Linux Auditd Best Practice Configuration

audit.rules

# Linux Audit Daemon - Best Practice Configuration 
# /etc/audit/audit.rules
# 
# Based on rules published here:
# Gov.uk auditd rules
# https://github.com/gds-operations/puppet-auditd/pull/1
# CentOS 7 hardening
# https://highon.coffee/blog/security-harden-centos-7/#auditd---audit-daemon
# Linux audit repo 
# https://github.com/linux-audit/audit-userspace/tree/master/rules
# Auditd high performance linux auditing
# https://linux-audit.com/tuning-auditd-high-performance-linux-auditing/
#
# Further rules
# For PCI DSS compliance see: 
# https://github.com/linux-audit/audit-userspace/blob/master/rules/30-pci-dss-v31.rules
# For NISPOM compliance see:
# https://github.com/linux-audit/audit-userspace/blob/master/rules/30-nispom.rules
#
# Compiled by Florian Roth
# 2017/12/05

# Remove any existing rules
-D

# Buffer Size
## Feel free to increase this if the machine panic's
-b 8192

# Failure Mode
## Possible values: 0 (silent), 1 (printk, print a failure message), 2 (panic, halt the system)
-f 1

# Ignore errors
## e.g. caused by users or files not found in the local environment  
-i 

# Self Auditing ---------------------------------------------------------------

# Audit the audit logs
## Successful and unsuccessful attempts to read information from the audit records
-w /var/log/audit/ -k auditlog

# Auditd configuration
## Modifications to audit configuration that occur while the audit collection functions are operating
-w /etc/audit/ -p wa -k auditconfig
-w /etc/libaudit.conf -p wa -k auditconfig
-w /etc/audisp/ -p wa -k audispconfig

# Monitor for use of audit management tools
-w /sbin/auditctl -p x -k audittools
-w /sbin/auditd -p x -k audittools

# Filters ---------------------------------------------------------------------

# This is for don't audit rules. We put these early because audit
# is a first match wins system.

# Cron jobs fill the logs with stuff we normally don't want
-a never,user -F subj_type=crond_t

# This 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

# This is not very interesting and wastes a lot of space if the server is public facing
-a always,exclude -F msgtype=CRYPTO_KEY_USER

# 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

# More information on how to filter events
# https://access.redhat.com/solutions/2482221

# Rules -----------------------------------------------------------------------

# Kernel parameters
-w /etc/sysctl.conf -p wa -k sysctl

# Kernel module loading and unloading
-w /sbin/insmod -p x -k modules
-w /sbin/rmmod -p x -k modules
-w /sbin/modprobe -p x -k modules
-a always,exit -F arch=b64 -S init_module -S delete_module -k modules
# Modprobe configuration
-w /etc/modprobe.conf -p wa -k modprobe

# 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 exit,always -F arch=b32 -S mount -S umount -S umount2 -k mount
-a exit,always -F arch=b64 -S mount -S umount2 -k mount

# 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
## Local time zone
-w /etc/localtime -p wa -k localtime

# Stunnel
-w /usr/sbin/stunnel -p x -k stunnel

# Cron configuration & scheduled jobs
-w /etc/cron.allow -p wa -k cron
-w /etc/cron.deny -p wa -k cron
-w /etc/cron.d/ -p wa -k cron
-w /etc/cron.daily/ -p wa -k cron
-w /etc/cron.hourly/ -p wa -k cron
-w /etc/cron.monthly/ -p wa -k cron
-w /etc/cron.weekly/ -p wa -k cron
-w /etc/crontab -p wa -k cron
-w /var/spool/cron/crontabs/ -k cron

# User, group, 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

# Sudoers file changes
-w /etc/sudoers -p wa -k actions

# Passwd
-w /usr/bin/passwd -p x -k passwd_modification

# Tools to change group identifiers
-w /usr/sbin/groupadd -p x -k group_modification
-w /usr/sbin/groupmod -p x -k group_modification
-w /usr/sbin/addgroup -p x -k group_modification
-w /usr/sbin/useradd -p x -k user_modification
-w /usr/sbin/usermod -p x -k user_modification
-w /usr/sbin/adduser -p x -k user_modification

# 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
## Changes to 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
## Changes to other files
-w /etc/hosts -p wa -k network_modifications
-w /etc/sysconfig/network -p wa -k network_modifications
-w /etc/network/ -p wa -k network
-a always,exit -F dir=/etc/NetworkManager/ -F perm=wa -k network_modifications
-w /etc/sysconfig/network -p wa -k network_modifications
## Changes to issue
-w /etc/issue -p wa -k etcissue
-w /etc/issue.net -p wa -k etcissue

# System startup scripts
-w /etc/inittab -p wa -k init
-w /etc/init.d/ -p wa -k init
-w /etc/init/ -p wa -k init

# Library search paths
-w /etc/ld.so.conf -p wa -k libpath

# Pam configuration
-w /etc/pam.d/ -p wa -k pam
-w /etc/security/limits.conf -p wa  -k pam
-w /etc/security/pam_env.conf -p wa -k pam
-w /etc/security/namespace.conf -p wa -k pam
-w /etc/security/namespace.init -p wa -k pam

# GDS specific secrets
-w /etc/puppet/ssl -p wa -k puppet_ssl

# Postfix configuration
-w /etc/aliases -p wa -k mail
-w /etc/postfix/ -p wa -k mail

# SSH configuration
-w /etc/ssh/sshd_config -k sshd

# SELinux events that modify the system's Mandatory Access Controls (MAC)
-w /etc/selinux/ -p wa -k mac_policy

# Critical elements access failures 
-a exit,always -F arch=b64 -S open -F dir=/etc -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=/sbin -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=/usr/sbin -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=/home -F success=0 -k unauthedfileacess
-a exit,always -F arch=b64 -S open -F dir=/srv -F success=0 -k unauthedfileacess

# Process ID change (switching accounts) 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

# Power state
-w /sbin/shutdown -p x -k power
-w /sbin/poweroff -p x -k power
-w /sbin/reboot -p x -k power
-w /sbin/halt -p x -k power

# 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

# Special Rules ---------------------------------------------------------------

# 32bit API Exploitation
## If you are on a 64 bit platform, everything _should_ be running
## in 64 bit mode. This rule will detect any use of the 32 bit syscalls
## because this might be a sign of someone exploiting a hole in the 32
## bit API.
-a always,exit -F arch=b32 -S all -k 32bit_api

# Injection 
## These rules watch for code injection by the ptrace facility.
## This could indicate someone trying to do something bad 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 dir.
-a always,exit -F dir=/home -F uid=0 -F auid>=1000 -F auid!=4294967295 -C auid!=obj_uid -k power_abuse

# High volume events ----------------------------------------------------------

# 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

# 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

# File Access
## Unauthorized Access (unsuccessful)
-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

## 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

# Make the configuration immutable --------------------------------------------
#-e 2