Amazon Linux 2023 must enable discretionary access control on hardlinks.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-274169 | AZLX-23-002535 | SV-274169r1120495_rule | CCI-002165 | medium |
| Description | ||||
| 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 mitigates vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat(). Satisfies: SRG-OS-000312-GPOS-00123, SRG-OS-000324-GPOS-00125 | ||||
| STIG | Date | |||
| Amazon Linux 2023 Security Technical Implementation Guide | 2026-02-27 | |||
Details
Check Text (C-274169r1120495_chk)
Verify Amazon Linux 2023 is configured to enable DAC on hardlinks.
Check the status of the fs.protected_hardlinks kernel parameter with the following command:
$ sudo sysctl fs.protected_hardlinks
fs.protected_hardlinks = 1
If "fs.protected_hardlinks" is not set to "1" or is missing, this is a finding.
Fix Text (F-78165r1120494_fix)
Configure Amazon Linux 2023 to enable DAC on hardlinks with the following:
Add or edit the following line in a system configuration file in the "/etc/sysctl.d/" directory:
fs.protected_hardlinks = 1
Load settings from all system configuration files with the following command:
$ sudo sysctl --system