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Patrick Schleizer
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README.md
72
README.md
@ -16,10 +16,10 @@ configuration file.
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Significant hardening is applied by default to a myriad of components within kernel
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space, user space, core dumps, and swap space.
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- Restrict access to kernel addresses through the us of kernel pointers regardless
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- Restrict access to kernel addresses through the use of kernel pointers regardless
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of user privileges.
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- Restrict access to the kernel logs to `CAP_SYSLOG` as the often contain
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- Restrict access to the kernel logs to `CAP_SYSLOG` as they often contain
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sensitive information.
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- Prevent kernel information leaks in the console during boot.
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@ -28,33 +28,33 @@ space, user space, core dumps, and swap space.
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- Restrict loading TTY line disciplines to `CAP_SYS_MODULE`.
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- Restricts the `userfaultfd()` syscall to `CAP_SYS_PTRACE` which reduces the
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- Restrict the `userfaultfd()` syscall to `CAP_SYS_PTRACE`, which reduces the
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likelihood of use-after-free exploits.
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- Disable `kexec` as it can be used to replace the running kernel.
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- Entirely disables the SysRq key so that the Secure Attention Key (SAK)
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can no longer be utilised. See [documentation](https://www.kicksecure.com/wiki/SysRq).
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- Entirely disable the SysRq key so that the Secure Attention Key (SAK)
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can no longer be utilized. See [documentation](https://www.kicksecure.com/wiki/SysRq).
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- Provide the option to disable unprivileged user namespaces as they can lead to
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substantial privilege escalation.
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- Restrict kernel profiling and the performance events system to `CAP_PERFMON`.
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- Randomise the addresses (ASLR) for mmap base, stack, VDSO pages, and heap.
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- Randomize the addresses (ASLR) for mmap base, stack, VDSO pages, and heap.
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- Disable asynchronous I/O (when using Linux kernel version >= 6.6).
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- Restrict usage of `ptrace()` to only processes with `CAP_SYS_PTRACE` as it
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enables programs to inspect and modify other active processes. Provide the
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option to also entirely disable the use of `ptrace()` for all processes.
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option to entirely disable the use of `ptrace()` for all processes.
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- Prevent hardlink and symlink TOCTOU races in world-writable directories.
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- Disallow unintentional writes to files in world-writable directories unless
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they are owned by the directory owner to mitigate some data spoofing attacks.
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- Increase the maximum number of memory map areas a process is able to utilise.
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- Increase the maximum number of memory map areas a process is able to utilize.
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- Disable core dump files and prevent their creation. If core dump files are
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enabled, they will be named based on `core.PID` instead of the default `core`.
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@ -67,17 +67,17 @@ Various networking components of the TCP/IP stack are hardened for IPv4/6.
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- Protect against TCP time-wait assassination hazards.
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- Enables reverse path filtering (source validation) of packets received
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- Enable reverse path filtering (source validation) of packets received
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from all interfaces to prevent IP spoofing.
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- Disable ICMP redirect acceptance and redirect sending messages to
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prevent man-in-the-middle attacks and minimise information disclosure.
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prevent man-in-the-middle attacks and minimize information disclosure.
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- Ignore ICMP echo requests to prevent clock fingerprinting and Smurf attacks.
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- Ignore bogus ICMP error responses.
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- Disable source routing which allows users redirect network traffic that
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- Disable source routing which allows users to redirect network traffic that
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can result in man-in-the-middle attacks.
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- Do not accept IPv6 router advertisements and solicitations.
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@ -85,9 +85,9 @@ Various networking components of the TCP/IP stack are hardened for IPv4/6.
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- Provide the option to disable SACK and DSACK as they have historically been
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a known vector for exploitation.
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- Disable TCP timestamps as it can allow detecting the system time.
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- Disable TCP timestamps as they can allow detecting the system time.
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- Provide the option to log of packets with impossible source or destination
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- Provide the option to log packets with impossible source or destination
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addresses to enable further inspection and analysis.
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- Provide the option to enable IPv6 Privacy Extensions.
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@ -109,19 +109,19 @@ Boot parameters relating to kernel hardening, DMA mitigations, and entropy
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generation are outlined in the `/etc/default/grub.d/40_kernel_hardening.cfg`
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configuration file.
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- Disable merging of slabs with similar size which reduces the risk of
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- Disable merging of slabs with similar size, which reduces the risk of
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triggering heap overflows and limits influencing slab cache layout.
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- Enable memory zeroing at both allocation and free time which mitigate some
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- Enable memory zeroing at both allocation and free time, which mitigates some
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use-after-free vulnerabilities by erasing sensitive information in memory.
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- Enable the kernel page allocator to randomise free lists to limit some data
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exfiltration and ROP attacks especially during the early boot process.
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- Enable the kernel page allocator to randomize free lists to limit some data
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exfiltration and ROP attacks, especially during the early boot process.
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- Enable kernel page table isolation increase KASLR effectiveness and also
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- Enable kernel page table isolation to increase KASLR effectiveness and also
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mitigate the Meltdown CPU vulnerability.
