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Lynis : Security Audit
2021/09/29
 
Install Lynis which is the Security Audit Tool.
[1] Install Lynis.
root@dlp:~#
apt -y install lynis
[2] This is the Basic usage of Lynis.
# run like follows for initial scanning

root@dlp:~#
lynis audit system


[ Lynis 3.0.2 ]

################################################################################
  Lynis comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
  welcome to redistribute it under the terms of the GNU General Public License.
  See the LICENSE file for details about using this software.

  2007-2020, CISOfy - https://cisofy.com/lynis/
  Enterprise support available (compliance, plugins, interface and tools)
################################################################################


[+] Initializing program
------------------------------------
  - Detecting OS...                                           [ DONE ]
  - Checking profiles...                                      [ DONE ]

  ---------------------------------------------------
  Program version:           3.0.2
  Operating system:          Linux
  Operating system name:     Debian
  Operating system version:  11.0
  Kernel version:            5.10.0
  Hardware platform:         x86_64
  Hostname:                  dlp
  ---------------------------------------------------
  Profiles:                  /etc/lynis/default.prf
  Log file:                  /var/log/lynis.log
  Report file:               /var/log/lynis-report.dat
  Report version:            1.0
  Plugin directory:          /etc/lynis/plugins
  ---------------------------------------------------
  Auditor:                   [Not Specified]
  Language:                  en
  Test category:             all
  Test group:                all
  ---------------------------------------------------
  - Program update status...                                  [ NO UPDATE ]

.....
.....

================================================================================

  Lynis security scan details:

  Hardening index : 62 [############        ]
  Tests performed : 240
  Plugins enabled : 1

  Components:
  - Firewall               [V]
  - Malware scanner        [X]

  Scan mode:
  Normal [V]  Forensics [ ]  Integration [ ]  Pentest [ ]

  Lynis modules:
  - Compliance status      [?]
  - Security audit         [V]
  - Vulnerability scan     [V]

  Files:
  - Test and debug information      : /var/log/lynis.log
  - Report data                     : /var/log/lynis-report.dat

================================================================================

  Lynis 3.0.2

  Auditing, system hardening, and compliance for UNIX-based systems
  (Linux, macOS, BSD, and others)

  2007-2020, CISOfy - https://cisofy.com/lynis/
  Enterprise support available (compliance, plugins, interface and tools)

================================================================================

  [TIP]: Enhance Lynis audits by adding your settings to custom.prf (see /etc/lynis/default.prf for all settings)
[3] The report of scanning result is saved on [/var/log/lynis-report.dat].
Search the file with words [warning] or [suggestion], then it shows recommended settings like follows.
root@dlp:~#
grep -E "^warning|^suggestion" /var/log/lynis-report.dat

