCES -k file_modification
-a always,exit -F arch=b32 -S rename -S renameat -S truncate -S chmod -S setxattr -S lsetxattr -S removexattr -S lremovexattr -F exit=-EPERM -k file_modification
-a always,exit -F arch=b64 -S rename -S renameat -S truncate -S chmod -S setxattr -S lsetxattr -S removexattr -S lremovexattr -F exit=-EPERM -k file_modification
# Makes the configuration immutable
-e 2
" > /etc/audit/rules.d/audit.rules
systemctl enable auditd.service
service auditd restart
}
automatic_updates() {
# Enables automatic updates
apt-get install unattended-upgrades
dpkg-reconfigure -plow unattended-upgrades
}
disable_core_dumps() {
# Disables core dumps
echo "* hard core 0" >> /etc/security/limits.conf
echo "ulimit -c 0" >> /etc/profile
echo "ProcessSizeMax=0
Storage=none" >> /etc/systemd/coredump.conf
}
disable_firewire() {
# Disables firewire
echo "install udf /bin/true
blacklist firewire-core
blacklist firewire-ohci
blacklist firewire-sbp2" >> /etc/modprobe.d/blacklist.conf
}
disable_usb() {
# Disables usb
echo "blacklist usb-storage" >> /etc/modprobe.d/blacklist.conf
}
disable_uncommon_filesystems() {
# Disables uncommon filesystems
echo "install cramfs /bin/true
install freevxfs /bin/true
install hfs /bin/true
install hfsplus /bin/true
install jffs2 /bin/true
install squashfs /bin/true" >> /etc/modprobe.d/filesystems.conf
}
disable_uncommon_network_protocols() {
# Disables uncommon network protocols
echo "install dccp /bin/true
install sctp /bin/true
install tipc /bin/true
install rds /bin/true" >> /etc/modprobe.d/protocols.conf
apt-get --purge remove xinetd nis yp-tools tftpd atftpd tftpd-hpa telnetd rsh-server rsh-redone-server
}
setup_fail2ban() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs fail2ban
apt install fail2ban
# Enable fail2ban
systemctl start fail2ban && systemctl enable fail2ban
# Sets up fail2ban
echo -n "Would you like to change the ssh port on your system [y/N]?"
read -r qw
if [ "$qw" == "y" ]
then
echo -n "Please enter the port you like to change the ssh port to: "
read -r ty
echo"
bantime = 86400
findtime = 300
maxretry = 3
backend = systemd
banaction = iptables-multiport
banaction_allports = iptables-allports
[sshd]
enabled = true
[ssh]
enabled = true
port = $ty
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
" >> nano /etc/fail2ban/jail.local
fi
if [ "$qw" == "N" ]
then
echo "
bantime = 86400
findtime = 300
maxretry = 3
backend = systemd
banaction = iptables-multiport
banaction_allports = iptables-allports
[sshd]
enabled = true
[ssh]
enabled = true
port = 22
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
" >> nano /etc/fail2ban/jail.local
fi
# Restarts fail2ban
service fail2ban restart
}
iptable_configuration() {
# Installs Iptables
apt install iptables-persistent
# Flushes existing iptable rules
iptables -F
# Logs and drops packets
iptables -A INPUT -i eth1 -s 10.0.0.0/8 -j LOG --log-prefix "IP_SPOOF A: "
iptables -A INPUT -i eth1 -s 10.0.0.0/8 -j DROP
# Maintains a list of recent connections to match against
iptables -A FORWARD -m recent --name portscan --rcheck --seconds 100 -j DROP
iptables -A FORWARD -p tcp -i eth0 --dport 443 -m recent --name portscan --set -j DROP
# Matching against a string in a packet's data payload
iptables -A FORWARD -m string --string '.com' -j DROP
iptables -A FORWARD -m string --string '.exe' -j DROP
# Time-based rules
iptables -A FORWARD -p tcp -m multiport --dport http,https -o eth0 -i eth1 -m time --timestart 21:30 --timestop 22:30 --days Mon,Tue,Wed,Thu,Fri -j ACCEPT
