On 2017-05-29 10:39, Marco Atzeri wrote:
On 29/05/2017 07:23, Houder wrote:
[snip]
... because, that is, I think, what I am seeing:
- the userid of child sshd is still 'cyg_server' ...
- and I get an elevated shell when I login ...
Not what I expected ...
Gr. Henri
Hi Houder,
please read the last Announcement
https://sourceware.org/ml/cygwin-announce/2017-03/msg00028.html
[snip]
It seems you misunderstood the communication:
- the possibility to NOT use "privilege separation" is deprecated
- "privilege separation" will became mandatory
Hi Marco,
Sorry for the misunderstanding. Yes, to my knowledge, PS, privilege
separation, is now mandatory (using a new mechanism under Linux [1]).
[1] sandboxing?
Because of PS, I expect to see an UNprivileged sshd process talking
to the user process (where the ssh command has been executed).
But above all, I expect an UNelevated shell when I login in ...
However, what I get after login (after providing my credentials) is
an ELEVATED shell (yes, Administrators is part of the group set).
Now I wonder if this happens because I do NOT observe PS.
Look below, please ... After executing the ssh command, ssh asks for
my credentials ... in stead of providing my credentials, I execute
the ps command in a second terminal. To my surprise, the grandchild
of the listener is executed using "cyg_server" and not "sshd" ...
Currently, I am looking at:
https://cygwin.com/cygwin-ug-net/ntsec.html#ntsec-setuid-overview
Regards,
Henri
-----
- pre-authentication:
Shell 1:
64-@@ ssh -p 222 -l Henri 192.168.178.15
Enter passphrase for key '/home/Henri/.ssh/id_rsa': <==== passphrase not
yet entered
Shell 2: (observer)
64-@@# ps -af
UID PID PPID TTY STIME COMMAND
Henri 2308 4356 pty0 11:01:41 /usr/bin/ssh
Henri 5092 176 pty1 11:01:58 /usr/bin/ps
Henri 4356 3744 pty0 10:57:56 /usr/bin/bash
Henri 3744 1 ? 10:57:50 /usr/bin/mintty-273
Henri 176 4604 pty1 10:58:21 /usr/bin/bash
cyg_serv 4992 2476 ? 11:01:03 /usr/sbin/sshd
privileged listener
cyg_serv 2476 1 ? 11:01:03 /usr/bin/cygrunsrv
Henri 4604 1 ? 10:58:21 /usr/bin/mintty-273
cyg_serv 1496 3032 ? 11:01:42 /usr/sbin/sshd
should be using sshd as userid
cyg_serv 3032 4992 ? 11:01:42 /usr/sbin/sshd
privileged monitor (child of listener)
- post-authentication:
Shell 1:
64-@@ ssh -p 222 -l Henri 192.168.178.15
Enter passphrase for key '/home/Henri/.ssh/id_rsa': <==== passphrase has
been entered
Last login: Mon May 29 10:07:00 2017 from 192.168.178.15
64-@@# <===== ///// PROBLEM: this shell is ELEVATED /////
Shell 2: (observer)
64-@@# ps -af
UID PID PPID TTY STIME COMMAND
Henri 2496 3032 pty3 11:02:31 /usr/bin/bash
remote shell (but it is an elevated shell! ?????)
Henri 2308 4356 pty0 11:01:41 /usr/bin/ssh
Henri 4356 3744 pty0 10:57:56 /usr/bin/bash
Henri 3744 1 ? 10:57:50 /usr/bin/mintty-273
Henri 176 4604 pty1 10:58:21 /usr/bin/bash
cyg_serv 4992 2476 ? 11:01:03 /usr/sbin/sshd
privileged listener
Henri 4996 176 pty1 11:06:05 /usr/bin/ps
cyg_serv 2476 1 ? 11:01:03 /usr/bin/cygrunsrv
Henri 4604 1 ? 10:58:21 /usr/bin/mintty-273
cyg_serv 3032 4992 ? 11:01:42 /usr/sbin/sshd
privileged monitor (child of listener)
=====
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