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6.1.1 Audit system file permissions

Warning! Audit Deprecated

This audit has been deprecated and will be removed in a future update.

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Information

The RPM package manager has a number of useful options. One of these, the -V option, can be used to verify that system packages are correctly installed. The V option can be used to verify a particular package or to verify all system packages. If no output is returned, the package is installed correctly. The following table describes the meaning of output from the verify option:

Code Meaning

S File size differs.

M File mode differs (includes permissions and file type).

5 The MD5 checksum differs.

D The major and minor version numbers differ on a device file.

L A mismatch occurs in a link.

U The file ownership differs.

G The file group owner differs.

T The file time (mtime) differs.

The rpm -qf command can be used to determine which package a particular file belongs to. For example the following commands determines which package the /etc/ssh/sshd_config file belongs to:

# rpm -qf /etc/ssh/sshd_config

openssh-server-7.4p1-21.el7.x86_64

To verify the settings for the package that controls the /bin/bash file, run the following:

# rpm -V openssh-server-7.4p1-21.el7.x86_64

S.5....T. c /etc/ssh/sshd_config

Note: You can feed the output of the rpm -qf command to the rpm -V command:

# rpm -V $(rpm -qf /etc/ssh/sshd_config)

S.5....T. c /etc/ssh/sshd_config




Notes:

Since packages and important files may change with new updates and releases, it is recommended to verify everything, not just a finite list of files. This can be a time consuming task and results may depend on site policy therefore it is not a scorable benchmark item, but is provided for those interested in additional security measures.

Some of the recommendations of this benchmark alter the state of files audited by this recommendation. The audit command will alert for all changes to a file permissions even if the new state is more secure than the default.

Rationale:

It is important to confirm that packaged system files and directories are maintained with the permissions they were intended to have from the OS distributor or in accordance with local site policy.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

Investigate the results to ensure any discrepancies found are understood and support proper secure operation of the system.

References:

https://docs.fedoraproject.org/en-US/fedora/rawhide/system-administrators-guide/RPM/#s2-rpm-verifying

See Also

https://workbench.cisecurity.org/files/2948

Item Details

Category: SYSTEM AND INFORMATION INTEGRITY

References: 800-53|SI-7(1), CSCv7|14.6

Plugin: Unix

Control ID: d868856b8a218f3da5f72895059f72b1b9a262813c23c52d8d556206533159c1