# Packet matching based on TTL values
iptables -A INPUT -s 1.2.3.4 -m ttl --ttl-lt 40 -j REJECT
# Configures Iptable Defaults
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
# Drops Spoofing attacks
iptables -A INPUT -s 10.0.0.0/8 -j DROP
iptables -A INPUT -s 169.254.0.0/16 -j DROP
iptables -A INPUT -s 172.16.0.0/12 -j DROP
iptables -A INPUT -s 127.0.0.0/8 -j DROP
iptables -A INPUT -s 192.168.0.0/24 -j DROP
iptables -A INPUT -s 224.0.0.0/4 -j DROP
iptables -A INPUT -d 224.0.0.0/4 -j DROP
iptables -A INPUT -s 240.0.0.0/5 -j DROP
iptables -A INPUT -d 240.0.0.0/5 -j DROP
iptables -A INPUT -s 0.0.0.0/8 -j DROP
iptables -A INPUT -d 0.0.0.0/8 -j DROP
iptables -A INPUT -d 239.255.255.0/24 -j DROP
iptables -A INPUT -d 255.255.255.255 -j DROP
# Accepts loopback input
iptables -A INPUT -i lo -p all -j ACCEPT
# Allows a three-way Handshake
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# Drops packets with excessive RST to avoid Masked attacks
iptables -A INPUT -p tcp -m tcp --tcp-flags RST RST -m limit --limit 2/second --limit-burst 2 -j ACCEPT
# Stops Masked Attacks
iptables -A INPUT -p icmp --icmp-type 13 -j DROP
iptables -A INPUT -p icmp --icmp-type 14 -j DROP
iptables -A INPUT -p icmp --icmp-type 17 -j DROP
iptables -A INPUT -p icmp -m limit --limit 1/second -j ACCEPT
# Discards Invalid Packets
iptables -A INPUT -m state --state INVALID -j DROP
iptables -A FORWARD -m state --state INVALID -j DROP
iptables -A OUTPUT -m state --state INVALID -j DROP
# Allows ssh
iptables -A INPUT -p tcp -m tcp --dport 652 -j ACCEPT
# Allow one ssh connection at a time
iptables -A INPUT -p tcp --syn --dport 652 -m connlimit --connlimit-above 2 -j REJECT
# Allows Ping
iptables -A INPUT -p icmp --icmp-type 0 -j ACCEPT
# Protection against port scanning
iptables -N port-scanning
iptables -A port-scanning -p tcp --tcp-flags SYN,ACK,FIN,RST RST -m limit --limit 1/s --limit-burst 2 -j RETURN
iptables -A port-scanning -j DROP
# SSH brute-force protection
iptables -A INPUT -p tcp --dport ssh -m conntrack --ctstate NEW -m recent --set
iptables -A INPUT -p tcp --dport ssh -m conntrack --ctstate NEW -m recent --update --seconds 60 --hitcount 10 -j DROP
# Syn-flood protection
iptables -N syn_flood
iptables -A INPUT -p tcp --syn -j syn_flood
iptables -A syn_flood -m limit --limit 1/s --limit-burst 3 -j RETURN
iptables -A syn_flood -j DROP
iptables -A INPUT -p icmp -m limit --limit 1/s --limit-burst 1 -j ACCEPT
iptables -A INPUT -p icmp -m limit --limit 1/s --limit-burst 1 -j LOG --log-prefix PING-DROP:
iptables -A INPUT -p icmp -j DROP
iptables -A OUTPUT -p icmp -j ACCEPT
# Mitigating SYN floods with SYNPROXY
iptables -t raw -A PREROUTING -p tcp -m tcp --syn -j CT --notrack
iptables -A INPUT -p tcp -m tcp -m conntrack --ctstate INVALID,UNTRACKED -j SYNPROXY --sack-perm --timestamp --wscale 7 --mss 1460
iptables -A INPUT -m conntrack --ctstate INVALID -j DROP
# Block new packets that aren't SYN packets
iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP
# Force fragments packets check
iptables -A INPUT -f -j DROP
# XMAS packets
iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP
# Drop all null packets
iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP
# Block uncommon MSS values
iptables -t mangle -A PREROUTING -p tcp -m conntrack --ctstate NEW -m tcpmss ! --mss 536:65535 -j DROP
