Debian DLA-2016-1 : ssvnc security update

critical Nessus Plugin ID 131434

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Synopsis

The remote Debian host is missing a security update.

Description

Several vulnerabilities have been identified in the VNC code of ssvnc, an encryption-capable VNC client..

The vulnerabilities referenced below are issues that have originally been reported against Debian source package libvncserver (which also ships the libvncclient shared library). The ssvnc source package in Debian ships a custom-patched, stripped down and outdated variant of libvncclient, thus some of libvncclient's security fixes required porting over.

CVE-2018-20020

LibVNC contained heap out-of-bound write vulnerability inside structure in VNC client code that can result remote code execution

CVE-2018-20021

LibVNC contained a CWE-835: Infinite loop vulnerability in VNC client code. Vulnerability allows attacker to consume excessive amount of resources like CPU and RAM

CVE-2018-20022

LibVNC contained multiple weaknesses CWE-665: Improper Initialization vulnerability in VNC client code that allowed attackers to read stack memory and could be abused for information disclosure. Combined with another vulnerability, it could be used to leak stack memory layout and in bypassing ASLR.

CVE-2018-20024

LibVNC contained NULL pointer dereference in VNC client code that could result DoS.

For Debian 8 'Jessie', these problems have been fixed in version 1.0.29-2+deb8u1.

We recommend that you upgrade your ssvnc packages.

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

Solution

Upgrade the affected ssvnc package.

Plugin Details

Severity: Critical

ID: 131434

File Name: debian_DLA-2016.nasl

Version: 1.4

Type: local

Agent: unix

Family: Debian Local Security Checks

Published: 12/3/2019

Updated: 1/11/2021

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

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

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

CVSS Score Source: CVE-2018-20020

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/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: cpe:/o:debian:debian_linux:8.0, p-cpe:/a:debian:debian_linux:ssvnc

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

Exploit Ease: No known exploits are available

Patch Publication Date: 11/29/2019

Vulnerability Publication Date: 12/19/2018

Reference Information

CVE: CVE-2018-20020, CVE-2018-20021, CVE-2018-20022, CVE-2018-20024

Detections

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