SLEM 5 must implement kptr-restrict to prevent the leaking of internal kernel addresses.

Some adversaries launch attacks with the intent of executing code in nonexecutable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can either be hardware enforced or software enforced, with hardware providing the greater strength of mechanism.

Examples of attacks are buffer overflow attacks.

Verify SLEM 5 prevents leaking of internal kernel addresses with the following command:

     > sudo sysctl kernel.kptr_restrict
     kernel.kptr_restrict = 1

If the kernel parameter "kptr_restrict" is not equal to "1", or nothing is returned, this is a finding.

Configure SLEM 5 to prevent leaking of internal kernel addresses by running the following command:

     > sudo sysctl -w kernel.kptr_restrict=1

If "1" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf":

     > sudo sh -c 'echo "kernel.kptr_restrict=1" >> /etc/sysctl.d/99-stig.conf'

Reload settings from all system configuration files with the following command:

     > sudo sysctl --system