# Block packets with bogus TCP flags
iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,RST FIN,RST -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,ACK FIN -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,URG URG -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,FIN FIN -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,PSH PSH -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL ALL -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL NONE -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,FIN,PSH,URG -j DROP
iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
# Drops connections if the ip address makes more than 5 connection attempts to port 80 within 50 seconds
$IPT -I INPUT -p tcp --dport 80 -i eth0 -m state --state NEW -m recent --set
$IPT -I INPUT -p tcp --dport 80 -i eth0 -m state --state NEW -m recent --update --seconds 50 --hitcount 5 -j DROP
# Saves iptables rules
iptables-save > /etc/iptables/rules.v4
ip6tables-save > /etc/iptables/rules.v6
# Starts iptables
sudo ufw enable
}
kernel_configuration() {
# Configures the kernel
echo "net.ipv4.tcp_syncookies: 1
net.ipv4.tcp_synack_retries = 5
net.ipv4.conf.default.accept_source_route: 0
kernel.core_uses_pid: 1
net.ipv4.conf.default.rp_filter: 1
net.ipv4.conf.all.log_martians: 1
kernel.kptr_restrict: 2
net.ipv4.conf.default.secure_redirects: 1
net.ipv4.conf.default.accept_redirects: 0
kernel.sysrq: 0
net.ipv4.icmp_echo_ignore_all: 0
net.ipv4.ip_forward: 0
fs.protected_symlinks: 1
net.ipv4.tcp_rfc1337: 1
net.ipv4.icmp_echo_ignore_broadcasts: 1
net.ipv4.conf.all.rp_filter: 1
net.ipv4.conf.all.send_redirects: 0
net.ipv6.conf.all.forwarding: 0
net.ipv4.conf.all.accept_source_route: 0
net.ipv6.conf.default.accept_source_route: 0
net.ipv4.conf.default.log_martians: 1
net.ipv6.conf.all.accept_source_route: 0
net.ipv4.conf.all.secure_redirects: 1
fs.protected_hardlinks: 1
net.ipv4.conf.all.accept_redirects: 0
kernel.perf_event_paranoid: 2
net.ipv4.conf.default.send_redirects: 0
kernel.randomize_va_space: 2
net.ipv6.conf.all.accept_redirects: 0
net.ipv6.conf.default.accept_redirects: 0
net.ipv4.icmp_ignore_bogus_error_responses: 1
net.ipv4.conf.all.promote_secondaries : 1
fs.file-max : 65535
net.ipv4.ip_local_port_range : 2000 65000
net.core.rmem : 8388608
net.core.wmem_max : 8388608
net.core.netdev_max_backlog : 5000
net.ipv4.tcp_window_scaling : 1
kernel.exec-shield : 2
kernel.randomize_va_space : 2
net.ipv4.tcp_rmem : 4096 87380 8388608
net.ipv4.tcp_wmem : 4096 87380 8388608
net.ipv4.tcp_rfc1337 : 1
net.ipv6.conf.default.max_addresses : 1
net.ipv6.conf.default.dad_transmits : 0
net.ipv6.conf.default.autoconf : 0
net.ipv6.conf.default.accept_ra_defrtr : 0
net.ipv6.conf.default.accept_ra_pinfo : 0
net.ipv6.conf.default.router_solicitations : 0
kernel.panic : 10
kernel.randomize_va_space : 2
fs.protected_hardlinks : 1
fs.protected_symlinks : 1
kernel.yama.ptrace_scope: 1" > /etc/sysctl.d/80-lockdown.conf
sysctl --system
}
legal_banner() {
# Adds a legal banner to /etc/motd, /etc/issue and /etc/issue.net
echo "
Unauthorized access to this server is prohibited.
All connections are monitored and recorded.
Legal action will be taken. Please disconnect now.
" > /etc/motd
echo "
Unauthorized access to this server is prohibited.
All connections are monitored and recorded.
Legal action will be taken. Please disconnect now.
" > /etc/issue
echo "
Unauthorized access to this server is prohibited.
All connections are monitored and recorded.
Legal action will be taken. Please disconnect now.
