** Changed in: gnome-control-center
Status: Unknown => Confirmed
** Changed in: gnome-control-center
Importance: Unknown => Medium
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https://bugs.launchpad.net/bugs/1219337
Title:
Users can change the clock without authenticating, allowing them to
locally exploit sudo.
Status in gnome-control-center:
Confirmed
Status in sudo:
Unknown
Status in policykit-desktop-privileges package in Ubuntu:
Opinion
Status in sudo package in Ubuntu:
Fix Released
Status in policykit-desktop-privileges source package in Precise:
Opinion
Status in sudo source package in Precise:
Triaged
Status in policykit-desktop-privileges source package in Trusty:
Opinion
Status in sudo source package in Trusty:
Triaged
Status in policykit-desktop-privileges source package in Utopic:
Opinion
Status in sudo source package in Utopic:
Won't Fix
Status in policykit-desktop-privileges source package in Vivid:
Opinion
Status in sudo source package in Vivid:
Won't Fix
Bug description:
Under unity and cinnamon, it is possible for a user to turn off
network-syncronized time and then change the time on the system. It is
also possible to "cat /var/log/auth.log" and find the last time a user
authenticated with sudo, along with which pty they used. If a user had
used a terminal and successfully authenticated with sudo anytime in
the past, and left the sudo file in "/var/lib/sudo/<username>/", a
malicious user could walk up to an unlocked, logged in machine and
gain sudo without knowing the password for the computer.
To do this, a user would only need to launch a few terminals, figure
out which pty they were on via "tty", find the an instance in
/var/log/auth.log where sudo was used on that PTY, and set the clock
to that time. Once this is done, they can run (for example) "sudo -s"
and have a full access terminal.
1) This has been observed on Ubuntu 13.04, and may work on other versions.
2) This may have an effect on various window managers, but I confirmed it on
Unity and Cinnamon
3) I expected to have to authenticate when I changed the time and date, as I
do on Gnome and KDE. I also expected to be denied permission to auth.log
4) I was able to change the system time to whatever I wanted, and view
auth.log. This was sufficient to access sudo without having to type my password.
Note: This bug also affects any version of OS X, though the mechanism
is different. Some versions don't require you to authenticate to
change the time through the GUI, but some do. No version I've seen
requires authentication to use the "systemsetup" command, which can
alter the time from the command line. This may be an overall bug in
sudo. Why can I bypass security by changing the time?!
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