Use of insufficiently random values in cloud-init (Ubuntu package) - CVE-2020-8631

Vulnerability identifier: #VU51627

CSH Severity: Low

CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2020-8631

CWE-ID: CWE-330

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to predict passwords.

The vulnerability exists due to cloud-init relies on Mersenne Twister for a random password, which uses the random.choice() function in rand_str() in cloudinit/util.py. A local user can guess randomly generated passwords and gain unauthorized access.

cloud-init (Ubuntu package)
cloud-init
cloud-init-help
cloud-init (Red Hat package)
Amazon Linux AMI
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
openEuler

Install updates from vendor's website.

cloud-init (Ubuntu package) - update to 20.1
cloud-init - update to 19.4-2
cloud-init-help - update to 19.4-2
cloud-init (Red Hat package) - update to 19.4-11.el8

• http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00042.html
• https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1860795
• https://github.com/canonical/cloud-init/pull/204
• https://lists.debian.org/debian-lts-announce/2020/02/msg00021.html

• Multiple vulnerabilities in Canonical cloud-init
• Amazon Linux AMI update for cloud-init
• Red Hat Enterprise Linux 8 update for cloud-init
• openEuler 20.03 LTS update for cloud-init