Hi Mark - I've taken a look at the details in this bug, the upstream sudo bug, the /r/linux thread, and the upstream sudo fix. I appreciate and respect your thoroughness.
After taking all of the details into account, I consider this issue to be low severity due to the mitigating factors involved. Specifically, I don't see a way for an attacker, without physical access, to use an arbitrary code execution vulnerability in combination with the issue that you've described in this bug to elevate his/her privileges. Considering this, the attack requires an admin user leave his/her desktop session unlocked and for an attacker to come across this unlocked desktop session. Since there are many different ways to attack an unlocked desktop session, best security practices dictate all users lock their screens when not at their computer. We will fix this issue in the next Ubuntu release (15.10) by including sudo 1.8.10 or newer. Due to the issue’s low severity and considering our practice of prioritizing resources on publishing security updates that fix issues of greater security impact, we may fix this issue in stable releases of Ubuntu in the future if another sudo vulnerability of higher severity is found or if new details emerge regarding this issue. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to sudo in Ubuntu. https://bugs.launchpad.net/bugs/1219337 Title: Users can change the clock without authenticating, allowing them to locally exploit sudo. Status in Cinnamon: New Status in sudo: Unknown Status in Unity: Invalid Status in policykit-desktop-privileges package in Ubuntu: Opinion Status in sudo package in Ubuntu: Confirmed Status in policykit-desktop-privileges source package in Precise: Opinion Status in sudo source package in Precise: Confirmed Status in policykit-desktop-privileges source package in Trusty: Opinion Status in sudo source package in Trusty: Confirmed Status in policykit-desktop-privileges source package in Utopic: Opinion Status in sudo source package in Utopic: Confirmed Status in policykit-desktop-privileges source package in Vivid: Opinion Status in sudo source package in Vivid: Confirmed 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?! To manage notifications about this bug go to: https://bugs.launchpad.net/cinnamon-desktop/+bug/1219337/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
