public cloud security: surviving in a hostile multitenant environment

Public Cloud Security: Surviving in a Hostile Multitenant EnvironmentMark RussinovichTechnical Fellow, Azure

The Third Computing Era

Security Could Ruin Everything!

Source: 451 Research, Dec 2012

Identify threats Discuss riskExplore mitigations

Goals of this Session

Cloud Architecture

Cloud Operations

Hypervisor Hypervisor Hypervisor

Cloud Service APIs

DevOps

Deployer

DC Ops

Private Network

Attacker EnterpriseConsumerEnterprise

Priv

ate

Netw

ork

Internet

DatacenterCloud Service Provider

CSA periodically surveys industry experts to identify top cloud computing threatsFirst report published in 2010

Seven top threats

Most recent report published in February 2013

Nine top threatsSo close to a top ten list…

The Cloud Security Alliance “Notorious Nine”

https://cloudsecurityalliance.org/research/top-threats/

Some shared code defines the surface area exposed to customers:

CPU firmware/microcodeHypervisorWeb serverAPI support libraries…

10. Shared Technology Issues: Exposed Software

Cloud Service APIs

Datacenter

Hypervisor Hypervisor Hypervisor Hypervisor

What if there’s a vulnerability? 10. Shared Technology Issues

Stability and security are balanced against each otherAssumes infrastructure is accessible only by trusted actorsCorporate and legal mechanisms for dealing with attackers

10. Shared Technology Vulnerabilities: The Enterprise Approach

Enterprise Multi-tenancy

A vulnerability in publically accessible software enables an attacker to puncture the cloud

Breach exposes data of other customersSingle incident can cause catastrophic loss of customer confidenceCustomers (potential attackers) are anonymous and in diverse jurisdictions

10. Shared Technology Vulnerabilities: The Cloud Risk

Hypervisor Hypervisor Hypervisor

AttackerCustomer BCustomer A

10. Shared Technology Vulnerabilities: The Cloud Risk

http://www.zdnet.com/hypervisors-the-clouds-potential-security-achilles-heel-7000027846/

A vulnerability in publically accessible software enables an attacker to puncture the cloud

Breach exposes data of other customersSingle incident can cause catastrophic loss of customer confidenceCustomers (potential attackers) are anonymous and in diverse jurisdictions

New bug classification: “Cloud Critical”

10. Shared Technology Vulnerabilities: The Cloud Risk

Hostile Multi-tenancy

Enterprises and clouds are exposed to this riskClouds are at higher risk of exploitation:

Data from many customers makes it a rich targetAPI surface is trivial to access

Clouds are generally better at response:

Their business depends on itAutomated software deployment and patching required for cloud scaleBreach detection/mitigation necessary for preserving trust

10. Shared Technology Vulnerabilities: Bottom Line

My assessment

CSA assessment

Many companies are moving to the cloud and side-stepping IT processes:

Shadow IT: when business units bypass IT to deploy applications and store data in the cloudIT management, auditing, forensics, and access control systems are designed for on-premises servers and applications

Bottom line: IT must determine how to enable business units while enforcing corporate governanceIT must lead responsible adoption – it’s happening with or without them

9. Insufficient Due Diligence

“Bring Your Own IT” (BYOIT)

The agility and scale of the cloud is attractive to attackers, too

Use of compute as malware platform (Botmaster, DDOS platform)

8. Abuse of Cloud Services

The agility and scale of the cloud is attractive to attackers, too

Use of compute as malware platform (Botmaster, DDOS platform)Use of storage to store and distribute illegal contentUse of compute to mine digital currency

8. Abuse of Cloud Services

Hypervisor Hypervisor

Attacker

EnterpriseAttackerFriend

AWS

Attackers can use cloud resources and remain anonymous

Free trial offersStolen credit cardsHijacked accounts

Bottom line: reputation and COGS risk for cloud service providers

8. Abuse of Cloud Services: It’s Happening

For Cloud Service Providers Only

7. Malicious Insiders

Many cloud service provider employees have access to cloud:

Developers that write and devops cloud service codeOperators that deploy codeDatacenter operations personnel

7. Malicious Insiders

Cloud Operations

Hypervisor Hypervisor Hypervisor

Cloud Service APIs

DevOps

Deployer

DC Ops

Private Network

DatacenterCloud Service Provider

Mitigations:Employee background checksLimited as-needed access to productionControlled/monitored access to production services

Bottom line: real risk that is better understood via third-party audit/certification

7. Malicious Insiders

Employee background checksJust-in-time controls, auditingCertifications:

SO/IEC 27001:2005 SOC 1 and SOC 2 SSAE 16/ISAE 3402 AttestationsCloud Security Alliance Cloud Controls MatrixFederal Risk and Authorization Management Program (FedRAMP)Payment Card Industry (PCI) Data Security Standards (DSS) Level 1United Kingdom G-Cloud Impact Level 2 AccreditationHIPAA Business Associate Agreement (BAA)Family Educational Rights and Privacy Act (FERPA)

7. Malicious Insiders: Azure

The public cloud is…6. Denial of Service

well, public

The public cloud is…well, public

Service endpoints are subject to DDOS attacksCustomer applications are subject to targeted DDOS

