Guide to the Secure Configuration of Red Hat Enterprise Linux 7
Rules, Groups, and Values defined within the XCCDF Benchmark
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Enable support for BUG()
Disabling this option eliminates support for BUG and WARN, reducing the size of your kernel image and potentially quietly ignoring numerous fatal c...Rule Medium Severity -
Disable compatibility with brk()
Enabling compatiliby with <code>brk()</code> allows legacy binaries to run (i.e. those linked against libc5). But this compatibility comes at the c...Rule Medium Severity -
Disable the 32-bit vDSO
Certain buggy versions of glibc (2.3.3) will crash if they are presented with a 32-bit vDSO that is not mapped at the address indicated in its segm...Rule Low Severity -
Enable checks on credential management
Enable this to turn on some debug checking for credential management. The additional code keeps track of the number of pointers from task_structs t...Rule Low Severity -
Disable kernel debugfs
<code>debugfs</code> is a virtual file system that kernel developers use to put debugging files into. Enable this option to be able to read and wri...Rule Low Severity -
Enable checks on linked list manipulation
Enable this to turn on extended checks in the linked-list walking routines. The configuration that was used to build kernel is available at <code>...Rule Low Severity -
Enable checks on notifier call chains
Enable this to turn on sanity checking for notifier call chains. This is most useful for kernel developers to make sure that modules properly unreg...Rule Low Severity -
Enable checks on scatter-gather (SG) table operations
Scatter-gather tables are mechanism used for high performance I/O on DMA devices. Enable this to turn on checks on scatter-gather tables. The conf...Rule Low Severity -
Configure low address space to protect from user allocation
This is the portion of low virtual memory which should be protected from userspace allocation. This configuration is available from kernel 3.14, bu...Rule Medium Severity -
Disable /dev/kmem virtual device support
Disable support for the /dev/kmem device. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To chec...Rule Low Severity -
Harden memory copies between kernel and userspace
This option checks for obviously wrong memory regions when copying memory to/from the kernel (via copy_to_user() and copy_from_user() functions) by...Rule High Severity -
Disable hibernation
Enable the suspend to disk (STD) functionality, which is usually called "hibernation" in user interfaces. STD checkpoints the system and powers it ...Rule Medium Severity -
Disable IA32 emulation
Disables support for legacy 32-bit programs under a 64-bit kernel. The configuration that was used to build kernel is available at <code>/boot/con...Rule Medium Severity -
Disable the IPv6 protocol
Disable support for IP version 6 (IPv6). The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check...Rule Medium Severity -
Disable kexec system call
<code>kexec</code> is a system call that implements the ability to shutdown your current kernel, and to start another kernel. It is like a reboot b...Rule Low Severity -
Ensure journald is configured to send logs to rsyslog
Data from journald may be stored in volatile memory or persisted locally. Utilities exist to accept remote export of journald logs.Rule Medium Severity -
Disable legacy (BSD) PTY support
Disable the Linux traditional BSD-like terminal names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals, and use only the modern...Rule Medium Severity -
Enable module signature verification
Check modules for valid signatures upon load. Note that this option adds the OpenSSL development packages as a kernel build dependency so that the ...Rule Medium Severity -
Enable automatic signing of all modules
Sign all modules during make modules_install. Without this option, modules must be signed manually, using the scripts/sign-file tool. The configur...Rule Medium Severity -
Require modules to be validly signed
Reject unsigned modules or signed modules with an unknown key. The configuration that was used to build kernel is available at <code>/boot/config-...Rule Medium Severity -
Specify the hash to use when signing modules
This configures the kernel to build and sign modules using <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_kernel_config_module_sig_ha...Rule Medium Severity -
Specify module signing key to use
Setting this option to something other than its default of <code>certs/signing_key.pem</code> will disable the autogeneration of signing keys and a...Rule Medium Severity -
Sign kernel modules with SHA-512
This configures the kernel to build and sign modules using SHA512 as the hash function. The configuration that was used to build kernel is availab...Rule Medium Severity -
Enable poison without sanity check
Skip the sanity checking on alloc, only fill the pages with poison on free. This reduces some of the overhead of the poisoning feature. This config...Rule Medium Severity -
Use zero for poisoning instead of debugging value
