# HG changeset patch
# User Robert McIntyre <rlm@mit.edu>
# Date 1363091461 0
# Node ID 8db204acd089de3d54a2e857c3fa210ddb408be4
# Parent  5676533b82d8c58261062e9743b58303844cb39d
emacs password concerns.

diff -r 5676533b82d8 -r 8db204acd089 org/emacs-password.org
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org/emacs-password.org	Tue Mar 12 12:31:01 2013 +0000
@@ -0,0 +1,86 @@
+#+title: Password Security in Emacs Terminal Emulators
+#+author: Robert McIntyre
+#+email: rlm@mit.edu
+#+description: emacs terminal password security
+#+keywords: emacs, password, security, term
+#+SETUPFILE: ../../aurellem/org/setup.org
+#+INCLUDE: ../../aurellem/org/level-0.org
+#+babel: :mkdirp yes :noweb yes :exports both
+
+I use emacs for everything -- email, programming, document
+preparation, planning... You name it, I do it! One thing which I use
+emacs for is terminal emulation, which is where you create a buffer in
+emacs where you can enter commands as if the buffer were a
+terminal. Good terminal emulation packages for emacs include
+=multi-term= and =term=.
+
+* Watch Out for =view-lossave=!
+However, if you are going to use terminal emulation in emacs, you have
+to be careful around "sudo" prompts, and when logging into other
+servers using ssh, because /the last 300 keystrokes you have types in
+emacs are available/ using =C-h l=, a help function in emacs which
+displays the last keypresses you have types.
+
+#+begin_example
+C-h l runs the command view-lossage, which is an interactive compiled
+Lisp function in `help.el'.
+
+It is bound to C-h l, <help> l.
+
+(view-lossage)
+
+Display last 300 input keystrokes.
+#+end_example
+
+Let's say my password is "sup3r-seekrit#7".
+
+I open an emacs terminal using =M-x multi-term=, then do the following
+
+#+begin_example
+[~] $ ssh rlm@linerva.mit.edu
+Password: 
+
+Welcome to Linerva, the SIPB Linux dialup for MIT.
+Linerva runs Debathena on Debian squeeze.
+ http://linerva.mit.edu                           for more information
+ blanche linerva-announce -a $USER          # for outage announcements
+ linerva@mit.edu              (not IS&T) for questions and bug reports
+
+Last login: Mon Mar  4 12:53:23 2013 from ella.csail.mit.edu
+rlm@dr-wily:~$ exit
+logout
+Connection to linerva.mit.edu closed.
+#+end_example
+
+Now, when I type =C-h l=, I can see this:
+
+#+begin_example
+s s h SPC r l m @ l i n e r v a . m i t . e d u <return>
+s u p 3 r - s e e k r i t # 7 <return> e x i t C-h l
+#+end_example
+
+Needless to say, this can be a security vulnerability.
+
+* Solutions to this problem
+
+ - If you don't ever type your password into an emacs terminal buffer,
+   then you are not at risk. This can be accomplished by using ssh
+   keyfiles or kereberos for connecting to remote servers, and by
+   enabling passwordless sudo.
+
+ - You can disable emacs keylogging, though you then won't be able to
+   use the =view-lossage= command anymore.
+
+ - If there's no way for an attacker to get into your emacs process,
+   then your passwords are safe. Still, you run the risk of someone
+   physically near your computer using this method to view your
+   password, as well as inadvertently exposing your password when
+   showing someone what =view-lossage= does!
+
+* Source Listing
+#+html: <ul> <li> <a href="../org/emacs-password.org">This org file</a> </li> </ul>
+
+    
+
+
+