CVE-2018-1113

Impact:
Low
Public Date:
2018-04-24
CWE:
CWE-285
Bugzilla:
1571094: CVE-2018-1113 setup: nologin listed in /etc/shells violates security expectations
Setup in Fedora and Red Hat Enterprise Linux added /sbin/nologin and /usr/sbin/nologin to /etc/shells. This violates security assumptions made by pam_shells and some daemons which allow access based on a user's shell being listed in /etc/shells. Under some circumstances, users which had their shell changed to /sbin/nologin could still access the system.

Find out more about CVE-2018-1113 from the MITRE CVE dictionary dictionary and NIST NVD.

Statement

Preventing a user from accessing the system without deleting their account is not a simple matter. For utmost security, the account should be deleted. Short of this, we recommend a three-pronged approach:
* change the user's login shell to a harmless command that is not in "/etc/shells" (for example "/bin/false") to prevent commands being run on their behalf
* lock the user's password with "usermod -L" to prevent authentication with pam services
* prevent access to the user's home directory with "chmod 0" or "chown root" and "chmod 700" to prevent authentication with ssh keys etc

CVSS v3 metrics

CVSS3 Base Score 4.8
CVSS3 Base Metrics CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction Required
Scope Unchanged
Confidentiality Low
Integrity Impact Low
Availability Impact Low

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux 7 (setup) RHSA-2018:3249 2018-10-30

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 8 setup Not affected
Red Hat Enterprise Linux 6 setup Affected
Red Hat Enterprise Linux 5 setup Will not fix
Last Modified