Are Today's FOSS Security Practices Robust Enough in the Cloud Era?

Lars Kurth Community Manger, Xen ProjectChairman, Xen Project Advisory BoardDirector, Open Source/Xen Project, Citrix

lars_kurth

About MeWas a contributor to various projectsWorked in parallel computing, tools, mobile and now virtualizationCommunity guy for the Xen ProjectWorking for CitrixMember of the group that develops XenServerChairman of Xen Project Advisory Board

Software bugs happenSome will be security

vulnerabilities

I

I: Vulnerability IntroducedD: Vulnerability Discovered

D

Discoverer exploits

issue for his own purpose

I

I: Vulnerability IntroducedD: Vulnerability Discovered

Discoverer reports security issues to security@yourproject

D

A team-effort to ensure that …•All (known) doors are closed•All (known) doors are locked•All (known) windows are

boarded up•Fences have no (known)

weaknesses•…

Vulnerability ManagementProcess =

XF

Pattern: Full Disclosure

R: Vulnerability ReportedT: TriageA: Vulnerability AnnouncedF: Fix Available X: Fix Deployed

Vulnerability is known by the reporter and the security teamNote: It may also be known and used by black hats Vulnerability is known publicly with no fix availableVulnerability is known publicly with fix available

BasicDescription

R T A

Patch/fix creation and validation

Pattern: Responsible Disclosure

X

R: Vulnerability ReportedT: TriageP: Vulnerability Pre-disclosedA: Vulnerability AnnouncedF: Fix Available X: Fix Deployed

Vulnerability is known by the reporter and the security teamNote: It may also be known and used by black hats Vulnerability is known about by a privileged and small group of users Vulnerability is known publicly

APre-disclosure period

R PPatch/fix creation and validation

FT

Purpose of Vulnerability Process = Keeping Your Users Safe

What does safety mean?

Encourage discoverers to report security issues to security@yourprojectDiscoverers are in control You can’t stop them from releasing/using informationA robust vulnerability process encourages discoverers to work with you

What does safety mean?

Ensure that your project fixes security issues as quickly as possibleYou don’t want unaddressed vulnerabilities

What does safety mean?

Exposure time to security issues is minimized A maximum of users* apply patches quickly Minimize risk

Linux Kernel/LXC/KVM if reported via OSS SecurityLinux Kernel/LXC/KVM if reported via security@kernel.orgOpenStack, QEMU, … for low impact issues

Full

Linux Kernel/LXC/KVM if reported via OSS Security DistrosLinux Distributions (both open source and commercial)QEMU, Libvirt, oVirt, ...OpenStack for intermediate to high impact issuesOPNFV, OpenDayLight : process modeled on OpenStackXen Project for all issues (also handles 3rd party issues, e.g. QEMU)Docker : states responsible disclosure; but policy docs empty / some CVEs

Responsible

Cloud Foundry : no clearly stated process; no published CVE’sCoreOS: just a mail to report issuesKubernetes: : just a mail to report issues (when I wrote this talk in Aug, no info)

Not clearly stated

Approaches used by Cloud ProjectsApproach Used by Projects

Example: OpenDayLight & Netdump

Open-source software projects are often well intended, but security can take a back seat to making the code work. OpenDaylight, the multivendor software-defined networking (SDN) project, learned that the hard way last August after a critical vulnerability was found in its platform. It took until December for the flaw, called Netdump, to get patched …

PC World, March 2015

Anatomy of ResponsibleDisclosure In DetailUsing the pre-dominant model as baselineApplies to Linux Distros, OSS Sec Distros, QEMU, …

Mike Licht @ Flickr

Responsible Disclosure In Detail

A X

Typically fixed time during which the security issue is handled secretly Depends on discoverer’s wishes

R: Vulnerability ReportedT: TriageP: Vulnerability Pre-disclosedA: Vulnerability AnnouncedF: Fix Available X: Fix Deployed

Vulnerability is known by the reporter and the security teamNote: It may also be known and used by black hats Vulnerability is known about by a privileged and small group of users Vulnerability is known publicly

Description, CVEallocation, …

Pre-disclosure period

RPatch/fix creation and validation

FT P

What can and can’t be done with privileged information can differ significantly between projects

Small differences, canhave large consequences

mindfulness @ Flickr

Example: Disclosure Time

F A XR

Disclosure Time

Long disclosure times discredit responsible disclosureFrom a few days to many months

Long disclosure times create a disincentive for reporters to work with youIncreases the risk of 0 day exploits

Pre-defined disclosure times help manage vendorsExample later

Most successful projects have a 2-3 weeks disclosure period

Example:To CVE or not to CVE?Assigning CVE numbers is best practice in by established projects and vendors in the Linux/Cloud ecosystem

CVE databases (such as www.cvedetails.com) can be used to evaluate your project

This shows Xen Project CVE statsBefore 2012, we didn’t have fewer vulnerabilities than afterWe just didn’t have a process requiring creation of CVEs

A fair comparison between projects/technologies using CVE data is not easily possibleNot all projects/products create CVEs for all their issues Example: Linux/QEMU only do so for severe onesPolicies are not always published

Some projects don’t assign CVEs at allSome technologies/products cannot be easily identified in databases Example: KVM, LXC

Sometimes CVEs can affect several productsBut are counted only against oneOpen source product definitions on cvedetails are often sloppy

How do Projects that use Responsible Disclosure differ?

