Title

The /etc/shells (or equivalent) file must exist. (Cat II impact)

Discussion

The shells file (or equivalent) lists approved default shells. It helps provide layered defense to the security approach by ensuring users cannot change their default shell to an unauthorized shell that may not be secure.

Check Content

Verify /etc/shells exists. # ls -l /etc/shells If the file does not exist, this is a finding.

Fix Text

Create a /etc/shells file containing a list of valid system shells. The list below contains the default shells from the shells(4) man page. Procedure (the command is 24 lines long): cat >/etc/shells <<EOF /bin/bash /bin/csh /bin/jsh /bin/ksh /bin/pfcsh /bin/pfksh /bin/pfsh /bin/sh /bin/tcsh /bin/zsh /sbin/jsh /sbin/sh /usr/bin/bash /usr/bin/csh /usr/bin/jsh /usr/bin/ksh /usr/bin/pfcsh /usr/bin/pfksh /usr/bin/pfsh /usr/bin/sh /usr/bin/tcsh /usr/bin/zsh EOF

Additional Identifiers

Rule ID: SV-226566r603265_rule

Vulnerability ID: V-226566

Group Title: SRG-OS-000480

Expert Comments

CCIs tied to check.

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