Amazon Linux AMI : ruby22 / ruby23 (ALAS-2017-906)

critical Nessus Plugin ID 103603


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


SMTP command injection via CRLF sequences in RCPT TO or MAIL FROM commands in Net::SMTP

A SMTP command injection flaw was found in the way Ruby's Net::SMTP module handled CRLF sequences in certain SMTP commands. An attacker could potentially use this flaw to inject SMTP commands in a SMTP session in order to facilitate phishing attacks or spam campaigns.

Escape sequence injection vulnerability in the Basic authentication of WEBrick

The Basic authentication code in WEBrick library in Ruby allows remote attackers to inject terminal emulator escape sequences into its log and possibly execute arbitrary commands via a crafted user name.

Buffer underrun in OpenSSL ASN1 decode

The decode method in the OpenSSL::ASN1 module in Ruby allows attackers to cause a denial of service (interpreter crash) via a crafted string.

No size limit in summary length of gem spec

RubyGems is vulnerable to maliciously crafted gem specifications to cause a denial of service attack against RubyGems clients who have issued a `query` command. (CVE-2017-0900)

Arbitrary file overwrite due to incorrect validation of specification name

RubyGems fails to validate specification names, allowing a maliciously crafted gem to potentially overwrite any file on the filesystem.

DNS hijacking vulnerability

RubyGems is vulnerable to a DNS hijacking vulnerability that allows a MITM attacker to force the RubyGems client to download and install gems from a server that the attacker controls. (CVE-2017-0902)

Buffer underrun vulnerability in Kernel.sprintf

Ruby is vulnerable to a malicious format string which contains a precious specifier (*) with a huge minus value. Such situation can lead to a buffer overrun, resulting in a heap memory corruption or an information disclosure from the heap. (CVE-2017-0898)

Escape sequence in the 'summary' field of gemspec

RubyGems is vulnerable to maliciously crafted gem specifications that include terminal escape characters. Printing the gem specification would execute terminal escape sequences. (CVE-2017-0899)

Arbitrary heap exposure during a JSON.generate call

Ruby can expose arbitrary memory during a JSON.generate call. The issues lies in using strdup in ext/json/ext/generator/generator.c, which will stop after encountering a '\\0' byte, returning a pointer to a string of length zero, which is not the length stored in space_len. (CVE-2017-14064)

A vulnerability was found where the rubygems module was vulnerable to an unsafe YAML deserialization when inspecting a gem. Applications inspecting gem files without installing them can be tricked to execute arbitrary code in the context of the ruby interpreter. (CVE-2017-0903)


Run 'yum update ruby22' to update your system.

Run 'yum update ruby23' to update your system.

See Also

Plugin Details

Severity: Critical

ID: 103603

File Name: ala_ALAS-2017-906.nasl

Version: 3.7

Type: local

Agent: unix

Published: 10/3/2017

Updated: 7/10/2019

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

Risk Information


Risk Factor: Medium

Score: 6.7


Risk Factor: High

Base Score: 9.3

Temporal Score: 7.3

Vector: AV:N/AC:M/Au:N/C:C/I:C/A:C

Temporal Vector: E:POC/RL:OF/RC:C


Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:ruby22, p-cpe:/a:amazon:linux:ruby22-debuginfo, p-cpe:/a:amazon:linux:ruby22-devel, p-cpe:/a:amazon:linux:ruby22-doc, p-cpe:/a:amazon:linux:ruby22-irb, p-cpe:/a:amazon:linux:ruby22-libs, p-cpe:/a:amazon:linux:ruby23, p-cpe:/a:amazon:linux:ruby23-debuginfo, p-cpe:/a:amazon:linux:ruby23-devel, p-cpe:/a:amazon:linux:ruby23-doc, p-cpe:/a:amazon:linux:ruby23-irb, p-cpe:/a:amazon:linux:ruby23-libs, p-cpe:/a:amazon:linux:rubygem22-bigdecimal, p-cpe:/a:amazon:linux:rubygem22-io-console, p-cpe:/a:amazon:linux:rubygem22-psych, p-cpe:/a:amazon:linux:rubygem23-bigdecimal, p-cpe:/a:amazon:linux:rubygem23-did_you_mean, p-cpe:/a:amazon:linux:rubygem23-io-console, p-cpe:/a:amazon:linux:rubygem23-json, p-cpe:/a:amazon:linux:rubygem23-psych, p-cpe:/a:amazon:linux:rubygems22, p-cpe:/a:amazon:linux:rubygems22-devel, p-cpe:/a:amazon:linux:rubygems23, p-cpe:/a:amazon:linux:rubygems23-devel, cpe:/o:amazon:linux

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: 1/18/2018

Vulnerability Publication Date: 6/12/2017

Reference Information

CVE: CVE-2015-9096, CVE-2017-0898, CVE-2017-0899, CVE-2017-0900, CVE-2017-0901, CVE-2017-0902, CVE-2017-0903, CVE-2017-10784, CVE-2017-14033, CVE-2017-14064

ALAS: 2017-906