cyberstrikeus CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - 1.7.3
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
The contents of the /etc/issue.net file are displayed to users prior to login for remote connections from configured services.
Unix-based systems have typically displayed information about the OS release and patch level upon logging in to the system. This information can be useful to developers who are developing software for a particular OS platform. If mingetty(8) supports the following options, they display operating system information: \m - machine architecture \r - operating system release \s - operating system name \v - operating system version
Rationale
Warning messages inform users who are attempting to login to the system of their legal status regarding the system and must include the name of the organization that owns the system and any monitoring policies that are in place. Displaying OS and patch level information in login banners also has the side effect of providing detailed system information to attackers attempting to target specific exploits of a system. Authorized users can easily get this information by running the uname -a command once they have logged in.
Audit Procedure
Command Line
Run the following command and verify that the contents match site policy:
cat /etc/issue.net
Run the following command and verify no results are returned:
grep -E -i "(\\v|\\r|\\m|\\s|$(grep '^ID=' /etc/os-release | cut -d= -f2 | sed -e 's/"//g'))" /etc/issue.net
Expected Result
The /etc/issue.net file should contain an appropriate warning banner without OS information references.
Remediation
Command Line
Edit the /etc/issue.net file with the appropriate contents according to your site policy, remove any instances of \m, \r, \s, \v or references to the OS platform:
echo "Authorized uses only. All activity may be monitored and reported." > /etc/issue.net
Default Value
Not applicable.
References
None.
CIS Controls
| Controls Version | Control |
|---|---|
| v7 | 5.1 Establish Secure Configurations |
Assessment Status
Automated