Remotely exploitable heap overflow in rsync
| From: | rsync-announce-AT-lists.samba.org | |
| To: | rsync-announce-AT-lists.samba.org, rsync-AT-lists.samba.org | |
| Subject: | [rsync-announce] rsync security advisory | |
| Date: | Thu, 4 Dec 2003 16:55:27 +1100 |
rsync 2.5.6 security advisory
-----------------------------
December 4th 2003
Background
----------
The rsync team has received evidence that a vulnerability in rsync was
recently used in combination with a Linux kernel vulnerability to
compromise the security of a public rsync server. While the forensic
evidence we have is incomplete, we have pieced together the most
likely way that this attack was conducted and we are releasing this
advisory as a result of our investigations to date.
Our conclusions are that:
- rsync version 2.5.6 contains a heap overflow vulnerability that can
be used to remotely run arbitrary code.
- While this heap overflow vulnerability could not be used by itself
to obtain root access on a rsync server, it could be used in
combination with the recently announced brk vulnerability in the
Linux kernel to produce a full remote compromise.
- The server that was compromised was using a non-default rsyncd.conf
option "use chroot = no". The use of this option made the attack on
the compromised server considerably easier. A successful attack is
almost certainly still possible without this option, but it would
be much more difficult.
Please note that this vulnerability only affects the use of rsync as a
"rsync server". To see if you are running a rsync server you should
use the netstat command to see if you are listening on TCP port
873. If you are not listening on TCP port 873 then you are not running
a rsync server.
New rsync release
-----------------
In response we have released a new version of rsync, version
2.5.7. This is based on the current stable 2.5.6 release with only the
changes necessary to prevent this heap overflow vulnerability. There
are no new features in this release.
We recommend that anyone running a rsync server take the following
steps:
1) update to rsync version 2.5.7 immediately
2) if you are running a Linux kernel prior to version 2.4.23 then
you should upgrade your kernel immediately. Note that some
distribution vendors may have patched versions of the 2.4.x
series kernel that fix the brk vulnerability in versions before
2.4.23. Check with your vendor security site to ensure that you
are not vulnerable to the brk problem.
3) review your /etc/rsyncd.conf configuration file. If you are
using the option "use chroot = no" then remove that line or
change it to "use chroot = yes". If you find that you need that
option for your rsync service then you should disable your rsync
service until you have discussed a workaround with the rsync
maintainers on the rsync mailing list. The disabling of the
chroot option should not be needed for any normal rsync server.
The patches and full source for rsync version 2.5.7 are available from
http://rsync.samba.org/ and mirror sites. We expect that vendors will
produce updated packages for their distributions shortly.
Credits
-------
The rsync team would like to thank the following individuals for their
assistance in investigating this vulnerability and producing this
response:
* Timo Sirainen <tss iki.fi>
* Mike Warfield <mhw wittsend.com>
* Paul Russell <rusty samba.org>
* Andrea Barisani <lcars gentoo.org>
Regards,
The rsync team
_______________________________________________
rsync-announce mailing list
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Posted Dec 4, 2003 18:44 UTC (Thu)
by utoddl (guest, #1232)
[Link] (4 responses)
Posted Dec 4, 2003 19:14 UTC (Thu)
by hamjudo (guest, #363)
[Link] (3 responses)
It now says
Posted Dec 4, 2003 20:13 UTC (Thu)
by Ross (guest, #4065)
[Link] (2 responses)
Posted Dec 4, 2003 19:31 UTC (Thu)
by smoogen (subscriber, #97)
[Link]
-- Or have been rooted already and netstat has been replaced.
Posted Dec 4, 2003 20:45 UTC (Thu)
by stevenj (guest, #421)
[Link] (2 responses)
Those guys are fast.
Posted Dec 5, 2003 3:26 UTC (Fri)
by proski (subscriber, #104)
[Link] (1 responses)
Posted Dec 5, 2003 5:24 UTC (Fri)
by proski (subscriber, #104)
[Link]
Posted Dec 4, 2003 23:33 UTC (Thu)
by JoeBuck (subscriber, #2330)
[Link] (1 responses)
Any connection to the Gentoo attack?
Posted Dec 4, 2003 23:34 UTC (Thu)
by JoeBuck (subscriber, #2330)
[Link]
Ignore previous comment; I went directly to the story from Slashdot so I didn't see the teaser item on the main LWN page.
What about versions prior to 2.5.6? The article isn't clear on that.
Remotely exploitable heap overflow in rsync
All the previous versions that support the remote protocol, rsync server, are vulnerable.
See
rsync.samba.org
for a revised announcement.Remotely exploitable heap overflow in rsync
- rsync version 2.5.6 and earlier contains a heap overflow...
But it should say "contains" :)
Remotely exploitable heap overflow in rsync
Please note that this vulnerability only affects the use of rsync as aRemotely exploitable heap overflow in rsync
"rsync server". To see if you are running a rsync server you should
use the netstat command to see if you are listening on TCP port
873. If you are not listening on TCP port 873 then you are not running
a rsync server.
I just checked, and an rsync_2.5.5-0.2 package has apparently just been uploaded to the Debian security server; the changelog indicates that it is for the bug reported here.new Debian package is uploaded
Debian unstable still has no updates. In addition to that, there is a dependency problem that prevents upgrading Python. Such problems are normally resolved next day, but now we are stuck in this state for more than a week.
new Debian package is uploaded
There are new updates in unstable. Python is fixed. It happened just an hour after my previous post. Quite a coincidence.
new Debian package is uploaded
Remotely exploitable heap overflow in rsync
Duh