" > /etc/issue.net
}
install_lynis_recommended_packages() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs lynis recommended packages
apt install apt-listchanges needrestart debsecan debsums libpam-cracklib aide usbguard acct
}
move_/tmp_to_/tmpfs() {
# Moves /tmp to /tmpfs
echo "tmpfs /tmp tmpfs rw,nosuid,nodev" >> /etc/fstab
}
purge_old_removed_packages() {
# Purges old and removed packages
apt autoremove
apt purge "$(dpkg -l | grep '^rc' | awk '{print $2}')"
}
remount_directories_with_restrictions() {
# Mounts /proc with hidepid=2
mount -o remount,rw,hidepid=2 /proc
# Mounts /tmp with noexec
mount -o remount,noexec /tmp
# Mount /dev with noexec
mount -o remount,noexec /dev
# Mounts /run as nodev
mount -o remount,nodev /run
# Keeps /boot as read only
echo "LABEL=/boot /boot ext2 defaults,ro 1 2" >> /etc/fstab
}
restrict_access_to_compilers() {
# Restricts access to compilers
v=$(which clang)
d=$(which gcc)
f=$(which c++)
h=$(which clang++)
r=$(which g++)
length=${#v}
lengt=${#d}
leng=${#f}
len=${#h}
le=${#r}
if [ "$length" -gt 0 ]
then
chmod o-x "$v"
chmod o-r "$v"
chmod o-w "$v"
fi
if [ "$lengt" -gt 0 ]
then
chmod o-x "$d"
chmod o-r "$d"
chmod o-w "$d"
fi
if [ "$leng" -gt 0 ]
then
chmod o-x "$f"
chmod o-r "$f"
chmod o-w "$f"
fi
if [ "$len" -gt 0 ]
then
chmod o-x "$h"
chmod o-r "$h"
chmod o-w "$h"
fi
if [ "$le" -gt 0 ]
then
chmod o-x "$r"
chmod o-r "$r"
chmod o-w "$r"
fi
if [ -d "/usr/bin/as" ]
then
chmod o-x /usr/bin/as
chmod o-r /usr/bin/as
chmod o-w /usr/bin/as
fi
}
restrict_logins() {
# Restricts logins by configuring login.defs
sed -i s/PASS_MIN_DAYS.*/PASS_MIN_DAYS\ 7/ /etc/login.defs
sed -i s/UMASK.*/UMASK\ 027/ /etc/login.defs
sed -i s/PASS_MAX_DAYS.*/PASS_MAX_DAYS\ 30/ /etc/login.defs
echo "SHA_CRYPT_MIN_ROUNDS 1000000
SHA_CRYPT_MAX_ROUNDS 100000000" >> /etc/login.defs
# Locks all empty password accounts
v=$(awk -F: '($2 == "") {print}' /etc/shadow)
d=length=${#v}
if [ "$d" -gt 0 ]
then
for i in $v
do
passwd -l "$i"
done
fi
}
secure_ssh() {
# Secures ssh
if [ "$qw" == "y" ]
then
echo "
ClientAliveCountMax 2
ClientAliveInterval 300
Compression no
LogLevel VERBOSE
MaxAuthTries 3
MaxSessions 2
TCPKeepAlive no
AllowAgentForwarding no
AllowTcpForwarding no
Port $ty
PasswordAuthentication no
AuthenticationMethods publickey
PubkeyAuthentication yes
ChallengeResponseAuthentication no
PermitEmptyPasswords no
HostbasedAuthentication no
IgnoreRhosts yes
Protocol 2
Ciphers aes128-ctr,aes192-ctr,aes256-ctr
X11Forwarding no
" >> /etc/ssh/sshd_config
sed -i s/^X11Forwarding.*/X11Forwarding\ no/ /etc/ssh/sshd_config
sed -i s/^UsePAM.*/UsePAM\ yes/ /etc/ssh/sshd_config
echo -n "Please enter the adminsters username:"
read -r e
echo "
AllowUsers $e
PermitRootLogin no
" >> /etc/ssh/sshd_config
fi
if [ "$qw" == "N" ]
then
echo "
ClientAliveCountMax 2
ClientAliveInterval 300
Compression no
LogLevel VERBOSE
MaxAuthTries 3
MaxSessions 2
TCPKeepAlive no
AllowAgentForwarding no
AllowTcpForwarding no
Port 22
PasswordAuthentication no
AuthenticationMethods publickey
PubkeyAuthentication yes
ChallengeResponseAuthentication no
PermitEmptyPasswords no
HostbasedAuthentication no
IgnoreRhosts yes
Protocol 2
Ciphers aes128-ctr,aes192-ctr,aes256-ctr
" >> /etc/ssh/sshd_config
sed -i s/^X11Forwarding.*/X11Forwarding\ no/ /etc/ssh/sshd_config
sed -i s/^UsePAM.*/UsePAM\ yes/ /etc/ssh/sshd_config
echo -n "Please enter the adminstrators username: "
read -r e
echo "
AllowUsers $e
PermitRootLogin no
" >> /etc/ssh/sshd_config
fi
}
setup_aide() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs and sets up aide
apt install aide
aideinit
