Remote code execution in Bundler

1) Insufficient verification of data authenticity

EUVDB-ID: #VU55666

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-36327

CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to insufficient verification of data authenticity in Bundler, when  choosing a dependency source. The application selects a dependency source based on the highest gem version number, which means that a rogue gem found at a public source may be chosen, even if the intended choice was a private gem that is a dependency of another private gem that is explicitly depended on by the application.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

bundler: 1.6.0 - 2.2.17

External links

http://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24105
http://github.com/rubygems/rubygems/issues/3982
http://bundler.io/blog/2021/02/15/a-more-secure-bundler-we-fixed-our-source-priorities.html
http://mensfeld.pl/2021/02/rubygems-dependency-confusion-attack-side-of-things/
http://www.zofrex.com/blog/2021/04/29/bundler-still-vulnerable-dependency-confusion-cve-2020-36327/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWXHK5UUHVSHF7HTHMX6JY3WXDVNIHSL/

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.