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Ubuntu 16.04 ESM / 18.04 ESM / 20.04 ESM : Fail2ban vulnerability (USN-5232-1)

high Nessus Plugin ID 183171

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Synopsis

The remote Ubuntu host is missing a security update.

Description

The remote Ubuntu 16.04 ESM / 18.04 ESM / 20.04 ESM host has a package installed that is affected by a vulnerability as referenced in the USN-5232-1 advisory.

 - fail2ban is a daemon to ban hosts that cause multiple authentication errors. In versions 0.9.7 and prior, 0.10.0 through 0.10.6, and 0.11.0 through 0.11.2, there is a vulnerability that leads to possible remote code execution in the mailing action mail-whois. Command `mail` from mailutils package used in mail actions like `mail-whois` can execute command if unescaped sequences (`\n~`) are available in foreign input (for instance in whois output). To exploit the vulnerability, an attacker would need to insert malicious characters into the response sent by the whois server, either via a MITM attack or by taking over a whois server. The issue is patched in versions 0.10.7 and 0.11.3. As a workaround, one may avoid the usage of action `mail-whois` or patch the vulnerability manually. (CVE-2021-32749)

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

Solution

Update the affected fail2ban package.

See Also

https://ubuntu.com/security/notices/USN-5232-1

Plugin Details

Severity: High

ID: 183171

File Name: ubuntu_USN-5232-1.nasl

Version: 1.0

Type: local

Agent: unix

Published: 10/16/2023

Updated: 10/16/2023

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.3

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

CVSS Score Source: CVE-2021-32749

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.3

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:esm, cpe:/o:canonical:ubuntu_linux:18.04:-:esm, cpe:/o:canonical:ubuntu_linux:20.04:-:esm, p-cpe:/a:canonical:ubuntu_linux:fail2ban

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/12/2022

Vulnerability Publication Date: 7/16/2021

Reference Information

CVE: CVE-2021-32749

USN: 5232-1