Red Hat Bugzilla – Bug 910082
CVE-2013-5745 vino: denial of service flaw
Last modified: 2015-11-24 10:35:24 EST
Description of problem:
I have vino set to require a password. The system is on a publicly accessible machine. One morning I arrived to find / full and vino-server using inordinate amounts of CPU. In trying to find free space I also noticed that soon after freeing space, it would get used up. (Which is when I looked at what processes were running and found vino using too much CPU for not having a client connected).
In the end I found that ~/.cache/gdm/session.log was 669G. A message was repeated "AM Authentication deferred - ignoring client message".
It was repeating 80 000 per second in the log file.
Thus Vino should introduce some form of rate limiting or other related features to help avoid this situation. It would also be nice if it could detect something like this and add a setting for blacklisting IPs that make more than X requests per second or some such. I realize though that some of that could be done via a firewall so perhaps not on that second part. However rate limiting the logs would be very useful to avoid this situation
Not easy to reproduce as I don't know exactly what was making the requests to vino.
This bug is fixed upstream, and the patch to fix it is simple and can be applied to the version in Fedora:
Also, this was given the name CVE-2013-5745.
Created vino tracking bugs for this issue:
Affects: fedora-all [bug 1008661]
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Red Hat Enterprise Linux 6
Via RHSA-2013:1452 https://rhn.redhat.com/errata/RHSA-2013-1452.html
vino-3.8.1-3.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.