cis-ubuntu2004-v300-1-6-4

DevOps & Security

Ensure access to /etc/motd is configured

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1.6.4 Ensure access to /etc/motd is configured (Automated)

Profile

Level 1 - Server
Level 1 - Workstation

Description

The contents of the /etc/motd file are displayed to users after login and function as a message of the day for authenticated users.

Rationale

IF - the /etc/motd file does not have the correct access configured, it could be modified by unauthorized users with incorrect or misleading information.

Audit Procedure

Command Line

Run the following command and verify that if /etc/motd exists, Access is 644 or more restrictive, Uid and Gid are both 0/root:

# [ -e /etc/motd ] && stat -Lc 'Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/motd

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
  -- OR --
Nothing is returned

Expected Result

Either Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) or nothing returned (file does not exist).

Remediation

Command Line

Run the following commands to set mode, owner, and group on /etc/motd:

# chown root:root $(readlink -e /etc/motd)
# chmod u-x,go-wx $(readlink -e /etc/motd)

OR -

Run the following command to remove the /etc/motd file:

# rm /etc/motd

References

NIST SP 800-53 Rev. 5: AC-3, MP-2

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	3.3 Configure Data Access Control Lists	*	*	*
v7	14.6 Protect Information through Access Control Lists	*	*	*

MITRE ATT&CK Mappings: T1222, T1222.002 | TA0005 | M1022