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Amazon Linux AMI : openssh (ALAS-2019-1313)

medium Nessus Plugin ID 130403

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Synopsis

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

Description

An issue was discovered in OpenSSH 7.9. Due to missing character encoding in the progress display, a malicious server (or Man-in-The-Middle attacker) can employ crafted object names to manipulate the client output, e.g., by using ANSI control codes to hide additional files being transferred. This affects refresh_progress_meter() in progressmeter.c. (CVE-2019-6109)

An issue was discovered in OpenSSH 7.9. Due to the scp implementation being derived from 1983 rcp, the server chooses which files/directories are sent to the client. However, the scp client only performs cursory validation of the object name returned (only directory traversal attacks are prevented). A malicious scp server (or Man-in-The-Middle attacker) can overwrite arbitrary files in the scp client target directory. If recursive operation (-r) is performed, the server can manipulate subdirectories as well (for example, to overwrite the .ssh/authorized_keys file). (CVE-2019-6111)

In OpenSSH 7.9, scp.c in the scp client allows remote SSH servers to bypass intended access restrictions via the filename of . or an empty filename. The impact is modifying the permissions of the target directory on the client side. (CVE-2018-20685)

Solution

Run 'yum update openssh' to update your system.

See Also

https://alas.aws.amazon.com/ALAS-2019-1313.html

Plugin Details

Severity: Medium

ID: 130403

File Name: ala_ALAS-2019-1313.nasl

Version: 1.4

Type: local

Agent: unix

Published: 10/31/2019

Updated: 4/16/2024

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.1

CVSS v2

Risk Factor: Medium

Base Score: 5.8

Temporal Score: 4.5

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

CVSS Score Source: CVE-2019-6111

CVSS v3

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 6.1

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

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

CVSS Score Source: CVE-2019-6109

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:openssh-clients, p-cpe:/a:amazon:linux:openssh-cavs, p-cpe:/a:amazon:linux:openssh-keycat, p-cpe:/a:amazon:linux:pam_ssh_agent_auth, p-cpe:/a:amazon:linux:openssh-server, p-cpe:/a:amazon:linux:openssh-ldap, cpe:/o:amazon:linux, p-cpe:/a:amazon:linux:openssh, p-cpe:/a:amazon:linux:openssh-debuginfo

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 10/28/2019

Vulnerability Publication Date: 1/10/2019

Reference Information

CVE: CVE-2018-20685, CVE-2019-6109, CVE-2019-6111

ALAS: 2019-1313