[VU:567764] MySQL for Windows is vulnerable to privilege escalation due to OPENSSLDIR location

Overview

MySQL for Windows contains a privilege escalation vulnerability due to the use of an OPENSSLDIR variable that specifies a location where an unprivileged Windows user can create files.

Description

CVE-2021-2307

MySQL includes an OpenSSL component that specifies an OPENSSLDIR variable as a subdirectory of /build_area/. On the Windows platform, this path is interpreted as C:\build_area. MySQL contains a privileged service that uses this OpenSSL component. Because unprivileged Windows users can create subdirectories off of the system root, a user can create the appropriate path to a specially-crafted openssl.cnf file to achieve arbitrary code execution with SYSTEM privileges.

Impact

By placing a specially-crafted openssl.cnf in a C:\build_area subdirectory, an unprivileged user may be able to execute arbitrary code with SYSTEM privileges on a Windows system with the vulnerable MySQL software installed.

Solution

Apply an update

This vulnerability is addressed in the MySQL Windows installer version 8.0.24 and 5.7.34.

Create a C:\build_area directory

In cases where an update cannot be installed, this vulnerability can be mitigated by creating a C:\build_area directory and restricting ACLs to prevent unprivileged users from being able to write to this location.

Acknowledgements

This vulnerability was reported by Will Dormann of the CERT/CC.

This document was written by Will Dormann.