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Re: CVE request: mumble local information disclosure
From: Kurt Seifried <kseifried () redhat com>
Date: Thu, 16 Feb 2012 16:05:26 -0700

On 02/16/2012 07:35 AM, Ludwig Nussel wrote:
Vincent Danen wrote:
It was discovered that mumble created its database file
(~/.local/share/data/Mumble/.mumble.sqlite) with insecure world-readable
permissions.  If the user had (non-default) permissions on their home
directory, another local user could obtain password and configuration
settings from the database file.

It certainly makes sense for cautios applications to make sure sensitive
settings have restricted access permissions. Question is whether it is
actually a vulnerability if they don't. Quoting the XDG specĀ¹

We can't rely upon file permissions being done safely/properly, just
like we can't rely upon proper firewalls/etc for network services that
"should" be internal only but sometimes are not (e.g.
SMB/CIFS/NFS/etc.), There are often very legitimate cases for not having
a firewall, world readable home dir, etc. The whole onion (multi-layered
security) approach and so forth means we classify a lot more things as
security vulns than is perhaps strictly necessary, but in the long run
leads to safer and more robust systems.

| If, when attempting to write a file, the destination directory is
| non-existant an attempt should be made to create it with permission
| 0700. If the destination directory exists already the permissions should
| not be changed.

So it could be argued that mumble just relied on the specification that
already mandates restrictive permissions on ~/.config.

The specifications might be wrong, they might be incomplete, they might
be interpreted incorrectly, they might be implemented incorrectly, etc.

The program that is supposed to create ~/.config on login had a bug that
made the dir 755 in violation of the specĀ². Fixing the permissions is
not allowed according to the spec though ...


[1] http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
[2] https://bugs.freedesktop.org/show_bug.cgi?id=36773

Kurt Seifried Red Hat Security Response Team (SRT)

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