RHEL 9 must enable hardening for the Berkeley Packet Filter just-in-time compiler.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-257942	SRG-OS-000480-GPOS-00227	RHEL-09-251045	SV-257942r1155718_rule	2025-11-24	2

Description
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Enabling hardening for the Berkeley Packet Filter (BPF) Just-in-time (JIT) compiler aids in mitigating JIT spraying attacks. Setting the value to "2" enables JIT hardening for all users. The sysctl --system command will load settings from all system configuration files. All configuration files are sorted by their filename in lexicographical order, regardless of the directories in which they reside. If multiple files specify the same option, the entry in the file with the lexicographically latest name will take precedence. Files are read from directories in the following list from top to bottom. Once a file of a given filename is loaded, any file of the same name in subsequent directories is ignored. /etc/sysctl.d/.conf /run/sysctl.d/.conf /usr/local/lib/sysctl.d/.conf /usr/lib/sysctl.d/.conf /lib/sysctl.d/*.conf /etc/sysctl.conf

Description

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Enabling hardening for the Berkeley Packet Filter (BPF) Just-in-time (JIT) compiler aids in mitigating JIT spraying attacks. Setting the value to "2" enables JIT hardening for all users. The sysctl --system command will load settings from all system configuration files. All configuration files are sorted by their filename in lexicographical order, regardless of the directories in which they reside. If multiple files specify the same option, the entry in the file with the lexicographically latest name will take precedence. Files are read from directories in the following list from top to bottom. Once a file of a given filename is loaded, any file of the same name in subsequent directories is ignored. /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf

ℹ️ Check
Verify RHEL 9 enables hardening for the BPF JIT compiler. Check the status of the "net.core.bpf_jit_harden" parameter with the following command: $ sudo sysctl net.core.bpf_jit_harden net.core.bpf_jit_harden = 2 If "net.core.bpf_jit_harden" is not equal to "2" or is missing, this is a finding.

✔️ Fix
Configure RHEL 9 to enable hardening for the BPF JIT compiler. Create the drop-in file if it does not already exist: $ sudo vi /etc/sysctl.d/99-net_core-bpf_jit_harden.conf Add the following line to the file: net.core.bpf_jit_harden = 2 Reload settings from all system configuration files with the following command: $ sudo sysctl --system