DRAFT - ANSSI-BP-028 (enhanced)
Rules and Groups employed by this XCCDF Profile
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Configure Kernel Parameter for Accepting Secure Redirects By Default
To set the runtime status of the <code>net.ipv4.conf.default.secure_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0</pre...Rule Medium Severity -
Configure Sending and Accepting Shared Media Redirects by Default
To set the runtime status of the <code>net.ipv4.conf.default.shared_media</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.shared_media=<xccdf-1.2:sub...Rule Medium Severity -
Enable Kernel Parameter to Ignore Bogus ICMP Error Responses on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.icmp_ignore_bogus_error_responses</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_response...Rule Unknown Severity -
Enable Kernel Parameter to Use TCP Syncookies on Network Interfaces
To set the runtime status of the <code>net.ipv4.tcp_syncookies</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.tcp_syncookies=1</pre> To make sure that the settin...Rule Medium Severity -
Network Parameters for Hosts Only
If the system is not going to be used as a router, then setting certain kernel parameters ensure that the host will not perform routing of network traffic.Group -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.conf.all.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.all.send_redirects=0</pre> To make su...Rule Medium Severity -
Disable Kernel Parameter for Sending ICMP Redirects on all IPv4 Interfaces by Default
To set the runtime status of the <code>net.ipv4.conf.default.send_redirects</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.conf.default.send_redirects=0</pre> To...Rule Medium Severity -
Disable Kernel Parameter for IP Forwarding on IPv4 Interfaces
To set the runtime status of the <code>net.ipv4.ip_forward</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.ipv4.ip_forward=0</pre> To make sure that the setting is per...Rule Medium Severity -
nftables
<code>If firewalld or iptables are being used in your environment, please follow the guidance in their respective section and pass-over the guidance in this section.</code><br><br> nftables is a su...Group -
File Permissions and Masks
Traditional Unix security relies heavily on file and directory permissions to prevent unauthorized users from reading or modifying files to which they should not have access. <br> <br> Severa...Group -
Verify Permissions on Important Files and Directories
Permissions for many files on a system must be set restrictively to ensure sensitive information is properly protected. This section discusses important permission restrictions which can be verifie...Group -
Verify that All World-Writable Directories Have Sticky Bits Set
When the so-called 'sticky bit' is set on a directory, only the owner of a given file may remove that file from the directory. Without the sticky bit, any user with write access to a directory may ...Rule Medium Severity -
Verify Permissions on System.map Files
The System.map files are symbol map files generated during the compilation of the Linux kernel. They contain the mapping between kernel symbols and their corresponding memory addresses. In general,...Rule Low 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 -
Enable Kernel Parameter to Enforce DAC on Hardlinks
To set the runtime status of the <code>fs.protected_hardlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protected_hardlinks=1</pre> To make sure that the setting ...Rule Medium Severity -
Enable Kernel Parameter to Enforce DAC on Symlinks
To set the runtime status of the <code>fs.protected_symlinks</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w fs.protected_symlinks=1</pre> To make sure that the setting is...Rule Medium Severity -
Verify Permissions on Files with Local Account Information and Credentials
The default restrictive permissions for files which act as important security databases such as <code>passwd</code>, <code>shadow</code>, <code>group</code>, and <code>gshadow</code> files must be ...Group -
Verify Group Who Owns group File
To properly set the group owner of/etc/group, run the command:$ sudo chgrp root /etc/group
Rule Medium Severity -
Verify Group Who Owns gshadow File
To properly set the group owner of/etc/gshadow, run the command:$ sudo chgrp root /etc/gshadow
Rule Medium Severity -
Verify Group Who Owns passwd File
To properly set the group owner of/etc/passwd, run the command:$ sudo chgrp root /etc/passwd
Rule Medium Severity -
Verify Group Who Owns shadow File
To properly set the group owner of/etc/shadow, run the command:$ sudo chgrp root /etc/shadow
Rule Medium Severity -
Verify User Who Owns group File
To properly set the owner of/etc/group, run the command:$ sudo chown root /etc/group
Rule Medium Severity -
Verify User Who Owns gshadow File
To properly set the owner of/etc/gshadow, run the command:$ sudo chown root /etc/gshadow
Rule Medium Severity -
Verify User Who Owns passwd File
To properly set the owner of/etc/passwd, run the command:$ sudo chown root /etc/passwd
Rule Medium Severity -
Verify User Who Owns shadow File
To properly set the owner of/etc/shadow, run the command:$ sudo chown root /etc/shadow
Rule Medium Severity -
Verify Permissions on group File
To properly set the permissions of/etc/group, run the command:$ sudo chmod 0644 /etc/group
Rule Medium Severity -
Verify Permissions on gshadow File
To properly set the permissions of/etc/gshadow, run the command:$ sudo chmod 0000 /etc/gshadow
Rule Medium Severity -
Verify Permissions on passwd File
To properly set the permissions of/etc/passwd, run the command:$ sudo chmod 0644 /etc/passwd
Rule Medium Severity -
Verify Permissions on shadow File
To properly set the permissions of/etc/shadow, run the command:$ sudo chmod 0000 /etc/shadow
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 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 -
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 nosuid Option to /boot
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/boot</code>. The SUID and SGID permissions should not be required on the boot partition. Add the <...Rule Medium Severity -
Add nosuid Option to /home
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/home</code>. The SUID and SGID permissions should not be required in these user data directories. ...Rule Medium Severity -
Add nodev Option to Non-Root Local Partitions
The <code>nodev</code> mount option prevents files from being interpreted as character or block devices. Legitimate character and block devices should exist only in the <code>/dev</code> directory ...Rule Medium Severity -
Add noexec Option to /tmp
The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/tmp</code>. Add the <code>noexec</code> option to the list of <code>Options</code> in the <cod...Rule Medium Severity -
Add nosuid Option to /tmp
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/tmp</code>. The SUID and SGID permissions should not be required in these world-writable directori...Rule Medium Severity -
Add noexec Option to /var/log
The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/var/log</code>. Add the <code>noexec</code> option to the list of <code>Options</code> in the ...Rule Medium Severity -
Add nosuid Option to /var/log
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/var/log</code>. The SUID and SGID permissions should not be required in directories containing log...Rule Medium Severity -
Add nosuid Option to /var
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/var</code>. The SUID and SGID permissions should not be required for this directory. Add the <code...Rule Medium Severity -
Add noexec Option to /var/tmp
The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/var/tmp</code>. Add the <code>noexec</code> option to the list of <code>Options</code> in the ...Rule Medium Severity -
Add nosuid Option to /var/tmp
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/var/tmp</code>. The SUID and SGID permissions should not be required in these world-writable direc...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 -
Kernel panic on oops
To set the runtime status of the <code>kernel.panic_on_oops</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.panic_on_oops=1</pre> To make sure that the setting is p...Rule Medium Severity -
Disallow kernel profiling by unprivileged users
To set the runtime status of the <code>kernel.perf_event_paranoid</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.perf_event_paranoid=2</pre> To make sure that the ...Rule Low 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
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