CIS® (Center for Internet Security, Inc.) is a forward-thinking, non-profit entity that harnesses the power of a global IT community to safeguard private and public organizations against cyber threats.
The CIS Controls™ and CIS Benchmarks™ are the global standard and recognized best practices for securing IT systems and data against the most pervasive attacks. These proven guidelines are continuously refined and verified by a volunteer, global community of experienced IT professionals.
Over time we have seen more and more customers asking for CIS hardening details on the Snare v8 install. The v7 of Snare Central used STIG and some CIS technical controls. For v8 of Snare Central it now has full coverage of the CIS controls which extended the STIG technical controls. The cisecurity.org site provides a multitude of security review and hardening build standards for many operating systems.
The CIS Benchmark for Ubuntu Linux provides prescriptive guidance for establishing a secure configuration posture for Ubuntu Linux 18.04 LTS systems running on x86 and x64 platforms. Many lists include filesystem types, services, clients, and network protocols. Not all items in these lists are guaranteed to exist on all distributions and additional similar items may exist which should be considered in addition to those explicitly mentioned. The full document can be reviewed ont he cisecurity.org site.
Note
CIS requires auditd to be enabled in the system for it to be compliant. Snare Central enables the auditing system only when STIG compliance is enabled, hence it is required that STIG be enabled for the Snare Central to be fully CIS compliant.
We used Nessus vulnerability scanner for a CIS compliance assessment on Snare Central. The following table lists all Nessus benchmark items that are assessed:
| chapter | section | index | title | v8.x.x enabled |
| 1 | Initial Setup | |||
| 1.1 | Filesystem Configuration | |||
| 1.1.1.1 | Ensure mounting of cramfs filesystems is disabled | always | ||
| 1.1.1.2 | Ensure mounting of freevxfs filesystems is disabled | always | ||
| 1.1.1.3 | Ensure mounting of jffs2 filesystems is disabled | always | ||
| 1.1.1.4 | Ensure mounting of hfs filesystems is disabled | always | ||
| 1.1.1.5 | Ensure mounting of hfsplus filesystems is disabled | always | ||
| 1.1.1.6 | Ensure mounting of udf filesystems is disabled | always | ||
| 1.1.2 | Ensure separate partition exists for /tmp | always | ||
| 1.1.3 | Ensure nodev option set on /tmp partition | always | ||
| 1.1.4 | Ensure nosuid option set on /tmp partition | always | ||
| 1.1.5 | Ensure separate partition exists for /var | always | ||
| 1.1.6 | Ensure separate partition exists for /var/tmp | always | ||
| 1.1.7 | Ensure nodev option set on /var/tmp partition | always | ||
| 1.1.8 | Ensure nosuid option set on /var/tmp partition | always | ||
| 1.1.9 | Ensure noexec option set on /var/tmp partition | always | ||
| 1.1.10 | Ensure separate partition exists for /var/log | always | ||
| 1.1.11 | Ensure separate partition exists for /var/log/audit | always | ||
| 1.1.12 | Ensure separate partition exists for /home | always | ||
| 1.1.13 | Ensure nodev option set on /home partition | always | ||
| 1.1.14 | Ensure nodev option set on /dev/shm partition (/run) | always | ||
| 1.1.15 | Ensure nosuid option set on /dev/shm partition (/run) | always | ||
| 1.1.16 | Ensure noexec option set on /dev/shm partition (/run) | always | ||
| 1.1.17 | Ensure nodev option set on removable media partitions | always | ||
| 1.1.18 | Ensure nosuid option set on removable media partitions | always | ||
| 1.1.19 | Ensure noexec option set on removable media partitions | always | ||
| 1.1.20 | Ensure sticky bit is set on all world-writable directories | always | ||
| 1.1.21 | Disable Automounting | always | ||
| 1.2 | Configure Software Updates | |||
| 1.2.1 | Ensure package manager repositories are configured | always | ||
| 1.2.2 | Ensure GPG keys are configured | always | ||
| 1.3 | Filesystem Integrity Checking | |||
| 1.3.1 | Ensure AIDE is installed | always | ||
