Denial of service in activestorage gem for Ruby

1) Input validation error

EUVDB-ID: #VU28240

Risk: Medium

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

CVE-ID: CVE-2020-8162

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input in ActiveStorage's S3 adapter. A remote attacker can control the Content-Length of an S3 direct upload URL without receiving a new signature from the server and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

activestorage: 5.2.0 - 6.0.3 rc1

External links

http://snyk.io/vuln/SNYK-RUBY-ACTIVESTORAGE-569602
http://github.com/rails/rails/commit/c0ab9a7d29b84a6ccb1ffa3e8ca1ce61f7a9fbb8
http://groups.google.com/forum/#!topic/rubyonrails-security/PjU3946mreQ
http://hackerone.com/reports/789579

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.