4 ms·

Fun fact: Login spoofing like this is why, from Windows NT on, users have had to first enter a security context with Ctrl+Alt+Del. https://en.wikipedia.org/wik

by samch 3y ago

Fun fact: Login spoofing like this is why, from Windows NT on, users have had to first enter a security context with Ctrl+Alt+Del. https://en.wikipedia.org/wiki/Control-Alt-Delete https://en.wikipedia.org/wiki/Control-Alt-Delete

gumby 3y ago
an approach that goes back the the rainbow books, at least. There was some scheme to use the "break" key on the teletype for this (maybe in Multics, or OS/360 perhaps?) but I have no idea if it was ever implemented. For those who don't remember, "break" was not an ASCII character but a literal long unmaskable pause in transmission, and couldn't be generated in software or by reading the paper tape punch, nor could it be read on the host side into an input buffer as it wasn't a character.
- TimTheTinker 3y ago
  In MS-DOS, Ctrl+Break could be simulated through ASCII character 0x03. Literally, hit Alt+3 and it would respond the same way. The sysadmin for my high school computer lab had written a text-mode DOS login screen that would start Windows 3.11 for workgroups after the user logged in. A few of us kids figured out we could just Ctrl+Break out of it and install/play DOOM, Descent 2, etc. He wised up and wrote a trap for the Ctrl+Break sequence, but I discovered the Alt+3 trick and we continued on our merry way. I don't think he ever figured out how we did it. (We also hid our games inside a directory named Alt+255, which appeared as a space. A single space was not allowed as a directory name, so it felt like magic to us.)
  - chx 3y ago
    Ha yes, name your TSR keylogger REMalt+255.COM , put it into AUTOEXEC.BAT , it looks like an innocent comment.
- eichin 3y ago
  The magic words being "Secure Attention Key" (on multics in particular, it was specifically caught by the Front End Processor, so nothing in the OS could interfere by (for example) catching the signal and printing a fake login prompt, becauase it was literally a separate computer handling the request...)
deleted 3y ago
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by samch 3y ago

gumby 3y ago

an approach that goes back the the rainbow books, at least. There was some scheme to use the "break" key on the teletype for this (maybe in Multics, or OS/360 perhaps?) but I have no idea if it was ever implemented. For those who don't remember, "break" was not an ASCII character but a literal long unmaskable pause in transmission, and couldn't be generated in software or by reading the paper tape punch, nor could it be read on the host side into an input buffer as it wasn't a character.

TimTheTinker 3y ago
In MS-DOS, Ctrl+Break could be simulated through ASCII character 0x03. Literally, hit Alt+3 and it would respond the same way. The sysadmin for my high school computer lab had written a text-mode DOS login screen that would start Windows 3.11 for workgroups after the user logged in. A few of us kids figured out we could just Ctrl+Break out of it and install/play DOOM, Descent 2, etc. He wised up and wrote a trap for the Ctrl+Break sequence, but I discovered the Alt+3 trick and we continued on our merry way. I don't think he ever figured out how we did it. (We also hid our games inside a directory named Alt+255, which appeared as a space. A single space was not allowed as a directory name, so it felt like magic to us.)
- chx 3y ago
  Ha yes, name your TSR keylogger REMalt+255.COM , put it into AUTOEXEC.BAT , it looks like an innocent comment.
eichin 3y ago
The magic words being "Secure Attention Key" (on multics in particular, it was specifically caught by the Front End Processor, so nothing in the OS could interfere by (for example) catching the signal and printing a fake login prompt, becauase it was literally a separate computer handling the request...)

deleted 3y ago

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