cp /var/lib/aide/aide.db.new /var/lib/aide/aide.db
update-aide.conf
cp /var/lib/aide/aide.conf.autogenerated /etc/aide/aide.conf
}
update_upgrade() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Updates the package list
apt update
# Upgrades packages
apt upgrade
# Does a dist upgrade, which "intelligently" handles changing dependencies
apt dist-upgrade
}
setup_rkhunter_and_chkrootkit() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs chkrootkit
apt install chkrootkit
# Installs rkhunter
apt install rkhunter
# You need to specify where both softwares should look for the commands they require to run scans to detect rootkits
chkrootkit -p /mnt/safe
rkhunter --check --bindir /mnt/safe
}
disable_thunderbolt() {
# Disables Thunderbolt
echo "blacklist thunderbolt" >> /etc/modprobe.d/thunderbolt.conf
}
setup_psad() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs psad
apt install psad
# Sets up psad
echo -e "kern.info\t|/var/lib/psad/psadfifo" >> /etc/syslog.conf
/etc/init.d/sysklogd restart
/etc/init.d/klogd
echo -n "Please enter your email address to receive port scan detection messages:"
read -r la
echo -e "EMAIL_ADDRESSES $la;
ENABLE_AUTO_IDS Y;
IPTABLES_BLOCK_METHOD Y;
HOME_NET NOT_USED;
" >> /etc/psad/psad.conf
# Automatically removes all blocked ip addresses
psad -F
# Restarts psad to save configuaration information
/etc/init.d/psad restart
}
protect_physical_console_access() {
# Create a grub boot loader password
openssl passwd -1
echo "Please copy down this password"
echo -n "Please enter the hashed password that you were just given:"
read -r lye
echo "password --md5 $lye" >> /boot/grub/menu.lst
# Enables authentication for single-user mode
echo "~~:S:wait:/sbin/sulogin" >> /etc/inittab
# Disables interactive hotkey startup at boot
echo "PROMPT=no" >> /etc/sysconfig/init
# Automatically logsout Bash users
echo "
TMOUT=300
readonly TMOUT
export TMOUT" >> /etc/profile.d/autologout.sh
chmod +x /etc/profile.d/autologout.sh
# Disable Ctrl-Alt-Delete
sed -e '/ca::ctrlaltdel:/sbin/shutdown -t3 -r now/ s/^#*/#/' -i /etc/inittab
init q
sed -e '/exec /sbin/shutdown -r now "Control-Alt-Delete pressed"/ s/^#*/#/' -i /etc/event.d/control-alt-delete
# Configures root user timeout
echo "[ $UID -eq 0 ] && TMOUT=300" >> /etc/profiles
}
setup_lighttpd() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs lighttpd
apt install lighttpd
# Sets up lighttpd
echo "server.kbytes-per-second=1024" >> lighttpd.conf
service lighttpd reload
echo "connection.kbytes-per-second=64" >> lighttpd.conf
service lighttpd reload
}
setup_shorewall() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs shorewall
apt install shorewall shorewall-common shorewall-shell
# Sets up shorewall
echo "startup=1" >> /etc/default/shorewall
echo "#ZONE TYPE OPTIONS IN OUT
# OPTIONS OPTIONS
fw firewall
net ipv4" >> /etc/shorewall/zones
echo "#ZONE INTERFACE BROADCAST OPTIONS
net eth0 detect tcpflags,logmartians,nosmurfs
net eth1 detect dhcp
net ppp+ detect dhcp" >> /etc/shorewall/interfaces
echo "#SOURCE DEST POLICY LOG LEVEL LIMIT:
BURST
fw all ACCEPT
net all DROP info
all all REJECT info" >> /etc/shorewall/policy
}
install_logwatch() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs logcheck
apt install logwatch
}
setup_ufw() {
# Cleans out the local repository of retrieved package files that are left in /var/cache
apt clean
# Installs ufw
apt install ufw
# Sets up ufw
ufw default deny incoming
ufw default allow outgoing
ufw logging on
ufw deny 20/tcp
ufw deny 21/tcp
ufw deny 23/tcp
ufw deny 69/udp
ufw deny 110/tcp
ufw deny 143/tcp
ufw deny 161/udp