STIGQter: STIG Summary: Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide Version: 2 Release: 6 Benchmark Date: 01 Jul 2026:

TOSS must enable kernel parameters to enforce discretionary access control on symlinks.

DISA Rule

SV-253136r958702_rule

Vulnerability Number

V-253136

Group Title

SRG-OS-000312-GPOS-00122

Rule Version

TOSS-04-040950

Severity

CAT II

CCI(s)

CCI-002165 - Enforce organization-defined discretionary access control policies over defined subjects and objects.
CCI-002235 - Prevent non-privileged users from executing privileged functions.

Weight

Fix Recommendation

Configure the operating system to enable DAC on symlinks.

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

fs.protected_symlinks = 1

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

$ sudo sysctl --system

Check Contents

Verify the operating system is configured to enable DAC on symlinks with the following commands:

Check the status of the fs.protected_symlinks kernel parameter.

$ sudo sysctl fs.protected_symlinks

fs.protected_symlinks = 1

If "fs.protected_symlinks" is not set to "1" or is missing, this is a finding.

Check that the configuration files are present to enable this kernel parameter.

$ sudo grep -r fs.protected_symlinks /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf

/etc/sysctl.d/99-sysctl.conf:fs.protected_symlinks = 1

If "fs.protected_symlinks" is not set to "1", is missing or commented out, this is a finding.

If conflicting results are returned, this is a finding.

Vulnerability Number

V-253136

Documentable

False

Rule Version

TOSS-04-040950

Severity Override Guidance

Check Content Reference

Target Key

5469