TMA-COS-5.1.18
Ensure SSH warning banner is configured
LowLevel 2Automatedcos
Description
The Banner parameter specifies a file whose contents must be sent to the remote user before authentication is permitted. By default, no banner is displayed. Banners are used to warn connecting users of the particular site's policy regarding connection. Presenting a warning message prior to the normal user login may assist the prosecution of trespassers on the computer system.
How it is checked
Audit method: Shell command
shell
alt0() { command -v grep >/dev/null 2>&1 || { echo "step1: grep not installed"; return 1; }; command -v sshd >/dev/null 2>&1 || { echo "step1: sshd not installed"; return 1; }; o=$(bash -c 'sshd -T | grep banner' 2>&1); printf '%s\n' "$o" | tr -s ' \t' ' ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'Banner /etc/issue.net' || { echo step1: missing 'Banner /etc/issue.net'; return 1; }; }; if alt0; then echo compliant; fi- Expected output
compliant
How it is fixed
Fix method: Guidance or infrastructure patch
Edit the /etc/ssh/sshd_config file to set the parameter as follows: Banner /etc/issue.net
Properties
- Operating systems
- Any
- Tags
- container-optimized-oscosssh
- Reference
- CIS Google Container-Optimized OS Benchmark v1.2.0 - 5.1.18 Ensure SSH warning banner is configured
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
shell
tmaegis scan --target cos --level 2