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Amazon Linux 2 : cloud-init (ALAS-2021-1576)

high Nessus Plugin ID 144795

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Synopsis

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

Description

The version of tested product installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2021-1576 advisory.

 - The default cloud-init configuration, in cloud-init 0.6.2 and newer, included ssh_deletekeys: 0, disabling cloud-init's deletion of ssh host keys. In some environments, this could lead to instances created by cloning a golden master or template system, sharing ssh host keys, and being able to impersonate one another or conduct man-in-the-middle attacks. (CVE-2018-10896)

 - cloud-init through 19.4 relies on Mersenne Twister for a random password, which makes it easier for attackers to predict passwords, because rand_str in cloudinit/util.py calls the random.choice function.
 (CVE-2020-8631)

 - In cloud-init through 19.4, rand_user_password in cloudinit/config/cc_set_passwords.py has a small default pwlen value, which makes it easier for attackers to guess passwords. (CVE-2020-8632)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update cloud-init' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2021-1576.html

https://access.redhat.com/security/cve/CVE-2018-10896

https://access.redhat.com/security/cve/CVE-2020-8631

https://access.redhat.com/security/cve/CVE-2020-8632

Plugin Details

Severity: High

ID: 144795

File Name: al2_ALAS-2021-1576.nasl

Version: 1.2

Type: local

Agent: unix

Published: 1/7/2021

Updated: 1/7/2021

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

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Low

Base Score: 3.6

Temporal Score: 2.7

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

CVSS Score Source: CVE-2018-10896

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:cloud-init, 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: 1/5/2021

Vulnerability Publication Date: 8/1/2018

Reference Information

CVE: CVE-2018-10896, CVE-2020-8631, CVE-2020-8632

ALAS: 2021-1576