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Amazon Linux 2 : setup (ALAS-2019-1158)

medium Nessus Plugin ID 122159

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Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

Setup in Amazon Linux 2 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.
(CVE-2018-1113)

Please note: this update removes the `/sbin/nologin` and `/usr/sbin/nologin` login shells from the `/etc/shells` file due to security reasons. Consequently, when the configuration of the Very Secure File Transfer Protocol Daemon, *vsftpd*, is modified to enable the `chroot_local_user`, FTP logins are impossible.

To work around this problem, add `/sbin/nologin` or `/usr/sbin/nologin`, respectively, to the `/etc/shells` file. As a result, a login shell for users that are allowed to use FTP, but not SSH, is available again. However, note that this workaround exposes
*vsftpd* to the security risk described in this advisory.

Solution

Run 'yum update setup' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2019-1158.html

Plugin Details

Severity: Medium

ID: 122159

File Name: al2_ALAS-2019-1158.nasl

Version: 1.2

Type: local

Agent: unix

Published: 2/14/2019

Updated: 2/12/2020

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.4

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:setup, cpe:/o:amazon:linux:2

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 2/14/2019

Vulnerability Publication Date: 7/3/2018

Reference Information

CVE: CVE-2018-1113

ALAS: 2019-1158