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AlmaLinux OS 9 must enable kernel parameters to enforce discretionary access control (DAC) on symlinks.

An XCCDF Rule

Description

By enabling the fs.protected_symlinks kernel parameter, symbolic links are permitted to be followed only when outside a sticky world-writable directory, or when the user identifier (UID) of the link and follower match, or when the directory owner matches the symlink's owner. Disallowing such symlinks helps mitigate vulnerabilities based on unsecure file systems accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat().

ID
SV-269145r1050027_rule
Version
ALMA-09-007170
Severity
Medium
References
Updated

Remediation Templates

A Manual Procedure

Configure AlmaLinux OS 9 to enable DAC on symlinks with the following command:

$ echo "fs.protected_symlinks = 1" > /etc/sysctl.d/60-symlinks.conf

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

$ sysctl --system