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- Enables randomisation of the kernel stack offset on syscall entries to harden
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- Enable randomization of the kernel stack offset on syscall entries to harden
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against memory corruption attacks.
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- Disable vsyscalls as they are vulnerable to ROP attacks and have now been
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@ -142,10 +142,10 @@ configuration file.
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the busmaster bit on all PCI bridges during the early boot process.
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- Do not credit the CPU or bootloader as entropy sources at boot in order to
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maximise the absolute quantity of entropy in the combined pool.
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maximize the absolute quantity of entropy in the combined pool.
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- Obtain more entropy at boot from RAM as the runtime memory allocator is
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being initialised.
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being initialized.
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- Provide option to disable the entire IPv6 stack to reduce attack surface.
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@ -156,7 +156,7 @@ the `/etc/default/grub.d/41_quiet_boot.cfg` configuration file.
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#### Kernel Module Signature Verification
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Not yet due to issues:
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Not yet implemented due to issues:
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- https://forums.whonix.org/t/enforce-kernel-module-software-signature-verification-module-signing-disallow-kernel-module-loading-by-default/7880/64
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- https://github.com/dell/dkms/issues/359
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@ -167,7 +167,7 @@ See:
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#### Disables the loading of new modules to the kernel after the fact
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Not yet due to issues:
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Not yet implemented due to issues:
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- https://github.com/Kicksecure/security-misc/pull/152
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@ -191,13 +191,13 @@ modules from automatically starting.
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- Framebuffer Drivers: Blacklisted as they are well-known to be buggy, cause
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kernel panics, and are generally only used by legacy devices.
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- Miscellaneous: Blacklist an assortment other modules to prevent them from
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- Miscellaneous: Blacklist an assortment of other modules to prevent them from
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automatically loading.
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Specific kernel modules are entirely disabled to reduce attack surface via
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`/etc/modprobe.d/30_security-misc_disable.conf`. Disabling prohibits kernel
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modules from starting. This approach should not be considered comprehensive,
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rather it is a form of badness enumeration. Any potential candidates for future
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modules from starting. This approach should not be considered comprehensive;
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rather, it is a form of badness enumeration. Any potential candidates for future
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disabling should first be blacklisted for a suitable amount of time.
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- File Systems: Disable uncommon and legacy file systems.
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@ -215,9 +215,9 @@ disabling should first be blacklisted for a suitable amount of time.
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- Network File Systems: Disable uncommon and legacy network file systems.
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- Network Protocols: Wide array of uncommon and legacy network protocols are disabled.
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- Network Protocols: A wide array of uncommon and legacy network protocols are disabled.
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- Miscellaneous: Disable an assortment other modules such as those required
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- Miscellaneous: Disable an assortment of other modules such as those required
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for amateur radio, floppy disks, and vivid.
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- Thunderbolt: Disabled as they are often vulnerable to DMA attacks.
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@ -246,24 +246,24 @@ disabling should first be blacklisted for a suitable amount of time.
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- An initramfs hook sets the sysctl values in `/etc/sysctl.conf` and
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`/etc/sysctl.d` before init is executed so sysctl hardening is enabled as
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early as possible. This is implemented for `initramfs-tools` only because
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this is not needed for `dracut` because `dracut` does that by default, at
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this is not needed for `dracut` as `dracut` does that by default, at
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least on `systemd` enabled systems. Not researched for non-`systemd` systems
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by the author of this part of the readme.
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## Network hardening
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Not yet due to issues:
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Not yet implemented due to issues:
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- https://github.com/Kicksecure/security-misc/pull/145
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- https://github.com/Kicksecure/security-misc/issues/184
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- Unlike version 4, IPv6 addresses can provide information not only about the
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originating network, but also the originating device. We prevent this from
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originating network but also the originating device. We prevent this from
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happening by enabling the respective privacy extensions for IPv6.
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- In addition, we deny the capability to track the originating device in the
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network at all, by using randomized MAC addresses per connection per
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network at all, by using randomized MAC addresses per connection by
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default.
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See:
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@ -320,7 +320,7 @@ A systemd service is triggered on boot to remount all sensitive partitions and
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directories with significantly more secure hardened mount options. Since this
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would require manual tuning for a given specific system, we handle it by
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creating a very solid configuration file for that very system on package
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install.
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installation.
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Not enabled by default yet. In development. Help welcome.
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@ -342,15 +342,15 @@ Not enabled by default yet. In development. Help welcome.
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- Abort login for users with locked passwords -
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`/usr/libexec/security-misc/pam-abort-on-locked-password`.
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- Logging into the root account from a virtual, serial, whatnot console is
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- Logging into the root account from a virtual, serial, or other console is
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prevented by shipping an existing and empty `/etc/securetty` file (deletion
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of `/etc/securetty` has a different effect).
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This package does not yet automatically lock the root account password. It is
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not clear if this would be sane in such a package although, it is recommended to
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not clear if this would be sane in such a package, although it is recommended to
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lock and expire the root account.
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In new Kicksecure builds, root account will be locked by package
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In new Kicksecure builds, the root account will be locked by package
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dist-base-files.
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See:
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