4.9.1 Ensure root access is controlled

Information

Restricts access to root via su to members of a specific group. Direct login via console and/or remote login via telnet is blocked.

-

For accountability, no direct access to root is allowed.

-

The attributes here control access to root for programs other than OpenSSH.

-

Setting the sugroups attribute to SUADMIN ensures that only members of the this group are able to su root. This makes it more difficult for an attacker to use a stolen root password as the attacker first has to get access to a system user ID.

-

Access via a

console

(e.g., /dev/vty0 or /dev/tty0) is only permitted when there are external controls managing accountability of access to the console. For example, HMC access must not be via the account hscroot ; a physical console is accessible only after a hard-copy log has been entered and verified before physical access is granted to the (data center) console terminal.

-

The group system is not recommended as it is not uncommon for other accounts to be included in this OS-provided group (gid==0).

Solution

In /etc/security/user set the root stanza sugroups attribute to SUADMIN and ensure the login and rlogin attributes are set to

false

:

lsgroup SUADMIN >/dev/null || mkgroup -a SUADMIN
chuser login=false rlogin=false sugroups=SUADMIN root
- NOTE: For the remediation the setting of su is irrelevant.

Impact:

- When scoring - the attribute login may be true as long as access to the HMC is not via the account name hscroot
- In any case, sugroups should not equal ALL

See Also

https://workbench.cisecurity.org/benchmarks/10385

Item Details

Category: ACCESS CONTROL, CONFIGURATION MANAGEMENT, IDENTIFICATION AND AUTHENTICATION, SYSTEM AND SERVICES ACQUISITION

References: 800-53|AC-6(2), 800-53|AC-6(5), 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|IA-5, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv7|4.1, CSCv7|5.1

Plugin: Unix

Control ID: bd3d611b10d6af497566f1b1c0371ba7c3911b680cde62fc3ef5d18c75ceff8e