Microsoft has quelled any fears that Windows Update was compromised yesterday after a highly suspicious patch was delivered to devices running Windows 7 across the globe.

The 'important' update in question, around 4.3 MB in size and dated October 1, immediately raised red flags due to its nonsense name and randomly-generated accompanying data. However a Microsoft spokesperson has since confirmed the company "incorrectly published a test update and are in the process of removing it."

For most users, the update failed to install on their system, however one Ars Technica reader reportedly managed to successfully install the patch, which led to general system instability and crashes. The update was only delivered to consumer versions of Windows 7, so anyone running Windows 10 avoided any issues relating to Microsoft's test.

Had Windows Update been compromised, it would have been a very serious issue as an attacker could easily and automatically deploy malware to every machine running Windows. Some malware has been able to hijack Windows Update and propagate through local networks, but an attacker is yet to compromise Microsoft's own update servers.

By now the update should be removed from Windows Update and Windows 7 machines around the world, but if it hasn't disappeared from Update just yet, it's advised that you don't attempt to install the patch in case it causes issues with your system.