Date: Tue, 07 Jun 2011 07:19:14 +0800 From: Eugene Teo <eugene@...hat.com> To: oss-security@...ts.openwall.com CC: Jan Lieskovsky <jlieskov@...hat.com>, "Steven M. Christey" <coley@...us.mitre.org>, 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 06/07/2011 12:19 AM, 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. > > 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: >  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. > > Though not sure, how it would be wrt to CVE identifier(s) assignment. > > Steve, could you advice here? It is worth noting that for a local, unprivileged user to trigger this, they will need to have the CAP_SYS_ADMIN capability. So this limits the attack to some services like vsftpd. I see this more of a kernel issue as configuring vsftpd to set isolate_network=NO is not a long-term solution. Thanks, Eugene
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