Instead of using the existing poison value, fill the pages with zeros. This makes it harder to detect when errors are occurring due to sanitization...Rule Medium Severity -
net.ipv6.conf.default.accept_ra_pinfo
Accept prefix information in router advertisements?Value -
Remove the kernel mapping in user mode
This feature reduces the number of hardware side channels by ensuring that the majority of kernel addresses are not mapped into userspace. This con...Rule High Severity -
Kernel panic oops
Enable the kernel to panic when it oopses. This has the same effect as setting oops=panic on the kernel command line. The configuration that was u...Rule Medium Severity -
Kernel panic timeout
Set the timeout value (in seconds) until a reboot occurs when the kernel panics. A timeout of 0 configures the system to wait forever. With a timeo...Rule Medium Severity -
Disable support for /proc/kkcore
Provides a virtual ELF core file of the live kernel. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. ...Rule Low Severity -
Randomize the address of the kernel image (KASLR)
In support of Kernel Address Space Layout Randomization (KASLR), this randomizes the physical address at which the kernel image is decompressed and...Rule Medium Severity -
Randomize the kernel memory sections
Randomizes the base virtual address of kernel memory sections (physical memory mapping, vmalloc & vmemmap). This configuration is available fro...Rule Medium Severity -
Perform full reference count validation
Enabling this switches the refcounting infrastructure from a fast unchecked atomic_t implementation to a fully state checked implementation, which ...Rule Medium Severity -
Avoid speculative indirect branches in kernel
Compile kernel with the retpoline compiler options to guard against kernel-to-user data leaks by avoiding speculative indirect branches. Requires a...Rule Medium Severity -
Enable seccomp to safely compute untrusted bytecode
This kernel feature is useful for number crunching applications that may need to compute untrusted bytecode during their execution. By using pipes ...Rule Medium Severity -
Ensure journald is configured to write log files to persistent disk
The journald system may store log files in volatile memory or locally on disk. If the logs are only stored in volatile memory they will we lost upo...Rule Medium Severity -
Enable use of Berkeley Packet Filter with seccomp
Enable tasks to build secure computing environments defined in terms of Berkeley Packet Filter programs which implement task-defined system call fi...Rule Medium Severity -
Enable different security models
This allows you to choose different security modules to be configured into your kernel. The configuration that was used to build kernel is availab...Rule Medium Severity -
Enable Yama support
This enables support for LSM module Yama, which extends DAC support with additional system-wide security settings beyond regular Linux discretionar...Rule Medium Severity -
Enable SLUB debugging support
SLUB has extensive debug support features and this allows the allocator validation checking to be enabled. The configuration that was used to buil...Rule Medium Severity -
Enable TCP/IP syncookie support
Normal TCP/IP networking is open to an attack known as SYN flooding. It is denial-of-service attack that prevents legitimate remote users from bein...Rule Medium Severity -
Unmap kernel when running in userspace (aka KAISER)
Speculation attacks against some high-performance processors can be used to bypass MMU permission checks and leak kernel data to userspace. This ca...Rule Medium Severity -
Disable x86 vsyscall emulation
Disabling it is roughly equivalent to booting with vsyscall=none, except that it will also disable the helpful warning if a program tries to use a ...Rule Low Severity -
Kernel GCC plugin configuration
Contains rules that check the configuration of GCC plugins used by the compilerGroup -
Configure Syslog
The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lac...Group -
Ensure rsyslog-gnutls is installed
TLS protocol support for rsyslog is installed. The <code>rsyslog-gnutls</code> package can be installed with the following command: <pre> $ sudo y...Rule Medium Severity -
Ensure rsyslog is Installed
Rsyslog is installed by default. Thersyslogpackage can be installed with the following command:$ sudo yum install rsyslog
Rule Medium Severity -
Enable rsyslog Service
The <code>rsyslog</code> service provides syslog-style logging by default on Red Hat Enterprise Linux 7. The <code>rsyslog</code> service can be e...Rule Medium Severity -
Disable Logwatch on Clients if a Logserver Exists
Does your site have a central logserver which has been configured to report on logs received from all systems? If so: <pre>$ sudo rm /etc/cron.dail...Rule Unknown Severity -
Ensure rsyslog Default File Permissions Configured
rsyslog will create logfiles that do not already exist on the system. This settings controls what permissions will be applied to these newly create...Rule Medium Severity
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