Some computers can be set to require the SAS when logging to the account or run applications with elevation (using different policy settings than the above). The "Disable or enable software secure attention sequence" policy was created for sending of Ctrl-Alt-Del (SAS) on the remote computer. You can enable/restrict/disable this by properly setting this policy. This of course makes sense if the SAS is enabled.
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Why SAS is good for security?
When for example, you execute the program that requires elevation, then when using this setting, you first will see the SAS alert, press OK, and then press CTRL+ALT+DEL to see UAC window. The malware cannot replicate this behavior (cannot do CTRL+ALT+DEL programmatically). This is an additional security when the malware is going to fool you showing the fake UAC alert and next stealing your admin password.
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