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V-282507

CAT II (Medium)

TOSS 5 must restrict exposed kernel pointer addresses access.

Rule ID

SV-282507r1200501_rule

STIG

Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-001082 CCI-002824

Discussion

Exposing kernel pointers (through procfs or "seq_printf()") exposes kernel writeable structures, which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised. This option disallows any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with "0". Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192, SRG-OS-000433-GPOS-00193

Check Content

Verify the runtime status of the "kernel.kptr_restrict" kernel parameter using the following command:

$ sudo sysctl kernel.kptr_restrict 

kernel.kptr_restrict = 1

If "kernel.kptr_restrict" is not set to "1" or is missing, this is a finding.

Fix Text

Add or edit the following line in a system configuration file in the "/etc/sysctl.d/" directory:

kernel.kptr_restrict = 1

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

$ sudo sysctl --system