| 1.3.2 | Ensure filesystem integrity is regularly checked | always | ||
| 1.4 | Secure Boot Settings | |||
| 1.4.1 | Ensure permissions on bootloader config are configured | always | ||
| 1.4.2 | Ensure bootloader password is set | Won't do | ||
| 1.4.3 | Ensure authentication required for single user mode | always | ||
| 1.5 | Additional Process Hardening | |||
| 1.5.1 | Ensure core dumps are restricted | always | ||
| 1.5.2 | Ensure XD/NX support is enabled | always | ||
| 1.5.3 | Ensure address space layout randomization (ASLR) is enabled | always | ||
| 1.5.4 | Ensure prelink is disabled | always | ||
| 1.6 | Mandatory Access Control | |||
| 1.6.1.1 | Ensure SELinux is not disabled in bootloader configuration | always | ||
| 1.6.1.2 | Ensure the SELinux state is enforcing | always | ||
| 1.6.1.3 | Ensure SELinux policy is configured | always | ||
| 1.6.1.4 | Ensure no unconfined daemons exist | always | ||
| 1.6.2.1 | Ensure AppArmor is not disabled in bootloader configuration | always | ||
| 1.6.2.2 | Ensure all AppArmor Profiles are enforcing | always | ||
| 1.6.3 | Ensure SELinux or AppArmor are installed | always | ||
| 1.7 | Warning Banners | |||
| 1.7.1.1 | Ensure message of the day is configured properly | always | ||
| 1.7.1.2 | Ensure local login warning banner is configured properly | always | ||
| 1.7.1.3 | Ensure remote login warning banner is configured properly | always | ||
| 1.7.1.4 | Ensure permissions on /etc/motd are configured | always | ||
| 1.7.1.5 | Ensure permissions on /etc/issue are configured | always | ||
| 1.7.1.6 | Ensure permissions on /etc/issue.net are configured | always | ||
| 1.7.2 | Ensure GDM login banner is configured | always | ||
| 1.8 | Ensure updates patches and additional security software are installed | |||
| 2 | Services | |||
| 2.1 | inetd Services | |||
| 2.1.1 | Ensure chargen services are not enabled | always | ||
| 2.1.2 | Ensure daytime services are not enabled | always | ||
| 2.1.3 | Ensure discard services are not enabled | always | ||
| 2.1.4 | Ensure echo services are not enabled | always | ||
| 2.1.5 | Ensure time services are not enabled | always | ||
| 2.1.6 | Ensure rsh server is not enabled | always | ||
| 2.1.7 | Ensure talk server is not enabled | always | ||
| 2.1.8 | Ensure telnet server is not enabled | always | ||
| 2.1.9 | Ensure tftp server is not enabled | always | ||
| 2.1.10 | Ensure xinetd is not enabled | always | ||
| 2.1.11 | Ensure openbsd-inetd is not installed | always | ||
| 2.2 | Special Purpose Services | |||
| 2.2.1.1 | Ensure time synchronization is in use | false positive | ||
| 2.2.1.2 | Ensure ntp is configured | always | ||
| 2.2.1.3 | Ensure chrony is configured | false positive | ||
| 2.2.2 | Ensure X Window System is not installed | always | ||
| 2.2.3 | Ensure Avahi Server is not enabled | always | ||
| 2.2.4 | Ensure CUPS is not enabled | always | ||
| 2.2.5 | Ensure DHCP Server is not enabled | always | ||
| 2.2.6 | Ensure LDAP server is not enabled | always | ||
| 2.2.7 | Ensure NFS and RPC are not enabled | false positive | ||
| 2.2.8 | Ensure DNS Server is not enabled | always | ||
| 2.2.9 | Ensure FTP Server is not enabled | always | ||
| 2.2.10 | Ensure HTTP server is not enabled | won't fix | ||
| 2.2.11 | Ensure IMAP and POP3 server is not enabled | always | ||
| 2.2.12 | Ensure Samba is not enabled | false positive | ||
| 2.2.13 | Ensure HTTP Proxy Server is not enabled | always | ||
| 2.2.14 | Ensure SNMP Server is not enabled | false positive | ||
| 2.2.15 | Ensure mail transfer agent is configured for local-only mode | always | ||
| 2.2.16 | Ensure rsync service is not enabled | false positive | ||
| 2.2.17 | Ensure NIS Server is not enabled | always | ||
| 2.3 | Service Clients | |||
| 2.3.1 | Ensure NIS Client is not installed | always | ||
| 2.3.2 | Ensure rsh client is not installed | always | ||
| 2.3.3 | Ensure talk client is not installed | always | ||
| 2.3.4 | Ensure telnet client is not installed | always | ||
| 2.3.5 | Ensure LDAP client is not installed | false positive | ||
| 3 | Network Configuration | |||
