Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : snapd vulnerabilities (USN-4424-1)

medium Nessus Plugin ID 138552

Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

It was discovered that cloud-init as managed by snapd on Ubuntu Core 16 and Ubuntu Core 18 devices ran on every boot without restrictions.
A physical attacker could exploit this to craft cloud-init user-data/meta-data via external media to perform arbitrary changes on the device to bypass intended security mechanisms such as full disk encryption. This issue did not affect traditional Ubuntu systems.
(CVE-2020-11933) It was discovered that snapctl user-open allowed altering the XDG_DATA_DIRS environment variable when calling the system xdg-open. A malicious snap could exploit this to bypass intended access restrictions to control how the host system xdg-open script opens the URL. This issue did not affect Ubuntu Core systems.
(CVE-2020-11934).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-4424-1

Plugin Details

Severity: Medium

ID: 138552

File Name: ubuntu_USN-4424-1.nasl

Version: 1.6

Type: local

Agent: unix

Published: 7/16/2020

Updated: 10/21/2023

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

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

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 Score Source: CVE-2020-11933

CVSS v3

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.9

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

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

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:snapd, p-cpe:/a:canonical:ubuntu_linux:snapd-xdg-open, p-cpe:/a:canonical:ubuntu_linux:ubuntu-core-launcher, p-cpe:/a:canonical:ubuntu_linux:ubuntu-core-snapd-units, p-cpe:/a:canonical:ubuntu_linux:ubuntu-snappy, p-cpe:/a:canonical:ubuntu_linux:ubuntu-snappy-cli, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:golang-github-snapcore-snapd-dev, p-cpe:/a:canonical:ubuntu_linux:golang-github-ubuntu-core-snappy-dev, p-cpe:/a:canonical:ubuntu_linux:snap-confine

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 7/15/2020

Vulnerability Publication Date: 7/29/2020

Reference Information

CVE: CVE-2020-11933, CVE-2020-11934

USN: 4424-1