oss-sec mailing list archives
Re: CVE Request -- vsftpd -- Do not create network namespace per connection
From: Chris Evans <scarybeasts () gmail com>
Date: Mon, 6 Jun 2011 10:14:13 -0700
On Mon, Jun 6, 2011 at 9:19 AM, Jan Lieskovsky <jlieskov () redhat 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: [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:
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 :) [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.
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
Current thread:
- CVE Request -- vsftpd -- Do not create network namespace per connection Jan Lieskovsky (Jun 06)
- Re: CVE Request -- vsftpd -- Do not create network namespace per connection Greg KH (Jun 06)
- Re: CVE Request -- vsftpd -- Do not create network namespace per connection Chris Evans (Jun 06)
- Re: CVE Request -- vsftpd -- Do not create network namespace per connection Jan Lieskovsky (Jun 06)
- Re: CVE Request -- vsftpd -- Do not create network namespace per connection Josh Bressers (Jun 06)
- Re: CVE Request -- vsftpd -- Do not create network namespace per connection Eugene Teo (Jun 06)