| 3.1 | Network Parameters (Host Only) | |||
| 3.1.1 | Ensure IP forwarding is disabled | always | ||
| 3.1.2 | Ensure packet redirect sending is disabled | always | ||
| 3.2 | Network Parameters (Host and Router) | |||
| 3.2.1 | Ensure source routed packets are not accepted | always | ||
| 3.2.2 | Ensure ICMP redirects are not accepted | always | ||
| 3.2.3 | Ensure secure ICMP redirects are not accepted | always | ||
| 3.2.4 | Ensure suspicious packets are logged | always | ||
| 3.2.5 | Ensure broadcast ICMP requests are ignored | always | ||
| 3.2.6 | Ensure bogus ICMP responses are ignored | always | ||
| 3.2.7 | Ensure Reverse Path Filtering is enabled | always | ||
| 3.2.8 | Ensure TCP SYN Cookies is enabled | always | ||
| 3.3 | Ipv6 | |||
| 3.3.1 | Ensure IPv6 router advertisements are not accepted | always | ||
| 3.3.2 | Ensure IPv6 redirects are not accepted | always | ||
| 3.3.3 | Ensure IPv6 is disabled | always | ||
| 3.4 | TCP Wrappers | |||
| 3.4.1 | Ensure TCP Wrappers is installed | always | ||
| 3.4.2 | Ensure /etc/hosts.allow is configured | false positive | ||
| 3.4.3 | Ensure /etc/hosts.deny is configured | false positive | ||
| 3.4.4 | Ensure permissions on /etc/hosts.allow are configured | always | ||
| 3.4.5 | Ensure permissions on /etc/hosts.deny are configured | always | ||
| 3.5 | Uncommon Network Protocols | |||
| 3.5.1 | Ensure DCCP is disabled | always | ||
| 3.5.2 | Ensure SCTP is disabled | always | ||
| 3.5.3 | Ensure RDS is disabled | always | ||
| 3.5.4 | Ensure TIPC is disabled | always | ||
| 3.6 | Firewall Configuration | |||
| 3.6.1 | Ensure iptables is installed | always | ||
| 3.6.2 | Ensure default deny firewall policy | always | ||
| 3.6.3 | Ensure loopback traffic is configured | always | ||
| 3.6.4 | Ensure outbound and established connections are configured | always | ||
| 3.6.5 | Ensure firewall rules exist for all open ports | always | ||
| 3.7 | Ensure wireless interfaces are disabled | always | ||
| 4 | Logging and Auditing | |||
| 4.1 | Configure System Accounting (auditd) | |||
| 4.1.1.1 | Ensure audit log storage size is configured | always | ||
| 4.1.1.2 | Ensure system is disabled when audit logs are full | false positive | ||
| 4.1.1.3 | Ensure audit logs are not automatically deleted | false positive | ||
| 4.1.2 | Ensure auditd service is enabled | needs STIG | ||
| 4.1.3 | Ensure auditing for processes that start prior to auditd is enabled | needs STIG | ||
| 4.1.4 | Ensure events that modify date and time information are collected | needs STIG | ||
| 4.1.5 | Ensure events that modify user/group information are collected | needs STIG | ||
| 4.1.6 | Ensure events that modify the system's network environment are collected | needs STIG | ||
| 4.1.7 | Ensure events that modify the system's Mandatory Access Controls are collected | needs STIG | ||
| 4.1.8 | Ensure login and logout events are collected | needs STIG | ||
| 4.1.9 | Ensure session initiation information is collected | needs STIG | ||
| 4.1.10 | Ensure discretionary access control permission modification events are collected | needs STIG | ||
| 4.1.11 | Ensure unsuccessful unauthorized file access attempts are collected | needs STIG | ||
| 4.1.12 | Ensure use of privileged commands is collected | needs STIG | ||
| 4.1.13 | Ensure successful file system mounts are collected | needs STIG | ||
| 4.1.14 | Ensure file deletion events by users are collected | needs STIG | ||
| 4.1.15 | Ensure changes to system administration scope (sudoers) is collected | needs STIG | ||
| 4.1.16 | Ensure system administrator actions (sudolog) are collected | needs STIG | ||
| 4.1.17 | Ensure kernel module loading and unloading is collected | needs STIG | ||
| 4.1.18 | Ensure the audit configuration is immutable | needs STIG | ||
| 4.2 | Configure Logging | |||
| 4.2.1.1 | Ensure rsyslog Service is enabled | always | ||
| 4.2.1.2 | Ensure logging is configured | always | ||
| 4.2.1.3 | Ensure rsyslog default file permissions configured | always | ||
| 4.2.1.4 | Ensure rsyslog is configured to send logs to a remote log host | false positive | ||
