MitM attack in Yaws

1) Use of a broken or risky cryptographic algorithm

EUVDB-ID: #VU47118

Risk: Medium

CVSSv3.1: 4.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-12872

CWE-ID: CWE-327 - Use of a Broken or Risky Cryptographic Algorithm

Exploit availability: No

Description

The vulnerability allows a remote attacker to decrypt sensitive information.

The vulnerability exists due to yaws_config.erl in Yaws loads obsolete TLS ciphers if running on an Erlang/OTP virtual machine with a version less than 21.0. A remote attacker can perform Sweet32 attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Yaws: 1.50 - 2.0.6

External links

http://github.com/erlyaws/yaws/blob/c0fd79f17d52628fcec527da7fa3e788c283c445/src/yaws_config.erl#L2068-L2075
http://github.com/erlyaws/yaws/issues/402
http://github.com/erlyaws/yaws/releases
http://medium.com/@charlielabs101/cve-2020-12872-df315411aa70
http://sweet32.info/

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.