Australian Cyber Security Centre (ACSC) Essential Eight
Rules and Groups employed by this XCCDF Profile
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Ensure All SUID Executables Are Authorized
The SUID (set user id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SUID files is determine if any were not installe...Rule Medium Severity -
Ensure No World-Writable Files Exist
It is generally a good idea to remove global (other) write access to a file when it is discovered. However, check with documentation for specific applications before making changes. Also, monitor f...Rule Medium Severity -
Verify File Permissions Within Some Important Directories
Some directories contain files whose confidentiality or integrity is notably important and may also be susceptible to misconfiguration over time, particularly if unpackaged software is installed. A...Group -
Verify that System Executables Have Root Ownership
System executables are stored in the following directories by default: <pre>/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sbin</pre> All files in these directories should be ...Rule Medium Severity -
Verify that Shared Library Files Have Root Ownership
System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by default: <pre>/lib /lib64 /usr/lib /usr/lib64 </pr...Rule Medium Severity -
Verify that System Executables Have Restrictive Permissions
System executables are stored in the following directories by default: <pre>/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sbin</pre> All files in these directories should not...Rule Medium Severity -
Verify that Shared Library Files Have Restrictive Permissions
System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by default: <pre>/lib /lib64 /usr/lib /usr/lib64 </pr...Rule Medium Severity -
Restrict Partition Mount Options
System partitions can be mounted with certain options that limit what files on those partitions can do. These options are set in the <code>/etc/fstab</code> configuration file, and can be used to m...Group -
Add nodev Option to /dev/shm
The <code>nodev</code> mount option can be used to prevent creation of device files in <code>/dev/shm</code>. Legitimate character and block devices should not exist within temporary directories li...Rule Medium Severity -
Add noexec Option to /dev/shm
The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/dev/shm</code>. It can be dangerous to allow the execution of binaries from world-writable tem...Rule Medium Severity -
Add nosuid Option to /dev/shm
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/dev/shm</code>. The SUID and SGID permissions should not be required in these world-writable dire...Rule Medium Severity -
Restrict Programs from Dangerous Execution Patterns
The recommendations in this section are designed to ensure that the system's features to protect against potentially dangerous program execution are activated. These protections are applied at the ...Group -
Restrict Access to Kernel Message Buffer
To set the runtime status of the <code>kernel.dmesg_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.dmesg_restrict=1</pre> To make sure that the setting is...Rule Low Severity -
Disable Kernel Image Loading
To set the runtime status of the <code>kernel.kexec_load_disabled</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.kexec_load_disabled=1</pre> To make sure that the ...Rule Medium Severity -
Disable Access to Network bpf() Syscall From Unprivileged Processes
To set the runtime status of the <code>kernel.unprivileged_bpf_disabled</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.unprivileged_bpf_disabled=1</pre> To make su...Rule Medium Severity -
Restrict usage of ptrace to descendant processes
To set the runtime status of the <code>kernel.yama.ptrace_scope</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.yama.ptrace_scope=1</pre> To make sure that the sett...Rule Medium Severity -
Harden the operation of the BPF just-in-time compiler
To set the runtime status of the <code>net.core.bpf_jit_harden</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.core.bpf_jit_harden=2</pre> To make sure that the settin...Rule Medium Severity -
Enable ExecShield
ExecShield describes kernel features that provide protection against exploitation of memory corruption errors such as buffer overflows. These features include random placement of the stack and othe...Group -
Restrict Exposed Kernel Pointer Addresses Access
To set the runtime status of the <code>kernel.kptr_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.kptr_restrict=<xccdf-1.2:sub idref="xccdf_org.ssgproject...Rule Medium Severity -
Enable Randomized Layout of Virtual Address Space
To set the runtime status of the <code>kernel.randomize_va_space</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.randomize_va_space=2</pre> To make sure that the se...Rule Medium Severity
Node 2
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