| 4.2.1.5 | Ensure remote rsyslog messages are only accepted on designated log hosts | false positive | ||
| 4.2.2.1 | Ensure syslog-ng service is enabled | always | ||
| 4.2.2.2 | Ensure logging is configured | always | ||
| 4.2.2.3 | Ensure syslog-ng default file permissions configured | always | ||
| 4.2.2.4 | Ensure syslog-ng is configured to send logs to a remote log host | always | ||
| 4.2.2.5 | Ensure remote syslog-ng messages are only accepted on designated log hosts] | always | ||
| 4.2.3 | Ensure rsyslog or syslog-ng is installed | always | ||
| 4.2.4 | Ensure permissions on all logfiles are configured | always | ||
| 4.3 | Ensure logrotate is configured | always | ||
| 5 | Access, Authentication and Authorization | |||
| 5.1 | Configure cron | |||
| 5.1.1 | Ensure cron daemon is enabled | always | ||
| 5.1.2 | Ensure permissions on /etc/crontab are configured | always | ||
| 5.1.3 | Ensure permissions on /etc/cron.hourly are configured | always | ||
| 5.1.4 | Ensure permissions on /etc/cron.daily are configured | always | ||
| 5.1.5 | Ensure permissions on /etc/cron.weekly are configured | always | ||
| 5.1.6 | Ensure permissions on /etc/cron.monthly are configured | always | ||
| 5.1.7 | Ensure permissions on /etc/cron.d are configured | always | ||
| 5.1.8 | Ensure at/cron is restricted to authorized users | always | ||
| 5.2 | SSH Server Configuration | always | ||
| 5.2.1 | Ensure permissions on /etc/ssh/sshd_config are configured | always | ||
| 5.2.2 | Ensure SSH Protocol is set to 2 | always | ||
| 5.2.3 | Ensure SSH LogLevel is set to INFO | always | ||
| 5.2.4 | Ensure SSH X11 forwarding is disabled | always | ||
| 5.2.5 | Ensure SSH MaxAuthTries is set to 4 or less | always | ||
| 5.2.6 | Ensure SSH IgnoreRhosts is enabled | always | ||
| 5.2.7 | Ensure SSH HostbasedAuthentication is disabled | always | ||
| 5.2.8 | Ensure SSH root login is disabled | always | ||
| 5.2.9 | Ensure SSH PermitEmptyPasswords is disabled | always | ||
| 5.2.10 | Ensure SSH PermitUserEnvironment is disabled | always | ||
| 5.2.11 | Ensure only approved MAC algorithms are used | always | ||
| 5.2.12 | Ensure SSH Idle Timeout Interval is configured | always | ||
| 5.2.13 | Ensure SSH LoginGraceTime is set to one minute or less | always | ||
| 5.2.14 | Ensure SSH access is limited | always | ||
| 5.2.15 | Ensure SSH warning banner is configured | always | ||
| 5.3 | Configure PAM | |||
| 5.3.1 | Ensure password creation requirements are configured | false positive | ||
| 5.3.2 | Ensure lockout for failed password attempts is configured | always | ||
| 5.3.3 | Ensure password reuse is limited | always | ||
| 5.3.4 | Ensure password hashing algorithm is SHA-512 | always | ||
| 5.4 | User Accounts and Environment | |||
| 5.4.1.1 | Ensure password expiration is 365 days or less | always | ||
| 5.4.1.2 | Ensure minimum days between password changes is 7 or more | always | ||
| 5.4.1.3 | Ensure password expiration warning days is 7 or more | always | ||
| 5.4.1.4 | Ensure inactive password lock is 30 days or less | always | ||
| 5.4.1.5 | Ensure all users last password change date is in the past | always | ||
| 5.4.2 | Ensure system accounts are non-login | always | ||
| 5.4.3 | Ensure default group for the root account is GID 0 | always | ||
| 5.4.4 | Ensure default user umask is 027 or more restrictive | always | ||
| 5.4.5 | Ensure default user shell timeout is 900 seconds or less | always | ||
| 5.5 | Ensure root login is restricted to system console | always | ||
| 5.6 | Ensure access to the su command is restricted | always | ||
| 6 | System Maintenance | |||
| 6.1 | System File Permissions | |||
| 6.1.1 | Audit system file permissions | always | ||
| 6.1.2 | Ensure permissions on /etc/passwd are configured | always | ||
| 6.1.3 | Ensure permissions on /etc/shadow are configured | always | ||
| 6.1.4 | Ensure permissions on /etc/group are configured | always | ||
| 6.1.5 | Ensure permissions on /etc/gshadow are configured | always | ||
| 6.1.6 | Ensure permissions on /etc/passwd- are configured | always | ||
