Title

Amazon Linux 2023 must disable access to network bpf system call from nonprivileged processes. (Cat II impact)

Discussion

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.

Check Content

Verify Amazon Linux 2023 prevents privilege escalation through the kernel by disabling access to the bpf system call with the following commands: $ sudo 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.

Fix Text

Configure Amazon Linux 2023 to prevent privilege escalation through the kernel by disabling access to the bpf syscall by adding the following line to a file, in the "/etc/sysctl.d" directory: kernel.unprivileged_bpf_disabled = 1 The system configuration files must be reloaded for the changes to take effect. To reload the contents of the files, run the following command: $ sudo sysctl --system

Additional Identifiers

Rule ID: SV-274004r1120000_rule

Vulnerability ID: V-274004

Group Title: SRG-OS-000132-GPOS-00067

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.