4 - Logging and Auditing#
4.1 - Configure auditd#
4.1.1 - Configure auditd#
Install auditd by running apt-get install auditd audispd-plugins.
Then enable the auditd service by running systemctl --now enable auditd.
Then open /etc/default/grub and add audit=1 and audit_backlog_limit=8192 to GRUB_CMDLINE_LINUX.
Ex:
GRUB_CMDLINE_LINUX="audit=1 audit_backlog_limit=8192"
Then run update-grub.
Multiple Parameters
Multiple parameters in GRUB_CMDLINE_LINUX should be separated by a space.
Ex: GRUB_CMDLINE_LINUX="audit=1 apparmor=1"
4.1.2 - Configure Data Retention#
Edit /etc/audit/auditd.conf to contain:
max_log_file = 6
max_log_file_action = keep_logs
space_left_action = email
action_mail_acct = root
admin_space_left_action = halt
4.1.3 - 4.1.16 - Configure logged events#
Create a file ending in .rules in /etc/audit/rules.d/ that contains:
On 32-bit systems:
-a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k time-
change
-a always,exit -F arch=b32 -S clock_settime -k time-change
-w /etc/localtime -p wa -k time-change
-w /etc/group -p wa -k identity
-w /etc/passwd -p wa -k identity
-w /etc/gshadow -p wa -k identity
-w /etc/shadow -p wa -k identity
-w /etc/security/opasswd -p wa -k identity
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/network -p wa -k system-locale
-w /etc/apparmor/ -p wa -k MAC-policy
-w /etc/apparmor.d/ -p wa -k MAC-policy
-w /var/log/faillog -p wa -k logins
-w /var/log/lastlog -p wa -k logins
-w /var/log/tallylog -p wa -k logins
-w /var/run/utmp -p wa -k session
-w /var/log/wtmp -p wa -k logins
-w /var/log/btmp -p wa -k logins
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F
auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F
auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S
removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295
-k perm_mod
-a always,exit -F arch=b32 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b32 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=4294967295 -k
mounts
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F
auid>=1000 -F auid!=4294967295 -k delete
-w /etc/sudoers -p wa -k scope
-w /etc/sudoers.d/ -p wa -k scope
-a exit,always -F arch=b32 -C euid!=uid -F euid=0 -Fauid>=1000 -F
auid!=4294967295 -S execve -k actions
-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=b32 -S init_module -S delete_module -k modules
On 64-bit systems:
-a always,exit -F arch=b64 -S adjtimex -S settimeofday -k time-change
-a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k time-
change
-a always,exit -F arch=b64 -S clock_settime -k time-change
-a always,exit -F arch=b32 -S clock_settime -k time-change
-w /etc/localtime -p wa -k time-change
-w /etc/group -p wa -k identity
-w /etc/passwd -p wa -k identity
-w /etc/gshadow -p wa -k identity
-w /etc/shadow -p wa -k identity
-w /etc/security/opasswd -p wa -k identity
-a always,exit -F arch=b64 -S sethostname -S setdomainname -k system-locale
-a always,exit -F arch=b32 -S sethostname -S setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/network -p wa -k system-locale
-w /etc/apparmor/ -p wa -k MAC-policy
-w /etc/apparmor.d/ -p wa -k MAC-policy
-w /var/log/faillog -p wa -k logins
-w /var/log/lastlog -p wa -k logins
-w /var/log/tallylog -p wa -k logins
-w /var/run/utmp -p wa -k session
-w /var/log/wtmp -p wa -k logins
-w /var/log/btmp -p wa -k logins
-a always,exit -F arch=b64 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F
auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F
auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S chown -S fchown -S fchownat -S lchown -F
auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F
auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S setxattr -S lsetxattr -S fsetxattr -S
removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295
-k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S
removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295
-k perm_mod
-a always,exit -F arch=b64 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b32 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b64 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b32 -S creat -S open -S openat -S truncate -S
ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=4294967295 -k access
-a always,exit -F arch=b64 -S mount -F auid>=1000 -F auid!=4294967295 -k
mounts
-a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=4294967295 -k
mounts
-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -F
auid>=1000 -F auid!=4294967295 -k delete
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F
auid>=1000 -F auid!=4294967295 -k delete
-w /etc/sudoers -p wa -k scope
-w /etc/sudoers.d/ -p wa -k scope
-a always,exit -F arch=b64 -C euid!=uid -F euid=0 -Fauid>=1000 -F
auid!=4294967295 -S execve -k actions
-a always,exit -F arch=b32 -C euid!=uid -F euid=0 -Fauid>=1000 -F
auid!=4294967295 -S execve -k actions
-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
Then add all lines resulting from the following command to another rules file.
find / -xdev \( -perm -4000 -o -perm -2000 \) -type f | awk '{print "-a
always,exit -F path=" $1 " -F perm=x -F auid>='"$(awk '/^\s*UID_MIN/{print
$2}' /etc/login.defs)"' -F auid!=4294967295 -k privileged" }' >>
/etc/audit/rules.d/50-privileged.rules
UID_MIN
The system may have a different UID_MIN, which can be checked by running awk '/^\s*UID_MIN/{print $2}' /etc/login.defs.
If the UID_MIN is not 1000, replace audit>=1000 in the above rules with audit>=YOUR_SYSTEM_UID_MIN.
4.1.17 - Ensure the audit configuration is immutable#
At the end of /etc/audit/rules.d/99-finalize.rules add
-e 2
4.2 - Configure logging#
4.2.1 - Configure rsyslog#
Install rsyslog by running sudo apt-get install rsyslog.
Enable the service by running systemctl --now enable rsyslog.
Run ls -l /var/log/ to make sure that the log files are functional.
In /etc/rsyslog.conf and /etc/rsyslog.d/*.conf, set all instances of $FileCreateMode to 0640.
(4.2.1.5 and 4.2.1.6 skipped)
4.2.2 - Configure journald#
In /etc/systemd/journald.conf add
ForwardToSyslog=yes
Compress=yes
Storage=persistent
4.2.3 - Ensure permissions on all logfiles are configured#
Set the permissions on all existing log files by running:
find /var/log -type f -exec chmod g-wx,o-rwx "{}" + -o -type d -exec chmod g-
w,o-rwx "{}" +
4.4 - Ensure logrotate assigns appropriate permissions#
In /etc/logrotate.conf change the create line to:
create 0640 root utmp