STIG ID: ALMA-09-040720 | SRG: SRG-OS-000132-GPOS-00067 | Severity: medium | CCI: | Vulnerability Id: V-269422
Loading and accessing the packet filters programs and maps using the bpf() system call has the potential of revealing sensitive information about the kernel state.
Configure AlmaLinux OS 9 to prevent privilege escalation through the kernel by disabling access to the bpf syscall with the following command:
$ echo "kernel.unprivileged_bpf_disabled = 1" > /etc/sysctl.d/60-bpf.conf
Load settings from all system configuration files with the following command:
$ sysctl --system
Verify AlmaLinux OS 9 prevents privilege escalation thru the kernel by disabling access to the bpf system call with the following commands:
$ sysctl kernel.unprivileged_bpf_disabled
kernel.unprivileged_bpf_disabled = 1
If the returned line does not have a value of "1", or a line is not returned, this is a finding.
Check that the configuration files are present to enable this kernel parameter.
$ /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F kernel.unprivileged_bpf_disabled | tail -1
kernel.unprivileged_bpf_disabled = 1
If "kernel.unprivileged_bpf_disabled" is not set to "1", or nothing is returned, this is a finding.