Mike Licht @ Flickr

Description, CVEallocation, …

Revisit: Responsible Disclosure

A DPre-disclosure period

RPatch/fix creation and validation

FT P

What happens here dependson your process goals

Common Process GoalsMake sure that a fix is available before disclosureMake sure that downstream projects and products (e.g. distros) can package and test the fix in their environment

Allow service providers that use your Software to start planning an upgrade (at scale this can take a week)Allow service providers that use your Software to deploy an upgrade before the embargo completes

Your Process Goals Determine …What is allowed during pre-disclosureWho is privileged and trusted to be on the pre-disclosure mailing list

Disclosure Time

Make sure that a fix is available before disclosureMake sure that downstream projects and products (e.g. distros) can package and test the fix in their environment

Allow service providers that use your Software to start planning an upgrade (at scale this can take a week)Allow service providers that use your Software to deploy an upgrade before the embargo completesCloud Model

Distro Model

Emerged recently! Recognizes the needs of service providers

Pre-Cloud Computing! Services and their users are vulnerableimmediately after disclosure

Responsible Disclosure by ProjectsApproach Used by Projects

Linux Kernel/LXC/KVM if reported via OSS Security DistrosLinux Distributions (both open source and commercial)QEMU, Libvirt, oVirt, ...

OpenStack for intermediate to high impact issuesOPNFV, OpenDayLight : process modeled on OpenStackXen Project for all issues (also handles 3rd party issues, e.g. QEMU)Docker: depends on severity, details only available on request

Trade-Offs:Distro vs. Cloud Model

Risk for usersMore Cloud/Service users than direct users of your softwareExample: AWS stated in 2014 that they have > 1M users (and a lot more instances)AliCloud claims that they have > 1M users…

Risk to your Project’s Reputation

Just imagine what the reputation damage would have been, if Xen had put AWS, Rackspace, SoftLayer, … users at real risk of a vulnerability.

There were 100’s ofstories at the time,despite the fact thatusers were never putat risk, but merely inconvenienced !

Risk of Information LeakagePre-disclosure list membership: more members, more risk of leakageIn the Distro Model, the number of privileged users is typically <10In the Cloud Model, the number could be an order of magnitude higher (50-100)This increases risk of information being accidentally released

FairnessRestricting pre-disclosure list membershipRestricting membership to large service providers to minimize riskThat creates issues of “fairness” Which may be incompatible with your communities' values

War Stories:How the Xen Project got to its Vulnerability Processxenproject.org/security-policy.html

Moyan Brenn @ Flickr

2011 2012 2013 2014 2015 2016

V1.0 : Modelled on DebianGoals: Allow fixing, packaging and testing; Allow service providers to prepare (but not deploy) during embargoPre-disclosure: Membership biased towards distros & large service providersNo predefined disclosure time

1.0

2011 2012 2013 2014 2015 2016

July 2012: CVE-2012-0217, Intel SYSRETAffected FreeBSD, NetBSD, Solaris, Xen and Microsoft Windows

A large pre-disclosure list member put pressure on key members of the Xen Project Community to get an embargo extension They eventually convinced the discoverer to request an extension

1.0

2011 2012 2013 2014 2015 2016

Community Consultation to improve our processCentered on: Predetermined disclosure schedule: 1 week to fix, 2 weeks embargoWho should be allowed on the pre-disclosure listFairness issues between small and large service providersDirect vs. indirect Xen consumersThe risk of larger pre-disclosure list membership

1.0

2011 2012 2013 2014 2015 2016

V2.0 : Clarifications Strongly recommended disclosure scheduleInclusive pre-disclosure list membership Changes to application procedure (based on checkable criteria)

1.0 2.0

2011 2012 2013 2014 2015 2016

Sept 2014: CVE-2014-7118 Leading to the first Cloud Reboot

AWS pre-announced cloud reboot to their customersOther vendors didn’t. Policy was interpreted differently by vendors.This highlighted ambiguities in the project’s security policy(what can/can’t be said/done during an embargo)

1.0 2.0

2011 2012 2013 2014 2015 2016

V3.0 : Deploy & OptimizationsGoals: Allow fixing, packaging and testingAllow service providers to prepare (and normally to deploy) during embargo

Pre-disclosure: Clearer application criteriaPublic application process (transparency) Clear information on what is/is not allowed during an embargo (per XSA)Means for pre-disclosure list members to collaborate

1.0 2.0 3.0

2011 2012 2013 2014 2015 2016

Conducted XSA-133 Retrospective upon requestProcess change: Earlier embargoed pre-disclosure without patches

May 2015: CVE-2015-3456First time we were affected by a branded bug

QEMU bug, which was handled by several security teams: QEMU,OSS Distro Security, Oracle Security & Xen ProjectFrom a process perspective: were not able to provide a fix 2 weeks before the embargo date ended

1.0 2.0 3.0

Lessons LearnedLarger pre-disclosure list has not caused a single issues in two years of operating an inclusive approachWe have not had a single 0-day vulnerability

A well run vulnerability process builds trustWillingness to adapt to your stake-holders needs builds more trustIt creates collaboration and understanding of stake-holders

Fairness is a difficult issue

There will always be practical issues, e.g. “interpretations of policy”, etc.

On FairnessThe Xen Project’s process is the only example case, where this issue has been tackled through a community consultation.

To Contrast:OpenStack does not publish who is on their pre-disclosure listOpenStack does not have a formal application processAvoids dealing with the “fairness” issue head-on

Trade-off: On Media Hype and Security Practices

Why was Xen singled out?Security stories are “hot”Xen is widely used, thus security stories “sell”It’s too easy for reporters to write a story

Reporters just have to check our page,and know when the next story comes

Are Security Practices Robust Enoughin the CloudEra?

Source: yanilavigne.net viadomics.me

Very wide range of approaches vs.The reality that SW stacks contain many layers Consider the weakest link in your SW stack

Best Practice appears to be emergingOlder projects seem slow to changeNew projects, don’t build security management into their culture from the beginning

New Post-Snowden era pressuresHow to effectively deal with media Hype?