When one user has mounted a cifs share that requires authentication, another user could mount the same share without knowing the correct password. A way to exploit this would be through mount.cifs if it's installed setuid root. On Red Hat Enterprise Linux, mount.cifs is not root setuid by default. Upstream commits: http://git.kernel.org/linus/4ff67b720c02c36e54d55b88c2931879b7db1cd2 http://git.kernel.org/linus/fc87a40677bbe0937e2ff0642c7e83c9a4813f3d http://git.kernel.org/linus/24e6cf92fde1f140d8eb0bf7cd24c2c78149b6b2
Statement: This issue did not affect the versions of Linux kernel as shipped in Red Hat Enterprise Linux 4, 5, 6, and Red Hat Enterprise MRG as they did not ship mount.cifs with root setuid set. However, as a preventive meaasure, we have addressed this in Red Hat Enterprise Linux 5 and Red Hat Enterprise MRG via https://rhn.redhat.com/errata/RHSA-2011-1386.html and https://rhn.redhat.com/errata/RHSA-2011-1253.html. Red Hat Enterprise Linux 4 is now in Production 3 of the maintenance life-cycle, https://access.redhat.com/support/policy/updates/errata/, therefore the fix for this issue is not currently planned to be included in the future updates.
Another way to mount the share without correct password is when user has sudo privilege to execute /sbin/mount.cifs (even when mount.cifs does not have setuid) Ex. I am "userb". "usera" has already mounted a //server/share. I can execute the following and provide wrong password: [userb@localhost]$ sudo /sbin/mount.cifs //server/share ./localmount -o user=usera,domain=windows_domain
(In reply to comment #4) > Another way to mount the share without correct password is when user has sudo > privilege to execute /sbin/mount.cifs (even when mount.cifs does not have > setuid) > > Ex. I am "userb". "usera" has already mounted a //server/share. > I can execute the following and provide wrong password: > > [userb@localhost]$ sudo /sbin/mount.cifs //server/share ./localmount -o > user=usera,domain=windows_domain That is why I proposed to have this addressed as a preventive measure. Thanks.
This issue has been addressed in following products: MRG for RHEL-6 v.2 Via RHSA-2011:1253 https://rhn.redhat.com/errata/RHSA-2011-1253.html
This issue has been addressed in following products: Red Hat Enterprise Linux 5 Via RHSA-2011:1386 https://rhn.redhat.com/errata/RHSA-2011-1386.html