Vulnerability identifier: #VU32366

Vulnerability risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2015-4020

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Ruby
Universal components / Libraries / Scripting languages

Vendor: Ruby

Description

The vulnerability allows a remote non-authenticated attacker to manipulate data.

RubyGems 2.0.x before 2.0.17, 2.2.x before 2.2.5, and 2.4.x before 2.4.8 does not validate the hostname when fetching gems or making API requests, which allows remote attackers to redirect requests to arbitrary domains via a crafted DNS SRV record with a domain that is suffixed with the original domain name, aka a "DNS hijack attack." NOTE: this vulnerability exists because to an incomplete fix for CVE-2015-3900.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Ruby: 2.0.0 - 2.4.7

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External links
http://blog.rubygems.org/2015/06/08/2.2.5-released.html
http://blog.rubygems.org/2015/06/08/2.4.8-released.html
http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
http://www.securityfocus.com/bid/75431
http://github.com/rubygems/rubygems/commit/5c7bfb5
http://puppet.com/security/cve/CVE-2015-3900
http://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-009/?fid=6478
http://www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/

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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.