Cloud outages are a form of DOS

6. Denial of Service

Hypervisor Hypervisor Hypervisor

Cloud Service APIs

AttackerEnterprise

Internet

Datacenter

DOS is a significant threatMitigations:

Cloud providers invest heavily in DDOS preventionNon-public applications can be isolated from the InternetGeo-available cloud providers can provide resiliency against many cloud outage vectors

Azure: DDOS prevention systemsGeo-regions for failover

6. Denial of Service: Bottom Line

Cloud is new and rapidly evolving, so lots of new API surfaceExamples:

Weak TLS cryptoIncomplete verification of encrypted content

5. Insecure Interfaces and APIs

Source: CSA - Cloud Computing Vulnerability Incidents: A Statistical Overview

Bottom line: Cloud providers must follow SDLCustomers should validate API behavior

5. Insecure Interfaces and APIs

Account hijacking: unauthorized access to an accountPossible vectors:

Weak passwordsStolen passwordsPassword reuse

4. Account or Service Traffic Hijacking

Account hijacking is not specific to the Cloud, but:

Cloud use may result in unmanaged credentialsPublically accessible applications/services may allow for brute forcingApplies to cloud provider: cloud support infrastructure is a back door

4. Account or Service Traffic Hijacking: Cloud Infrastructure Threats

Cloud OperationsHypervisor Hypervisor Hypervisor

Attacker

Cloud Service APIs

Mitigations:Turn off unneeded endpointsStrong passwordsMultifactor authenticationBreach detection

Azure: VM and Cloud Service Microsoft Antimalware IP ACLs (with static IP address)Point-to-Site, Site-to-Site, ExpressRouteAzure Active Directory MFA

4. Account or Service Traffic Hijacking: Bottom Line

There are multiple ways to lose cloud data:

Customer accidentally deletes or modifies itAttacker deletes or modifies itCloud provider accidentally deletes or modifies itNatural disaster destroys datacenter

3. Data Loss

Mitigations:Customer: point-in-time backups matter, even in the cloudCustomer: geo-redundant storageCloud Provider: deleted resource tombstoning

Azure: Globally Replicated StorageVM CaptureStorage snapshotsAzure Site Replica

3. Data Loss: Bottom Line

US North (primary)US South (secondary)

Really represents a collection of threats:

Insider threat, vulnerability in shared technology, etc.Ultimately, a company’s main asset is its dataHow does a company ensure its data is protected even in the face of successful breach?

Need to look at the threats individually…

2. Data Breaches

Threat: attacker gains access to media removed from datacenterMitigation: cloud provider physical controlsEnhanced mitigations:

Third-party certifications (e.g. FedRamp)Encryption at rest

Azure: third-party encryption

2. Data Breaches: Physical Attacks on Media

DC Ops

Threat: attacker man-in-the-middle snooping on data linksMitigations:

Cloud provider encrypts inter-DC trafficCloud provider APIs use TLSCustomer uses TLSCustomer encrypts outside of cloud

Azure: Brad Smith public promise

2. Data Breaches: Physical Attacks on Data Transfer

Cloud Service APIs

Attacker

Enterprise

Threat: Collocated attacker can infer secrets from processor side-effects

2. Data Breaches: Side-Channel Attacks

Threat: Collocated attacker can infer secrets from processor side-effects

2. Data Breaches: Side-Channel Attacks

Hypervisor

https://www.cs.unc.edu/~reiter/papers/2012/CCS.pdf

Researcher assumptions:Attacker knows precise cryptographic code customer is using and key strengthAttacker can collocate on same serverAttacker VM shares same physical core as customer VMCustomer VM continuously executes cryptographic codeOther customers performing similar algorithms do not share physical core

Bottom line: not currently a risk in practice

2. Data Breaches: Side-Channel Attacks

Threat: attacker gains logical access to dataMitigations:

Defense-in-depth preventionMonitoring/auditing

Encryption-at-rest: not a significant mitigation

Assume attacker can use keys

2. Data Breaches: Logical Attack on Storage

Cloud Service APIs

Attacker

Media breach is not a significant riskEncryption-at-rest doesn’t buy much

Network breach is a riskEncryption-on-the-wire is recommended

Logical breach is a riskEncryption-at-rest doesn’t buy much

2. Data Breaches: Bottom Line

1. Self-Awareness

Cloud Operations

Hypervisor Hypervisor Hypervisor

Cloud Service APIs

DevOps

Deployer

DC Ops

Private Network

Attacker EnterpriseConsumerEnterprise

Priv

ate

Netw

ork

Internet

DatacenterCloud Service Provider

http://cser.org

1. Self-awareness 2. Data breaches 3. Data loss 4. Account or service traffic hijacking 5. Insecure interfaces and APIs 6. Denial of service 7. Malicious insiders 8. Abuse of cloud services 9. Insufficient due diligence10. Shared technology vulnerabilities

The Top-10

As with any new technology, there are new risksIt’s our responsibility to educate our businesses and customers We can also develop tools and processes to mitigate risk

Summary