Vulnerability identifier: #VU25586

Vulnerability risk: Low

CVSSv3.1: 7.9 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2020-8793

CWE-ID: CWE-264

Exploitation vector: Local

Exploit availability: Yes

Vulnerable software:
OpenSMTPD
Server applications / Mail servers

Vendor: OpenBSD

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to the application does not drop privileges when executing the "/usr/sbin/smtpctl" application with  a "-bi" command-line argument. A local user can leverage this behavior and use a specially crafted hardlink to execute arbitrary code on the system with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSMTPD: 5.0 - 20121113231010p1

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External links
http://seclists.org/oss-sec/2020/q1/86
http://ftp.openbsd.org/pub/OpenBSD/patches/6.6/common/021_smtpd_envelope.patch.sig

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.