[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <c5658eb7-b673-0543-8104-47e35f5a18a0@lighttpd.net>
Date: Tue, 31 Oct 2017 13:50:36 +0100
From: Stefan Bühler <stbuehler@...httpd.net>
To: oss-security@...ts.openwall.com
Subject: Re: Fw: Security risk of vim swap files
On 10/31/2017 01:37 PM, Solar Designer wrote:
> On Tue, Oct 31, 2017 at 01:23:52PM +0100, Hanno B??ck wrote:
>> I think vim should change the behavior of swap files:
>> 1. they should be stored in /tmp by default
>> 2. they should have secure permissions (tmp file security is
>> a tricky thing and needs careful consideration to avoid symlink attacks
>> and the like, but there are dedicated functions for this like mkstemp).
>> 3. Ideally they also shouldn't leak currently edited filenames (e.g.
>> they shouldn't be called /tmp/.test.txt.swp, but more something
>> like /tmp/.vim_swap.123782173)
>
> Out of these, I think only 2 should be done: the files should be mode
> 0600 or 0400 even if the original file's permissions and/or the umask
> are more relaxed.
>
> 1 and 3 go against intended use for these files - recovery of an edit in
> progress if the editor or the entire system crashes (and comes back up
> e.g. after a power-cycle). /tmp contents might not survive a reboot,
> and randomized filenames would prevent vim itself from detecting the
> problem and offering recovery, which it does now.
You could keep the .test.txt.swp file, but make it a symlink and encode
information where to find the real swap file (/var/tmp/, /tmp, ...) in
the symlink.
It shouldn't link directly to the swap file, but perhaps look like
"swap:///var/tmp/.vim_swap.random_id".
Instead of a symlink you could of course just create a normal text file
with the real swap filename in it, but then it might be easier for an
attacker to find the real filename and read that file.
cheers,
Stefan
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.
