Any directive can be set and re-set with a customizable settings.ini for administering, tuning, and easier jail management. All existing entries in all confs will remain untouched unless they are modified in the settings file.
This script is also targeted to new users of GhostBSD so that they may leverage years of security contributions by the entire BSD community across all spectra, implemented on thier system in seconds.
Each of the security settings was researched, assessed, and chosen as a set of mitigations for maximizing threat reduction while minimizing restriction of system capability and availability.
- Firefox, Chromium explicity uses shared memory, conflicts with
kern.elf64.allow_wx - Linux Binary Compatability, nginx, VirtualBox shared folders, conflicts with
kern.securelevel
- Workstation: Librewolf, Evolution, RhythmBox, VLC, Abiword, Pluma, Gimp, Inkscape, Spacemacs, Git
- Server: Apache, OpenSMTPD, MariaDB
have_dynamic_loading=YES
- Desktop Wallpapers as a special gift to users of the Software
- Directory (Hier)archy Visual Map, PDF, in /docs
net.inet6.ip6.maxfrags = 0(*)- Official FreeBSD Security Advisory Workaround
- If using pf to scrub framents you do not need this workaround
- Add the directive above to
[SYSTEM} settings.iniif not using pf scrub, and until you can safely patch the system
- https://downfall.page/
- Computing devices based on Intel Core processors from the 6th Skylake to (including) the 11th Tiger Lake generation are affected.
- Vulnerability Checker
- Mitigation: Intel Microcode Update Expected
- ZenBleed Workaround with CPU microcode updating
- CPU microcode updating enabled in anticipation of Zenbleed and Downfall Patches
Full Changelog
- Scripts included to verify the implementation. Run before and after the repo Software.
- Kernel vulnerablity diagnosis provided by Stéphane Lesimple's spectre-meltdown-checker
chmod 750 spectre-meltdown-checker.sh- You should only be left with the MCEPSC, Machine Check Exception on Page Size Change Vulnerability, CVE-2018-12207
- MMAP, MProtect vulnerability diagnosis provided by u/zabolekar
cc mmap_protect.c./a.out- You should have two successes
- Kernel vulnerablity diagnosis provided by Stéphane Lesimple's spectre-meltdown-checker
- Overview
- Security Engineer's Discovery & Write-Up
- Affects AMD Zen 2 Chipset Family
- Mitigation/workaround suggested by discovering Security Engineer will not work in Virtual Machines
- AMD has patched the Rome family, server oriented series, of CPU's but all others are expected in December of 2023.
- The command to manually verify the chicken-bit has been set is
cpucontrol -m "0xc0011029" /dev/cpuctl0 - AMD Threadripper Pros are currently not being detected
- Sets the Model Specific Register chicken-bit exactly as suggested by the discovering Security Engineer
- Patches the latest AMD microcode from Platomov's GitHub Repository if available for your Zen2 CPU, currently, only "Rome" series as of August 11, 2023.
- If in a Virtual Machine, check for EPYC Rome series CPU and apply AMD patch and exit if not Rome, as there is no other patch available yet and Hypervisor disallows the workaround.
- Only if a Zenbleed vulnerable CPU is detected a CPU chicken-bit is be set every boot via a provided rc script
- Prompts to make a reminder to remove the script using
atto create a file calledREMINDER-AMD-Zenbleed-Removalin home directory on the 2023 December Solstice
chmod 750 zenbleed-workaround.cshsudo ./zenbleed-workaround.csh
./zenbleed-workaround.csh cleanremoves the CPU microcode/firmware utilities as a security measure once Zenbleed patching is complete- Do not use
cleanif you still need the workaround on baremetal as it uses cpucontrol.
- Do not use
./zenbleed-workaround.csh removeremoves the rc script for performance reasons or once the patch is applied from AMD in Decemeber 2023.- In the case of an AMD Zenbleed fully patched CPU, follow
removewithcleanfor security purposes.
