The elevation of privilege is documented in CVE-2019-1378, where Microsoft explains that an attacker can create an account with full user rights, eventually gaining access to install malware to take control of devices.
"There is a privilege vulnerability in Windows 10 Update Assistant in the way it manages permissions", says Microsoft.
“A locally authenticated attacker could run malicious code with elevated system privileges. After successfully exploiting the vulnerability, an attacker could install preletterthem, view, change, or delete data, create new accounts with full user rights.”
Το ελάττωμα ανακαλύφθηκε και αναφέρθηκε στη Microsoft από τον Jimmy Bayne και υπάρχει στον Windows 10 Update Assistant ανεξάρτητα από την version των Windows 10 που έχετε εγκατεστημένη.
As reported on Bleepingcomputer, some computers start running the Windows 10 Update Assistant after the installation of update KB4023814. However, this update is only for devices running Windows 10 version 1803 (April 2018 Update) or later and is supposed to prepare the "ground" for upgrading to Windows 10 to the 1903 version (May 2019 Update).
On the other hand, devices running Update Assistant on Windows 10 on the 1903 version are also vulnerable to attacks if the update was installed manually.
Microsoft has already released a new version of Update Assistant to resolve the vulnerability and recommends all users to install it as soon as possible. The only way to fix the flaw is not to automatic install this new version, at least until the patch is included in some update rollup. Of course you should uninstall the older version:
Microsoft reports that the defect was not publicly disclosed and thus no (yet) exploit has been released. However, you need to update your system.