Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 19 Oct 2017 12:44:28 -0700
From: Seth Arnold <>
Subject: Re: CVE-2017-8805: Unsafe symlinks not filtered in
 Debian mirror script ftpsync

On Wed, Oct 18, 2017 at 04:55:07PM -0400, Robert Watson wrote:
> Removing the ability for rsync to copy symlinks pointing to targets outside
> the mirror tree would greatly cripple it. I need to understand how the
> danger is worth the loss of this functionality.

Note that the fix isn't modifying rsync, the fix is modifying the ftpsync
script that calls rsync:

+    RSYNC_OPTIONS=${RSYNC_OPTIONS:-"-prltvHSB8192 --safe-links --timeout 3600 --stats --no-human-readable"}

Of course for people who run this mirroring tool as a specific user
account and set file permissions appropriately this is more or less a
no-op. But this is a useful hardening for people who run the ftpsync
command as a user with too many privileges. (I wouldn't have bothered
filing for a CVE for this change; I see it as a simple hardening change.)

This option shouldn't cripple ftpsync as a well-run repository is highly
unlikely to have symlinks pointing out of the tree. A repository with
symlinks pointing out of the tree is already not a suitable rsync source.


Download attachment "signature.asc" of type "application/pgp-signature" (474 bytes)

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.