| 6.1.7 | Ensure permissions on /etc/shadow- are configured | always | ||
| 6.1.8 | Ensure permissions on /etc/group- are configured | always | ||
| 6.1.9 | Ensure permissions on /etc/gshadow- are configured | always | ||
| 6.1.10 | Ensure no world writable files exist | false positive | ||
| 6.1.11 | Ensure no unowned files or directories exist | always | ||
| 6.1.12 | Ensure no ungrouped files or directories exist | always | ||
| 6.1.13 | Audit SUID executables | always | ||
| 6.1.14 | Audit SGID executables | always | ||
| 6.2 | User and Group Settings | |||
| 6.2.1 | Ensure password fields are not empty | always | ||
| 6.2.2 | Ensure no legacy "+" entries exist in /etc/passwd | always | ||
| 6.2.3 | Ensure no legacy "+" entries exist in /etc/shadow | always | ||
| 6.2.4 | Ensure no legacy "+" entries exist in /etc/group | always | ||
| 6.2.5 | Ensure root is the only UID 0 account | always | ||
| 6.2.6 | Ensure root PATH Integrity | always | ||
| 6.2.7 | Ensure all users' home directories exist | always | ||
| 6.2.8 | Ensure users' home directories permissions are 750 or more restrictive | always | ||
| 6.2.9 | Ensure users own their home directories | always | ||
| 6.2.10 | Ensure users' dot files are not group or world writable | always | ||
| 6.2.11 | Ensure no users have .forward files | always | ||
| 6.2.12 | Ensure no users have .netrc files | always | ||
| 6.2.13 | Ensure users' .netrc Files are not group or world accessible | always | ||
| 6.2.14 | Ensure no users have .rhosts files | always | ||
| 6.2.15 | Ensure all groups in /etc/passwd exist in /etc/group | always | ||
| 6.2.16 | Ensure no duplicate UIDs exist | always | ||
| 6.2.17 | Ensure no duplicate GIDs exist | always | ||
| 6.2.18 | Ensure no duplicate user names exist | always | ||
| 6.2.19 | Ensure no duplicate group names exist | always | ||
| 6.2.20 | Ensure shadow group is empty | always | ||
CIS vs STIG solved only conflict:
CIS recommendation 5.2.11 states that we need to "Ensure only approved MAC algorithms are used", however STIG V-23826 requires that the SSH daemon only uses a FIPS 140-2 validated cryptographic module (operating in FIPS mode). And after some research, this document: https://csrc.nist.gov/csrc/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp2907.pdf indicates that if we use the CIS settings for this parameter, we still satisfy the FIPS 140-2 validated cryptographic module and in consequence STIG V-23826 as well. MAC algorithms include:
hmac-sha2-512-etm@openssh.com,
hmac-sha2-256-etm@openssh.com,
umac-128-etm@openssh.com,
hmac-sha2-512,
hmac-sha2-256,
umac-128@openssh.com
False positives:
2.3.5 Ensure LDAP client is not installed. Snare Central comes with LDAP client.
2.2.1.1 Ensure time synchronization is in use. Snare Central runs ntpdate daily
2.2.1.3 Ensure chrony is configured. Snare Central does not use chrony
2.2.7 Ensure NFS and RPC are not enabled. User can disable NFS from UI
2.2.12 Ensure Samba is not enabled. User can disable samba from UI
2.2.14 Ensure SNMP Server is not enabled. User can disable SNMP from UI
2.2.16 Ensure rsync service is not enabled. Is used for side by side migration only.
3.4.2 Ensure /etc/hosts.allow is configured. The contents depend on user network layout.
3.4.3 Ensure /etc/hosts.deny is configured. The contents depend on user network layout.
4.1.1.2 Ensure system is disabled when audit logs are full. Snare Central uses SUSPEND instead of HALT
4.1.1.3 Ensure audit logs are not automatically deleted. Saner Central uses ROTATE instead of KEEP
4.2.1.4 Ensure rsyslog is configured to send logs to a remote log host. Not Applicable
4.2.1.5 Ensure remote rsyslog messages are only accepted on designated log hosts. Not Applicable
5.3.1 Ensure password creation requirements are configured. Saner Central uses pam_cracklib
6.1.10 Ensure no world writable files exist. Apache web server needs this file only: /tmp/perf-23853.map owner: www-data, group: www-data, permissions: 0666
Won't do:
1.4.2 Ensure bootloader password is set. this need to be done manually by the sysadmin