annotate org/emacs-password.org @ 73:135fabc13f8a

digital interlibrary loan for articles.
author Robert McIntyre <rlm@mit.edu>
date Sat, 16 Nov 2013 15:16:04 -0500
parents 8a5b6ca53764
children
rev   line source
rlm@9 1 #+title: Password Security in Emacs Terminal Emulators
rlm@9 2 #+author: Robert McIntyre
rlm@9 3 #+email: rlm@mit.edu
rlm@9 4 #+description: emacs terminal password security
rlm@9 5 #+keywords: emacs, password, security, term
rlm@9 6 #+SETUPFILE: ../../aurellem/org/setup.org
rlm@9 7 #+INCLUDE: ../../aurellem/org/level-0.org
rlm@9 8 #+babel: :mkdirp yes :noweb yes :exports both
rlm@9 9
rlm@9 10 I use emacs for everything -- email, programming, document
rlm@9 11 preparation, planning... You name it, I do it! One thing which I use
rlm@9 12 emacs for is terminal emulation, which is where you create a buffer in
rlm@9 13 emacs where you can enter commands as if the buffer were a
rlm@9 14 terminal. Good terminal emulation packages for emacs include
rlm@9 15 =multi-term= and =term=.
rlm@9 16
rlm@10 17 * Watch Out for =view-lossage=!
rlm@9 18 However, if you are going to use terminal emulation in emacs, you have
rlm@9 19 to be careful around "sudo" prompts, and when logging into other
rlm@11 20 servers using ssh, because /the last 300 keystrokes you have typed in
rlm@9 21 emacs are available/ using =C-h l=, a help function in emacs which
rlm@10 22 displays the last keypresses you have typed.
rlm@9 23
rlm@9 24 #+begin_example
rlm@9 25 C-h l runs the command view-lossage, which is an interactive compiled
rlm@9 26 Lisp function in `help.el'.
rlm@9 27
rlm@9 28 It is bound to C-h l, <help> l.
rlm@9 29
rlm@9 30 (view-lossage)
rlm@9 31
rlm@9 32 Display last 300 input keystrokes.
rlm@9 33 #+end_example
rlm@9 34
rlm@9 35 Let's say my password is "sup3r-seekrit#7".
rlm@9 36
rlm@9 37 I open an emacs terminal using =M-x multi-term=, then do the following
rlm@9 38
rlm@9 39 #+begin_example
rlm@9 40 [~] $ ssh rlm@linerva.mit.edu
rlm@9 41 Password:
rlm@9 42
rlm@9 43 Welcome to Linerva, the SIPB Linux dialup for MIT.
rlm@9 44 Linerva runs Debathena on Debian squeeze.
rlm@9 45 http://linerva.mit.edu for more information
rlm@9 46 blanche linerva-announce -a $USER # for outage announcements
rlm@9 47 linerva@mit.edu (not IS&T) for questions and bug reports
rlm@9 48
rlm@9 49 Last login: Mon Mar 4 12:53:23 2013 from ella.csail.mit.edu
rlm@9 50 rlm@dr-wily:~$ exit
rlm@9 51 logout
rlm@9 52 Connection to linerva.mit.edu closed.
rlm@9 53 #+end_example
rlm@9 54
rlm@9 55 Now, when I type =C-h l=, I can see this:
rlm@9 56
rlm@9 57 #+begin_example
rlm@9 58 s s h SPC r l m @ l i n e r v a . m i t . e d u <return>
rlm@9 59 s u p 3 r - s e e k r i t # 7 <return> e x i t C-h l
rlm@9 60 #+end_example
rlm@9 61
rlm@9 62 Needless to say, this can be a security vulnerability.
rlm@9 63
rlm@9 64 * Solutions to this problem
rlm@9 65
rlm@9 66 - If you don't ever type your password into an emacs terminal buffer,
rlm@9 67 then you are not at risk. This can be accomplished by using ssh
rlm@10 68 keyfiles or Kerberos for connecting to remote servers, and by
rlm@9 69 enabling passwordless sudo.
rlm@9 70
rlm@9 71 - You can disable emacs keylogging, though you then won't be able to
rlm@9 72 use the =view-lossage= command anymore.
rlm@9 73
rlm@9 74 - If there's no way for an attacker to get into your emacs process,
rlm@9 75 then your passwords are safe. Still, you run the risk of someone
rlm@9 76 physically near your computer using this method to view your
rlm@9 77 password, as well as inadvertently exposing your password when
rlm@9 78 showing someone what =view-lossage= does!
rlm@9 79
rlm@9 80 * Source Listing
rlm@9 81 #+html: <ul> <li> <a href="../org/emacs-password.org">This org file</a> </li> </ul>
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