what is the security benefit of requiring users to press CTRL-ALT-DEL to logon?

[Special K]

There is an option in winNT/XP to require users to press CTRL-ALT-DEL to bring up the logon menu. In the settings where you enable it, it just says it is used for extra security or something. What exactly is the purpose of logging on this way, and how does it increase security?

 

[Tiger]

It requires positive action from the user rather than automatically logging in at boot.

 

[Nothinman]

It requires positive action from the user rather than automatically logging in at boot.

You can be required to login without hitting c+a+d.

MS says it's because c+a+d is hard coded and bound by winlogin as the only process that can respond to it, so if you hit c+a+d you're 100% sure you're getting MS' Gina to authenticate to and not putting your password into some trojan. But, noone pays attention to that stuff and puts their password into any box that asks for it, so it's a moot point.

 

[ScottMac]

I believe the intention is that hitting ctrl-alt-del would interrupt any spoofing application (i.e., a fake login screen) used to gather usernames and passwords.

FWIW

Scott

 

[VirtualLarry]

Originally posted by: ScottMac
I believe the intention is that hitting ctrl-alt-del would interrupt any spoofing application (i.e., a fake login screen) used to gather usernames and passwords.

FWIW

Scott

Yes, the same reason that VMS/VAX suggests using CTRL+C at the terminal to bring up the logon prompt, because at the very least, a user-mode application running will display some sort of message on the terminal, even if it traps CTRL+C, and will break out of the program if it doesn't trap it. (NT was designed based on VMS.)

 

[TonyRic]

When Windows NT was being cobbled together from Windows 3.x and OS/2, MS trapped C+A+D for security reasons. Since CAD can be spoofed in software, MS decided to trap it so that to system cannot be rebooted by issuing a CAD in software. Before trapping it, CAD would reboot without user intervention and cause potential data loss and possibly start any trojan apps installed without user authorization. This was all required to receive gov't C2 Security Certification (Something MS only received as long as the computer was not plugged into a network of any kind). Most in the industry derrided MS for doing it, and some still do.