- In the case of an AMD Zenbleed fully patched CPU, follow
- Makes backups of
rc.conf,sysctl.conf,login.conf, andloader.confon first run - Sets passwords to blowfish encryption
- Sets passwords to expire at 120 days
- Disables sendmail completely
- Removes
otherwrite permissions from key system files and folders - Allows only root for
cronandat - Primitive flag verification catches simple errors
- Modularizable within other tools
- Automate any shell script
- System Logging to
/var/log/messagesand Script Logging to/var/log/harden-freebsd.log - Pretty prints color output of script execution to console while running
- GhostBSD 23.06.01
- Python 3.9.16
WARNING: Once kernel level 1 is set by this script, you will not be able to modify these confs again with this script until it is set to -1 and rebooted!
- Set
kernlevel = -1if you want to test various setting groups with your applications and network - Customize
settings.inito whatever is needed, the script will change the directive to your flag - Set permissions
chmod 750 harden-ghostbsd.pyto prevent shell injection from another account or process - Set permissions
chmod 640 settings.inito prevent shell injection from another account or process - No
settings.inisection can be entirely commented out nor be completely empty sudo ./harden-ghostbsd.py
kern.vty = "vt"
This script does primitive verification of the confs flags in strict accordance with system man. Many online tutorials even on the FreeBSD family of websites do not use the proper syntax. Check the log for any validation failures. Use proper syntax, remove the syntax checking lines 241-261, or rewrite the regular expression to make a new check suitable for you.
- For
/etc/sysctl.confthe script checks for no quotes - For
/boot/loader.confthe script strictly verifies syntax from man and/boot/defaults/loader.confsyntax- All directives in these sister confs must be in quotes
If you do get stuck in read-only single-user mode and need to correct a configuration file then use:
zfs set readonly=off zroot
zfs mount -aMost tunable mitigations for 64bit are already included by default in GhostBSD 13.1 so 32bit directives were included for coverage. I can see no affect from setting the 32bit mitigations on 64bit systems, they are simply ignored. For clarity on unknown hardware, hardware mode, VM, or cloud use the following commands:
- CPU:
sysctl hw.model hw.machine hw.ncpu - Bits:
getconf LONG_BIT
The very first time the script is run it will make copies of rc.conf, sysctl.conf, login.conf, and loader.conf named rc.conf.original etc. If you've already done this yourself you may want to rename or move those files.
If you would like you can set settings.ini section [SCRIPT]option first_run to True with capital T to make new backups at any time after you've renamed the original backups or the script will overwrite them.
The set of files needed to be secure changed and changed throughout testing and so it ended up as a shell command but an error checked function was provided for the administrator programmer to use instead of appending to the long list in settings.ini section [FILESEC] if you wish or to work with other software.
Those files are:
etc/ftpusers /etc/group /etc/hosts /etc/hosts.allow /etc/hosts.equiv /etc/hosts.lpd /etc/inetd.conf /etc/login.access /etc/login.conf /etc/newsyslog.conf /etc/rc.conf /etc/ssh/sshd_config /etc/sysctl.conf etc/syslog.conf /etc/ttys /etc/crontab /usr/bin/crontab /usr/bin/at /usr/bin/atq /usr/bin/atrm /usr/bin/batch /var/log
The newly applied settings will not take affect until you reset your password.
- Set the correct paths to jailed confs in
harden-ghostbsd.pylines 32-38 and run for each jail. - Copy software to
/rootand have jail start this script at reboot and all settings will be updated upon next reboot. To update all jails simply copysettings.iniwith your own copy script to all appropriate locations for uptake.
crontab -e
@reboot /path/to/harden-ghostbsd.py
- Have all jails pointing to the same rc script via
exec.startand set paths in the script pointing to the same location modified by the script paths. - Add new jail specific entires to
settings.ini [SYSTEM]section for sysctl.conf udpatesecurity.jail.* = 0
- Use mutiple copies of the script and settings.ini for each jail
- Put it in your template
Startup
kern_securelevel_enable = "YES"- Enable access to other than permanently insecure modes
microcode_update_enable = "YES"- Allow CPU microcode/firmware updates
- Disable Sendmail
syslogd_flags="-ss"- Disallow syslogd to bind to a network socket
clear_tmp_enable = "YES"- Clear the /tmp directory on reboot
icmp_drop_redirect="YES"- Disallow redirection of ICMP (ping, echo)
inetd_enable = "NO"- Disallow Network File System to share directories over the network
portmap_enable = "NO"- Disallow portmapping since Network File Systems is disallowed
update_motd = "NO"- Disallow computer system details from being added to /etc/motd on system reboot
System
kern.securelevel = 1(*)- The system immutable and system append-only flags may not be turned off; disks for mounted file systems, /dev/mem and /dev/kmem may not be opened for writing; /dev/io (if your platform has it) may not be opened at all; kernel modules (see kld(4)) may not be loaded or unloaded. The kernel debugger may not be entered using the debug.kdb.enter sysctl. A panic or trap cannot be forced using the debug.kdb.panic, debug.kdb.panic_str and other sysctl's.
