Amazon Linux AMI update for ruby23

Published: 2018-12-07

Risk	Low
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2018-16396 CVE-2018-16395
CWE-ID	CWE-20
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Amazon Linux AMI Operating systems & Components / Operating system
Vendor	Amazon Web Services

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Security restrictions bypass

EUVDB-ID: #VU15725

Risk: Low

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-16396

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass security restrictions on the target system.

The weakness exists due to the tainted flags are not propagated with the B, b, H, and h directives. A remote attacker can supply inputs by Array#pack and/or String#unpack with these directives and checks the reliability with tainted flags and cause the check to be wrong to bypass security restrictions and conduct further attacks.

Mitigation

Update the affected packages.

i686:
    ruby23-devel-2.3.8-1.20.amzn1.i686
    ruby23-libs-2.3.8-1.20.amzn1.i686
    rubygem23-io-console-0.4.5-1.20.amzn1.i686
    ruby23-2.3.8-1.20.amzn1.i686
    rubygem23-json-1.8.3.1-1.20.amzn1.i686
    rubygem23-psych-2.1.0.1-1.20.amzn1.i686
    rubygem23-bigdecimal-1.2.8-1.20.amzn1.i686
    ruby23-debuginfo-2.3.8-1.20.amzn1.i686

noarch:
    ruby23-doc-2.3.8-1.20.amzn1.noarch
    rubygem23-did_you_mean-1.0.0-1.20.amzn1.noarch
    rubygems23-2.5.2.3-1.20.amzn1.noarch
    ruby23-irb-2.3.8-1.20.amzn1.noarch
    rubygems23-devel-2.5.2.3-1.20.amzn1.noarch

src:
    ruby23-2.3.8-1.20.amzn1.src

x86_64:
    ruby23-devel-2.3.8-1.20.amzn1.x86_64
    ruby23-libs-2.3.8-1.20.amzn1.x86_64
    rubygem23-bigdecimal-1.2.8-1.20.amzn1.x86_64
    rubygem23-io-console-0.4.5-1.20.amzn1.x86_64
    rubygem23-psych-2.1.0.1-1.20.amzn1.x86_64
    rubygem23-json-1.8.3.1-1.20.amzn1.x86_64
    ruby23-debuginfo-2.3.8-1.20.amzn1.x86_64
    ruby23-2.3.8-1.20.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:*

External links

https://alas.aws.amazon.com/ALAS-2018-1113.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Security restrictions bypass

EUVDB-ID: #VU15724