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The Photon operating system must enable hardlink access control protection in the kernel.


Finding ID Version Rule ID IA Controls Severity
V-258903 PHTN-40-000244 SV-258903r933770_rule Medium
By enabling the fs.protected_hardlinks kernel parameter, users can no longer create soft or hard links to files they do not own. Disallowing such hardlinks mitigate vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat().
VMware vSphere 8.0 vCenter Appliance Photon OS 4.0 Security Technical Implementation Guide 2023-10-29


Check Text ( C-62643r933768_chk )
At the command line, run the following command to verify hardlink protection is enabled:

# /sbin/sysctl fs.protected_hardlinks

Example result:

fs.protected_hardlinks = 1

If the "fs.protected_hardlinks" kernel parameter is not set to "1", this is a finding.
Fix Text (F-62552r933769_fix)
Navigate to and open:


Add or update the following line:

fs.protected_hardlinks = 1

At the command line, run the following command to load the new configuration:

# /sbin/sysctl --load /etc/sysctl.d/zz-stig-hardening.conf

Note: If the file zz-stig-hardening.conf does not exist, it must be created.