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Five new undisclosed Xen vulnerabilities

xenbits.xen.org

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Re: Five new undisclosed Xen vulnerabilities

#21
post #12

Earlier quoted context omitted.

Good thing the host you run Docker on never needs to be patched or rebooted I guess?

Yes, docker is immune to vulnerabilities because containers.

If the kernel you are running on is vulnerable, it can be attacked and the attacker can circumvent any container isolation.

If the hypervisor (Xen!) running underneath your container-Linux is vulnerable, the attacker can get access to your virtualized OS and circumvent any container isolation.

Re: Five new undisclosed Xen vulnerabilities

#22

Xen's hypervisor would seem to be a great place to implement live patching like KSplice/kGraft/Kpatch does for the Linux kernel. Presumably that stuff still works on KVM host machines with live guests.

There was this talk at last Linux Plumbers Conference, fyi: http://www.linuxplumbersconf.org/2014/ocw/sessions/2421

Re: Five new undisclosed Xen vulnerabilities

#24
post #15
post #2

Just received a message from Rackspace cloud regarding theses, it seems like they will have to reboot all instances. See https://community.rackspace.com/general/f/53/t/4978

Yet linode is still silent...

realize that there's Xen HVM and Xen PV. there have been significantly more security issues in HVM than there have been in PV.

Re: Five new undisclosed Xen vulnerabilities

#25
AWS have posted an update about related upcoming EC2 maintenance: https://aws.amazon.com/premiumsupport/maintenance-2015-03/

"We’ve received a Xen Security Advisory that requires us to update a portion of our Amazon EC2 fleet. Fewer than 10% of EC2 customer instances will need to be rebooted. We’ve started notifying affected customers when their reboots will take place. These updates must be completed by March 10, 2015 before the underlying issues we are addressing are made public. Following security best practices, the details behind these issues will be withheld until they are made public on March 10."

Re: Five new undisclosed Xen vulnerabilities

#26

Earlier quoted context omitted.

See ya later uptime... 04:49:58 up 659 days your server is vulnerable to a number of Xen security vulnerabilities: http://xenbits.xen.org/xsa/ Including this one from Oct 1, 2014 that allows guests to read up to 3KB of memory from the hypervisor or other guests: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7188 http://threatpost.com/serious-hypervisor-bug-fix-causes-unex...

That vulnerability only applies to HVM guests. No doubt there are other reasons to have rebooted since 2013, but if one of Rackspace's servers only has paravirtualized guests (do they use HVM at all? I don't know), they can get by without patching it.

rackspace most likely uses hvm guests. I think they had freebsd before there was xen pv support

Re: Five new undisclosed Xen vulnerabilities

#27
post #12

Earlier quoted context omitted.

Yes, docker is immune to vulnerabilities because containers.

If the kernel you are running on is vulnerable, it can be attacked and the attacker can circumvent any container isolation. If the hypervisor (Xen!) running underneath your container-Linux is vulnerable, the attacker can get access to your virtualized OS and circumvent any container isolation.

your sarcasm detector may need recalibration.

Re: Five new undisclosed Xen vulnerabilities

#28
post #24
post #15

Earlier quoted context omitted.

Yet linode is still silent...

realize that there's Xen HVM and Xen PV. there have been significantly more security issues in HVM than there have been in PV.

Do we know why HVM/hw-virt has had more security issues than PV/sw-virt?

Re: Five new undisclosed Xen vulnerabilities

#29
post #15
post #2

Just received a message from Rackspace cloud regarding theses, it seems like they will have to reboot all instances. See https://community.rackspace.com/general/f/53/t/4978

Yet linode is still silent...

I got an email from linode yesterday telling me they need to do the same. Not sure if they had any public communication yet.

Re: Five new undisclosed Xen vulnerabilities

#30
post #2

Just received a message from Rackspace cloud regarding theses, it seems like they will have to reboot all instances. See https://community.rackspace.com/general/f/53/t/4978

See ya later uptime... 04:49:58 up 659 days

Is that a guest or a host? If it's a guest, there shouldn't be a need for reboot, only suspend/resume... (note that a reboot can be a good idea from time to time, just to make sure the current configuration (eg: post kernel upgrades, before reboot) -- actually boots).
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