Secure attention key
A secure attention key (SAK) or secure attention sequence (SAS)[1] is a special key or key combination to be pressed on a computer keyboard before a login screen which must, to the user, be completely trustworthy. The operating system kernel, which interacts directly with the hardware, is able to detect whether the secure attention key has been pressed. When this event is detected, the kernel starts the trusted login processing.
The secure attention key is designed to make login spoofing impossible, as the kernel will suspend any program, including those masquerading as the computer's login process, before starting a trustable login operation.
Examples
Some examples are:
- Ctrl+Alt+Delete for Windows NT.[1][2]
- Alt+SysRq+K default sequence for Linux.[3] Not a true C2-compliant SAK.[4]
- ⇧ Shift+Stop for PLATO IV in the 1970s.[5]
See also
References
- Microsoft. "S (Security Glossary) - Win32 apps | Microsoft Learn". Retrieved 2023-04-02.
- "Secure Attention Sequence (SAS) - Network Encyclopedia". Retrieved 2023-04-02.
- Andrew Morton (2001-03-18). "Linux 2.4.2 Secure Attention Key (SAK) handling". Linux Kernel Organization. Retrieved 2011-05-30.
- "Linux Magic System Request Key Hacks". kernel.org. 2013-08-12. Retrieved 2017-05-21.
- Control Data Corporation (1981-04-30). "PLATO User's Guide" (PDF). Retrieved 2023-04-21.
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