Editing Secure attention key

A '''secure attention key''' ('''SAK'''), '''special attention key''',<ref>{{Cite web|url=https://mastodon.social/@pid_eins/113441346864726148|title=Lennart Poettterin on Mastodon|author=Lennart Poettering|date=2024-11-07|accessdate=2025-03-26}}</ref> or '''secure attention sequence''' ('''SAS''')<ref name=ms-sas>{{Cite web|url=https://learn.microsoft.com/en-us/windows/win32/secgloss/s-gly#_SECURITY_SECURE_ATTENTION_SEQUENCE_GLY|title=S (Security Glossary) - Win32 apps {{!}} Microsoft Learn|author=[[Microsoft]]|date=7 January 2021 |access-date=2023-04-02}}</ref> is a special key, [[Keyboard shortcut|key combination]] or sequence to be pressed on a [[computer keyboard]] before a [[login]] screen which must, to the user, be completely trustworthy. The  [[operating system]] [[kernel (operating system)|kernel]], which interacts directly with the hardware, or [[Init|init system]] is able to detect whether the secure attention key has been pressed. When this event is detected, the trusted login processing is started.

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:
* {{key press|Ctrl|Alt|Shift|Esc}}: Introduced in [[systemd]] v257 as a more reliable SAK for [[Linux]] [[Linux distributions|distributions]] but may require support from the currently running [[Desktop Environment|desktop environment]].<ref>{{Cite web|url=https://mastodon.social/@pid_eins/113441386934639615|title=Lennart Poettterin on Mastodon|author=Lennart Poettering|date=2024-11-07|accessdate=2025-03-26}}</ref> It is implemented as of gdm ([[GNOME]] [[Login manager|display manager]]) 47.<ref>{{Cite web|url=https://gitlab.gnome.org/GNOME/gdm/-/commit/969ffab4855b12d6901fc06d1a844583f294fb50|title=
47.rc|author=Ray Strode|date=2024-09-11|accessdate=2025-03-26}}</ref>
* {{key press|Ctrl|Alt|Backspace}} on [[X Window System]] immediately kills the X server (although the key combination can be disabled<ref>{{Cite web|url=https://wiki.ubuntu.com/XorgCtrlAltBackspace|title=XorgCtrlAltBackspace|author=dhcp198-158|date=2010-06-12|accessdate=2025-03-26}}</ref>) and can be used to quickly and easily get back to the login prompt.<ref>{{Cite web|url=https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/enable-ctrl-alt-backspace#enable-ctrl-alt-backspace|title=Enabling the Ctrl+Alt+Backspace Shortcut|accessdate=2025-03-26}}</ref>
* [[Magic SysRq key|{{key press|Alt|SysRq|K}}]] default sequence for [[Linux]].<ref name="Morton2001">{{cite web|url=https://www.kernel.org/doc/Documentation/SAK.txt|title=Linux 2.4.2 Secure Attention Key (SAK) handling|author=Andrew Morton|author-link=Andrew Morton (computer programmer)|date=2001-03-18|publisher=[[Linux Kernel]] Organization|accessdate=2011-05-30}}</ref> Not a true [[Trusted Computer System Evaluation Criteria|C2-compliant]] SAK.<ref name=":0">{{cite web
| url=https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html
| title=Linux Magic System Request Key Hacks
| date=2013-08-12
| publisher=[[kernel.org]]
| accessdate=2017-05-21
}}</ref>
* {{key press|Ctrl|X}} then {{key press|Ctrl|R}} on [[AIX]],<ref>{{Cite web|url=https://www.ibm.com/docs/en/aix/7.3?topic=options-using-secure-attention-key|title=Using the Secure Attention Key|author=IBM|website=[[IBM]] |date=2025-02-03|accessdate=2025-03-26}}</ref> but it can be disabled.<ref>{{Cite web|url=https://www.ibm.com/docs/en/aix/7.3?topic=options-configuring-secure-attention-key|title=Configuring the Secure Attention Key|author=IBM|website=[[IBM]] |date=2025-02-03|accessdate=2025-03-26}}</ref><ref>{{Cite web|url=https://www.ibm.com/docs/en/sig-and-i/10.0.2?topic=information-aix-default-attributes|title=AIX Default Attributes|author=IBM|website=[[IBM]] |date=2025-02-20|accessdate=2025-03-26}}</ref>
* {{key press|Shift|Stop}} for [[PLATO (computer system)|PLATO IV]] in the 1970s.<ref>{{Cite web|url=http://www.bitsavers.org/pdf/cdc/plato/97405900C_PLATO_Users_Guide_Apr81.pdf|title=PLATO User's Guide|author=Control Data Corporation|date=1981-04-30|accessdate=2023-04-21}}</ref>
* [[Control-Alt-Delete#Windows NT family|{{Keypress|Ctrl|Alt|Delete}}]] for Windows NT.<ref name=ms-sas/><ref>{{Cite web|url=https://networkencyclopedia.com/secure-attention-sequence-sas/|title=Secure Attention Sequence (SAS) - Network Encyclopedia|date=6 January 2020 |access-date=2023-04-02}}</ref>

==See also==
* [[Control-Alt-Delete]]
* [[Magic SysRq key]]
* [[Break key]]

==References==
{{Reflist}}

{{DEFAULTSORT:Secure Attention Key}}
[[Category:Computer security procedures]]
[[Category:Computer access control]]


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