On Tue, Oct 31, 2017 at 11:30 AM, Hanno Böck <ha...@hboeck.de> wrote: > Hi, > > 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 ) > > 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 > 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) > > -- > Hanno Böck > https://hboeck.de/
Isn't /tmp deleted at every bootup? If it is, or on the systems where it is, this makes it useless for files whose chief utility is to allow recovery after a program or system crash. IMHO, the kind of considerations in Herrn Böcks message should not be handled at Vim level but at the level of system security in general. In particular neither system configuration files, nor files containing passwords or the backups of such files, nor "invisible" files (whose names start with a dot) — and this includes Vim swapfiles — should IMHO be visible to the lambda web user. Whether a privileged login should be allowed from a remote console is for every sysadmin to weigh seriously, with consideration of the particular system's requirements. On my machine I don't allow any remote login, and I don't open (other than in "view source" mode) emails from dubious sources, but of course other systems have other requirements: it is not always practical to require that privileged logins should be allowed only from one particular keyboard and screen located in the head office computer room, to which only a few select operators (or BOFHs) are allowed entry. Best regards, Tony. -- -- 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.
