All AIX shells referenced in passwd file must be listed in /etc/shells file, except any shells specified for the purpose of preventing logins.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-215288	SRG-OS-000480-GPOS-00227	AIX7-00-002103	SV-215288r991589_rule	2024-08-16	3

Description
The /etc/shells file lists approved default shells. It helps provide layered defense to the security approach by ensuring users cannot change their default shell to an unauthorized unsecure shell.

ℹ️ Check
Confirm the login shells referenced in the "/etc/passwd" file are listed in the "/etc/security/login.cfg" file's "shells =variable" in the usw stanza by running commands: # more /etc/security/login.cfg \| grep shells \| grep -v '*' shells = /bin/sh,/bin/bsh,/bin/csh,/bin/ksh,/bin/tsh,/bin/ksh93,/usr/bin/sh,/usr/bin/bsh,/usr/bin/csh,/usr/bin/ksh,/usr/bin/tsh # more /etc/shells /bin/csh /bin/ksh /bin/psh /bin/tsh /bin/bsh /usr/bin/csh /usr/bin/ksh /usr/bin/psh /usr/bin/tsh /usr/bin/bsh The "/usr/bin/false", "/bin/false", "/dev/null", "/sbin/nologin" (and equivalents), and "sdshell" will be considered valid shells for use in the "/etc/passwd" file, but will not be listed in the shells stanza. If a shell referenced in "/etc/passwd" is not listed in the shells stanza, excluding the above mentioned shells, this is a finding.

ℹ️ Check

Confirm the login shells referenced in the "/etc/passwd" file are listed in the "/etc/security/login.cfg" file's "shells =variable" in the usw stanza by running commands: # more /etc/security/login.cfg | grep shells | grep -v '*' shells = /bin/sh,/bin/bsh,/bin/csh,/bin/ksh,/bin/tsh,/bin/ksh93,/usr/bin/sh,/usr/bin/bsh,/usr/bin/csh,/usr/bin/ksh,/usr/bin/tsh # more /etc/shells /bin/csh /bin/ksh /bin/psh /bin/tsh /bin/bsh /usr/bin/csh /usr/bin/ksh /usr/bin/psh /usr/bin/tsh /usr/bin/bsh The "/usr/bin/false", "/bin/false", "/dev/null", "/sbin/nologin" (and equivalents), and "sdshell" will be considered valid shells for use in the "/etc/passwd" file, but will not be listed in the shells stanza. If a shell referenced in "/etc/passwd" is not listed in the shells stanza, excluding the above mentioned shells, this is a finding.

✔️ Fix
Use the "chsh" utility or edit the "/etc/passwd" file and correct the error by changing the default shell of the account in error to an acceptable shell name contained in the "/etc/shells file". Alternatively, use the SMIT to change the "/etc/passwd" shell entry.