There is a Group Policy for Internet Explorer users who receive a prompt like this: “I want to complete this action by entering my credentials on the authentic Windows logon screen” followed by “CTRL ALT DEL to enter your details.”
The Group Policy setting is located under Computer Configuration – Administrative Templates – Windows Components – Credential User Interface – Require trusted path for credential entry. This policy is compatible with Windows Vista and newer Windows releases. The policy is defined in the CredUI.admx and CredUI.adml group policy template files.
If you want to prevent this extra level of prompting, set the policy to Disabled or Not Configured.
The associated registry location is: HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\CredUI\EnableSecureCredentialPrompting – I believe the enabled value is 1 and disabled value is 0 (typical for these policy settings).
Please review the following source pages for more on this topic: