I had the same screen for a moment, clicked the back arrow on my browser thinking I had accidentally clicked something. It then logged me on to view my webmail. I tried to signout using the icon on the webmail toolbar, but it just keeps reloading the page. I had to close out of the browser completely, Opened up browser again, clicked my bookmark for Webmail, logged in like normal, but it still won't let me sign out.
This is part of the recent maintenance to the mail platform, not malware. It was likely asking you to update your secret question/answer if it was not completed and/or incomplete as a security measure. There were a couple issues that needed to be corrected related to logging in after the maintenance, but everything should be working properly now.