Date: Mon, 6 Jun 2011 10:14:13 -0700 From: Chris Evans <scarybeasts@...il.com> To: oss-security <oss-security@...ts.openwall.com> Cc: "Steven M. Christey" <coley@...us.mitre.org>, Greg KH <greg@...ah.com>, Kees Cook <kees@...ntu.com> Subject: Re: CVE Request -- vsftpd -- Do not create network namespace per connection On Mon, Jun 6, 2011 at 9:19 AM, Jan Lieskovsky <jlieskov@...hat.com> 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. > > References: >  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373 >  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095 >  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: > Yes, I will be considering this a kernel issue. vsftpd also uses one (or more!) process per connection. I'd have though that a process structure plus stack etc. would be a lot more heavyweight than an empty network namespace, but obviously not :)  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/31 >  > 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. > It's actually configurable in vsftpd.conf: isolate_network=NO So for a short term fix, all you need is to deploy that config change. Looking at the Changelog, network isolation was added in vsftpd-2.2.0, and the config setting has been there from v2.2.0 as well. Cheers Chris > 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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