[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 30 Jun 2015 23:30:06 +0200
From: vladz <vladz@...zero.fr>
To: oss-security@...ts.openwall.com
Subject: Re: Question about world readable config files and
commented warnings
On Tue, Jun 30, 2015 at 08:31:08AM -0600, Kurt Seifried wrote:
> From a developer perspective I somewhat agree, however I'm looking at
> this from a vendor perspective where we do control the chmod, easily
> (RPM spec file).
I don't know if this is relevant, but I also regularly find applications
that, during their installation phases, set the correct permissions to
sensitive files (600 for instance) but in a insecure manner, i.e. they:
1) create the file (perms will depend on root umask, usually 022)
2) restrict its permissions (chmod 600)
3) open the file and write sensitive content in it
I won't paraphrase this post [1], but chmod 600 on a file isn't sufficient
to preserve a file content on a multiuser system: a local user can open the
file in read-only right after 1) to obtain a file descriptor, and use it
for later content disclosure after 3).
We all know that a better way to create the file would be to set the
adequate umask first. But the above steps can be found in initialization
and installation scripts (I can share a non-exhaustive list if wished). I
also wouldn't recommend the use of "-m 600" in the "install" command as it
has the same problem:
# touch f1
# strace install -m 600 f1 f2
[...]
open("f2", O_WRONLY|O_CREAT|O_EXCL, 0644) = 4 // here f2 is readable
chmod("f2", 0600) = 0
Regards,
vladz.
[1] http://www.openwall.com/lists/oss-security/2013/08/20/13
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