suggestion[]=LYNIS|This release is more than 4 months old. Check the website or GitHub to see if there is an update available.|-|-|
suggestion[]=DEB-0280|Install libpam-tmpdir to set $TMP and $TMPDIR for PAM sessions|-|-|
suggestion[]=DEB-0810|Install apt-listbugs to display a list of critical bugs prior to each APT installation.|-|-|
suggestion[]=DEB-0831|Install needrestart, alternatively to debian-goodies, so that you can run needrestart after upgrades to determine which daemons are using old versions of libraries and need restarting.|-|-|
suggestion[]=DEB-0870|Install debsecan to generate lists of vulnerabilities which affect this installation.|-|-|
suggestion[]=DEB-0875|Install debsums for the verification of installed package files against MD5 checksums.|-|-|
suggestion[]=DEB-0880|Install fail2ban to automatically ban hosts that commit multiple authentication errors.|-|-|
suggestion[]=BOOT-5122|Set a password on GRUB boot loader to prevent altering boot configuration (e.g. boot in single user mode without password)|-|-|
suggestion[]=BOOT-5264|Consider hardening system services|Run '/usr/bin/systemd-analyze security SERVICE' for each service|-|
suggestion[]=KRNL-5788|Determine priority for available kernel update|-|-|
suggestion[]=KRNL-5820|If not required, consider explicit disabling of core dump in /etc/security/limits.conf file|-|-|
suggestion[]=PROC-3614|Check process listing for processes waiting for IO requests|-|-|
suggestion[]=AUTH-9230|Configure password hashing rounds in /etc/login.defs|-|-|
suggestion[]=AUTH-9262|Install a PAM module for password strength testing like pam_cracklib or pam_passwdqc|-|-|
suggestion[]=AUTH-9282|When possible set expire dates for all password protected accounts|-|-|
suggestion[]=AUTH-9286|Configure minimum password age in /etc/login.defs|-|-|
suggestion[]=AUTH-9286|Configure maximum password age in /etc/login.defs|-|-|
suggestion[]=AUTH-9328|Default umask in /etc/login.defs could be more strict like 027|-|-|
suggestion[]=FILE-6310|To decrease the impact of a full /home file system, place /home on a separate partition|-|-|
suggestion[]=FILE-6310|To decrease the impact of a full /tmp file system, place /tmp on a separate partition|-|-|
suggestion[]=FILE-6310|To decrease the impact of a full /var file system, place /var on a separate partition|-|-|
suggestion[]=FILE-6430|Consider disabling unused kernel modules|/etc/modprobe.d/blacklist.conf|Add 'install MODULENAME /bin/true' (without quotes)|
suggestion[]=USB-1000|Disable drivers like USB storage when not used, to prevent unauthorized storage or data theft|-|-|
suggestion[]=STRG-1846|Disable drivers like firewire storage when not used, to prevent unauthorized storage or data theft|-|-|
suggestion[]=NAME-4404|Add the IP name and FQDN to /etc/hosts for proper name resolving|-|-|
suggestion[]=PKGS-7346|Purge old/removed packages (1 found) with aptitude purge or dpkg --purge command. This will cleanup old configuration files, cron jobs and startup scripts.|-|-|
suggestion[]=PKGS-7370|Install debsums utility for the verification of packages with known good database.|-|-|
warning[]=PKGS-7392|Found one or more vulnerable packages.|-|-|
suggestion[]=PKGS-7392|Update your system with apt-get update, apt-get upgrade, apt-get dist-upgrade and/or unattended-upgrades|-|-|
suggestion[]=PKGS-7420|Consider using a tool to automatically apply upgrades|-|-|
warning[]=NETW-2705|Couldn't find 2 responsive nameservers|-|-|
suggestion[]=NETW-2705|Check your resolv.conf file and fill in a backup nameserver if possible|-|-|
suggestion[]=NETW-3200|Determine if protocol 'dccp' is really needed on this system|-|-|
suggestion[]=NETW-3200|Determine if protocol 'sctp' is really needed on this system|-|-|
suggestion[]=NETW-3200|Determine if protocol 'rds' is really needed on this system|-|-|
suggestion[]=NETW-3200|Determine if protocol 'tipc' is really needed on this system|-|-|
suggestion[]=LOGG-2154|Enable logging to an external logging host for archiving purposes and additional protection|-|-|
suggestion[]=BANN-7126|Add a legal banner to /etc/issue, to warn unauthorized users|-|-|
suggestion[]=BANN-7130|Add legal banner to /etc/issue.net, to warn unauthorized users|-|-|
suggestion[]=ACCT-9622|Enable process accounting|-|-|
suggestion[]=ACCT-9626|Enable sysstat to collect accounting (no results)|-|-|
suggestion[]=ACCT-9628|Enable auditd to collect audit information|-|-|
suggestion[]=FINT-4350|Install a file integrity tool to monitor changes to critical and sensitive files|-|-|
suggestion[]=TOOL-5002|Determine if automation tools are present for system management|-|-|
suggestion[]=FILE-7524|Consider restricting file permissions|See screen output or log file|text:Use chmod to change file permissions|
suggestion[]=HOME-9304|Double check the permissions of home directories as some might be not strict enough.|-|-|
suggestion[]=KRNL-6000|One or more sysctl values differ from the scan profile and could be tweaked||Change sysctl value or disable test (skip-test=KRNL-6000:<sysctl-key>)|
suggestion[]=HRDN-7230|Harden the system by installing at least one malware scanner, to perform periodic file system scans|-|Install a tool like rkhunter, chkrootkit, OSSEC|
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