This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker inserts a malicious USB device into a target system. An attacker could then write a malicious binary to disk and execute it.
This update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically.
Microsoft Security Bulletin is available here - https://technet.microsoft.com/en-us/library/security/ms15-085.aspx
Read more on detection guidance here - http://blogs.technet.com/b/srd/archive/2015/08/11/defending-against-cve-2015-1769-a-logical-issue-exploited-via-a-malicious-usb-stick.aspx