oss-security - Re: CVE Request -- vsftpd -- Do not create network namespace per connection

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Date: Mon, 06 Jun 2011 18:51:37 +0200
From: Jan Lieskovsky <jlieskov@...hat.com>
To: "Steven M. Christey" <coley@...us.mitre.org>
CC: oss-security@...ts.openwall.com, Chris Evans <scarybeasts@...il.com>,
        Greg KH <greg@...ah.com>, Kees Cook <kees@...ntu.com>
Subject: Re: CVE Request -- vsftpd -- Do not create network
 namespace per connection

On 06/06/2011 06:19 PM, Jan Lieskovsky wrote:
> Hello, Josh, Steve, vendors,
>
> It was found that vsftpd, Very Secure FTP daemon, when the network
> namespace (CONFIG_NET_NS) support was activated in the kernel, used to
> create a new network namespace per connection. A remote attacker could
> use this flaw to cause a memory pressure and denial of the vsftpd
> service.

Just to correct / tune up the impact a bit yet:
"A remote attacker could use this flaw to cause memory pressure (kernel
OOM killer protection mechanism to be activated and potentially
terminate vsftpd or arbitrary [vsftpd independent] process, which
satisfied the OOM killer process selection algorithm)."

Based on record of apache2 process termination in:
https://launchpadlibrarian.net/64456173/dmesg-oom.32.txt

Thanks to Petr Matousek for pointing this out.

Regards, Jan.
--
Jan iankko Lieskovsky / Red Hat Security Response Team

>
> References:
> [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373
> [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
> [3] https://bugzilla.redhat.com/show_bug.cgi?id=711134
>
> This one being a bit tricky one -- from my understanding of the issue,
> vsftpd doesn't necessarily have a security flaw on its side. It's
> kernel issue / bug, which allows this to be used for vsftpd DoS:
> [4] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/31
> [5] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/32
>
> Short-term solution would be probably to address this on the vsftpd
> side, the long-term one then being to get this fixed in kernel.
>
> Though not sure, how it would be wrt to CVE identifier(s) assignment.
>
> Steve, could you advice here?
>
> Thank you & Regards, Jan.
> --
> Jan iankko Lieskovsky / Red Hat Security Response Team

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