Title

The SSH client must not send environment variables to the server or must only send those pertaining to locale. (Cat III impact)

Discussion

Environment variables can be used to change the behavior of remote sessions and should be limited. Locale environment variables specify the language, character set, and other features modifying the operation of software to match the user's preferences.

Check Content

Check the SSH client configuration for the SendEnv setting. # grep -i SendEnv /etc/ssh/ssh_config | grep -v '^#' If any line is returned other than those permitting LOCALE or LC_* environment variables, this is a finding.

Fix Text

Edit the SSH client configuration and remove (or edit) the SendEnv setting(s) to only accept LOCALE or LC_* environment variables.

Additional Identifiers

Rule ID: SV-26772r1_rule

Vulnerability ID: V-22478

Group Title: GEN005529

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.