Signature validation bypass in OpenDMARC

1) Input validation error

EUVDB-ID: #VU21256

Risk: Medium

CVSSv3.1: 4.6 [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-2019-16378

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 OpenDMARC implementation when processing emails with multiple "From:" addresses in a DKIM signed multi-from message. A remote attacker can create a specially crafted email message and bypass signature validation.

Successful exploitation of this vulnerability may allow an attacker to bypass implemented anti-spam measures.

Mitigation

Install update from vendor's website.

Vulnerable software versions

OpenDMARC: 1.3.2 - 1.3.3

External links

http://www.openwall.com/lists/oss-security/2019/09/17/2
http://github.com/trusteddomainproject/OpenDMARC/pull/48
http://seclists.org/bugtraq/2019/Sep/36
http://www.openwall.com/lists/oss-security/2019/09/11/8
http://github.com/trusteddomainproject/OpenDMARC/blob/master/SECURITY/CVE-2019-16378

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.