security.bsd.see_other_uids = 0- Disallow users from seeing information about processes that are being run by another user (UID)
security.bsd.see_other_gids = 0(*)- Disallow users from seeing information about processes that are being run by another group (GID)
security.bsd.see_jail_proc = 0(Sysctl MIB Entrysysctl -a | grep security.bsd)- Disallow non-root users from seeing processes in jail
security.bsd.unprivileged_read_msgbuf = 0(Sysctl MIB Entrysysctl -a | grep security.bsd)- Disallow non-root users from reading system message buffer
security.bsd.stack_guard_page=1(Java Stack Vulnerability Mitigation (*))kern.randompid = 107(*)- Force kernel to randomize process ID's using above salt value instead of sequential
net.inet.ip.random_id = 1- Randomize IP packet ID
net.inet.ip.redirect = 0- Disallow ICMP host redirects
net.inet.tcp.always_keepalive = 0- Disallow keeping open idle TCP connections
net.inet.tcp.blackhole = 2+(UDP)(*)- Packets that are received on a closed port will not initiate a reply
net.inet.tcp.path_mtu_discovery = 0(*)- Disallows TCP to determine the minimum MTU size on any network that is currently in the path between two hosts
net.inet.icmp.drop_redirect = 1- Pairs with rc.conf startup, as once enabled, it is then set
hw.mds_disable = 3(*)- Enable Microarchitectural Data Sampling Mitigation version
VERW - Change value to
3(AUTO) if using a Hypervisor without MDS Patch
- Enable Microarchitectural Data Sampling Mitigation version
hw.spec_store_bypass_disable = 1(*)- Disallow Speculative Bypass used by Spectre and Meltdown
kern.elf64.allow_wx = 0(*)- Disallow write and execute for shared memory
Kernel
security.bsd.allow_destructive_dtrace = "0"- Disallow DTrace to terminate proccesses
- Test DTrace hardening: Using all 3 commands should result in
Permission deniedorDestructive actions not allowed: dtrace -wn 'tcp:::connect-established { @[args[3]->tcps_raddr] = count(); }'dtrace -wqn tick-1sec'{system("date")}'dtrace -qn tick-1sec'{system("date")}'
hw.ibrs_disable = "3"(*)- Prevent Spectre and Meltdown CPU Vulnerabilities, 3 for AUTO
kern.elf32.aslr.stack = "3"(*)- Address space layout randomization is used to increase the difficulty of performing a buffer overflow attack
- 64bit is enabled by default in 13.2 so you can set this to 0 for 64bit processors or remove
kern.elf32.aslr.pie_enable = "1"- Enable ASLR for Position-Independent Executables (PIE) binaries
Non-Commercial usage, retain and forward author and license data. Modify existing code as needed up to 25% while allowing unlimited new additions. The Software may use or be used by other software.
All Original Digital Artists recieve automatic Copyright.
- Supplemental License here
- Eric Turgeon via the GhostBSD Operating System and the GhostBSD Team meet the terms of Non-Commercial and are thus granted License.
Since this Software uses shell commands it is required to place it in a secure directory with permissions on the parent directory to have no permissions for other /all/world group to write or execute and no network access.
Please follow these guidelines should you find a vulnerability not addressed in the audit.
- Risk - Low
- Impact - Medium
This script has no networking, accesses no sockets, and uses only standard libraries.
Although this script is using subprocess.run(shell=True) the only possibility of shell injection is from the paths customized by the Licensee or unauthorized access to the filesystem the script resides on in order to perform unauthorized modifications to settings.inior the Software which is not a vulnerability of the Software.
Quadhelion Engineering Code Repository
