Verify that local System.map file (if exists) is readable only by root

Description

Files containing sensitive informations should be protected by restrictive permissions. Most of the time, there is no need that these files need to be read by any non-root user To properly set the permissions of /boot/System.map-*, run the command:

$ sudo chmod 0600 /boot/System.map-*

Rationale

The System.map file contains information about kernel symbols and can give some hints to generate local exploitation.