Can the Legitimate logonui.exe be used maliciously?

Solved.

Can the logonui.exe be used maliciously? Maybe, but one would still need credentials, it doesn't bypass your Windows password for example. Was it used maliciously in your case? Probably not. Just overly paranoid.

Thank you for replying. Trust me I'm aware I'm overly paranoid and need to stop overly monitoring everything, because I have little knowledge of how computers work it's easy for me to just assume anything that goes wrong is hacker and/or virus related. I'm usually able to just solve any problem I have by googling it and finding other people have the same problem or the same events occurring and I'm able to set aside my paranoia on that issue. This however is slightly different in that i can't find a reason why, but like all other issues i have it's probably nothing.

There are a lot of other accounts on the computer besides just user accounts. The backup process you mention, Windows has a special account just for backing up programs. It is not uncommon for a service to log into a special account to function. Most services Windows runs are part of "Local Service" and or "Local System" accounts.

Thank you for your help.