Hanno Böck wrote:
> I wanted to point out an issue here with vim swap files that make them
> a security problem.
>
> By default vim creates a file with the name .filename.swp in the same
> directory while editing. They contain the full content of the edited
> file. This usually gets deleted upon exit, but not if vim crashes or
> gets killed (e.g. due to a reboot).
>
> On web servers this can be a severe security risk. One can e.g. scan
> for web hosts that have swap files of PHP configuration files and thus
> expose settings like database passwords. (e.g. wget
> http://example.com/.wp-config.php.swp )
Why would a web server expose and serve such a file? That clearly is
the problem, not that Vim happens to create swap files (and undo and
backup files, depending on your configuration).
You probably also create new files and copies of files that should not
be served. If you care about security, the web server must always use
whitelisting, only serve files that were intentionally made public.
> In a scan of the alexa top 1 million I found ~750 instances of such
> files. I tried to inform affected people as best as I could. I also
> discovered such scans in my own web server logs, so I assume black hats
> are already aware of this and it's actively exploitet.
>
> I was wondering how to best avoid this on my own servers and I first
> thought about saving the swap files to tmp ( with "set directory").
> However on multiuser systems this creates another security problem.
> These files are world readable, thus instead of leaking information to
> the world it's now leaking information to other users on the same
> system. Thus even if one is aware of the issue it's nontrivial to get
> secure settings (I've now worked around this by having per-user tmp
> dirs with secure permissions.)
>
> I think vim should change the behavior of swap files:
> 1. they should be stored in /tmp by default
No, on Linux this is wiped clean on reboot. You lose your work on a
system crash.
> 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).
The permissions are the same as the original file, and that is exactly
how it should be.
> 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)
Infeasible, Vim can't find that file when trying to recover the original
file.
--
BEDEVERE: Oooooh!
LAUNCELOT: No "Aaaaarrrrrrggghhh ... " at the back of the throat.
BEDEVERE: No! "Oooooh!" in surprise and alarm!
"Monty Python and the Holy Grail" PYTHON (MONTY) PICTURES LTD
/// Bram Moolenaar -- b...@moolenaar.net -- http://www.Moolenaar.net \\\
/// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
\\\ an exciting new programming language -- http://www.Zimbu.org ///
\\\ help me help AIDS victims -- http://ICCF-Holland.org ///
--
--
You received this message from the "vim_dev" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php
---
You received this message because you are subscribed to the Google Groups
"vim_dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to vim_dev+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
