Public Key Infrastructure Public Key Infrastructure – – Deep Dive PKI session SHOWING Deep Dive PKI session SHOWING you how to embrace PKI you how to embrace PKI

Steve LambSteve Lamb

stephlam@microsoft.comstephlam@microsoft.com

http://blogs.technet.com/steve_lambhttp://blogs.technet.com/steve_lamb

IT Pro Security EvangelistIT Pro Security Evangelist

Microsoft LtdMicrosoft Ltd

AgendaAgenda

What can PKI enableWhat can PKI enable

Let’s review the theoryLet’s review the theory

Introducing our Demonstration EnvironmentIntroducing our Demonstration Environment

Secure Web PublishingSecure Web Publishing

Secure EmailSecure Email

Secure FilesSecure Files

RecommendationsRecommendations

What can PKI enable?What can PKI enable?

Secure Email – sign and/or encrypt messages

Secure browsing – SSL – authentication and encryption

Secure code – authenticode

Secure wireless – PEAP & EAP-TLS

Secure documents – Rights Management

Secure networks – segmentation via IPsec

Secure files – Encrypted File System(EFS)

Let’s review the theory…Let’s review the theory…

SecuritySecurityDefense in DepthDefense in Depth

Data and Resources

Application Defenses

Host Defenses

Network Defenses

Perimeter Defenses

Symmetric Key CryptographySymmetric Key Cryptography

EncryptionEncryption

““The quick The quick brown fox brown fox jumps over jumps over the lazy the lazy dog”dog”

““AxCv;5bmEseTfid3)AxCv;5bmEseTfid3)fGsmWe#4^,sdgfMwifGsmWe#4^,sdgfMwir3:dkJeTsY8R\s@!r3:dkJeTsY8R\s@!q3%”q3%”

““The quick The quick brown fox brown fox jumps over jumps over the lazy the lazy dog”dog”

DecryptionDecryption

Plain-text inputPlain-text input Plain-text outputPlain-text outputCipher-textCipher-text

Same keySame key(shared secret)(shared secret)

Public Key EncryptionPublic Key Encryption

EncryptionEncryption

““The quick The quick brown fox brown fox jumps over jumps over the lazy the lazy dog”dog”

““Py75c%bn&*)9|Py75c%bn&*)9|fDe^bDFaq#xzjFr@gfDe^bDFaq#xzjFr@g5=&nmdFg$5knvMd’r5=&nmdFg$5knvMd’rkvegMs”kvegMs”

““The quick The quick brown fox brown fox jumps over jumps over the lazy the lazy dog”dog”

DecryptionDecryption

Clear-text InputClear-text Input Clear-text OutputClear-text OutputCipher-textCipher-text

DifferentDifferent keys keys

Recipient’s Recipient’s public keypublic key

Recipient’s Recipient’s private keyprivate key

privatprivatee

publicpublic

Hybrid Encryption (Real World)Hybrid Encryption (Real World)

As above, repeated As above, repeated for other recipientsfor other recipientsor recovery agentsor recovery agents

DigitalDigitalEnvelopeEnvelope

Other recipient’s or Other recipient’s or agent’s agent’s publicpublic key key (in certificate)(in certificate)in recovery policyin recovery policy

Launch keyLaunch keyfor nuclearfor nuclear

missile missile ““RedHeat” RedHeat”

is...is...

Symmetric key Symmetric key encrypted asymmetrically encrypted asymmetrically

(e.g., RSA)(e.g., RSA)

Digital Digital EnvelopeEnvelope

User’sUser’spublicpublic key key(in certificate)(in certificate)

RNGRNG

Randomly-Randomly-Generated Generated symmetricsymmetric“session” key “session” key

SymmetricSymmetric encryption encryption(e.g. DES)(e.g. DES)

*#$fjda^j*#$fjda^ju539!3tu539!3t

t389E *&\@t389E *&\@5e%32\^kd5e%32\^kd

Introducing our Introducing our demonstration environmentdemonstration environment

Network InfrastructureNetwork Infrastructure

Certification AuthorityCertification Authority

Installed on the DC for simplicityInstalled on the DC for simplicity

In production use a multi-level hierarchyIn production use a multi-level hierarchy

Enterprise Installation – integrated with ADEnterprise Installation – integrated with AD

Secure Web PublishingSecure Web Publishing

Application Layer Application Layer ContentContent

????????????????????????????????????????????

A Traditional Firewall’s ViewA Traditional Firewall’s Viewof a Packetof a Packet

Only packet headers are inspectedOnly packet headers are inspected

Application layer content appears as “black box”Application layer content appears as “black box”IP HeaderIP Header

Source Address,Dest. Address,

TTL, Checksum

TCP TCP HeaderHeaderSequence Number

Source Port,Destination Port,

Checksum

Forwarding decisions based on port numbersForwarding decisions based on port numbers

Legitimate traffic and application layer attacks use identical portsLegitimate traffic and application layer attacks use identical ports

Internet Expected HTTP Traffic

Unexpected HTTP Traffic

Attacks

Non-HTTP Traffic

Corporate Network

ISA Server’s View of a PacketISA Server’s View of a Packet

Application Layer Application Layer ContentContent

<html><head><meta http- quiv="content-type" content="text/html;

charset=UTF-8"><title>MSNBC - MSNBC

Front Page</title><link rel="stylesheet"

IP HeaderIP HeaderSource Address,Dest. Address,

TTL, Checksum

TCP TCP HeaderHeaderSequence Number

Source Port,Destination Port,

Checksum

Forwarding decisions based on contentForwarding decisions based on content

Only legitimate and allowed traffic is processedOnly legitimate and allowed traffic is processed

Internet Expected HTTP Traffic

Unexpected HTTP Traffic

Attacks

Non-HTTP Traffic

Corporate Network

Packet headers and application content are inspectedPacket headers and application content are inspected

Configure IIS for HTTPSConfigure IIS for HTTPS

Populate sitePopulate site

Enrol for web server certificateEnrol for web server certificate

Configure SSLConfigure SSL

Configure ISA for SSLConfigure ISA for SSL

Copy web server cert to ISACopy web server cert to ISA

Publish the web serverPublish the web server

Use the Wizard!Use the Wizard!

Create an SSL listenerCreate an SSL listener

Secure EmailSecure Email

How Exchange RPC WorksHow Exchange RPC Works

ServiceService UUIDUUID PortPort

ExchangeExchangeInfo StoreInfo Store

{0E4A0156-DD5D-11D2-8C2F-{0E4A0156-DD5D-11D2-8C2F-00CD4FB6BCDE}00CD4FB6BCDE}

44024402

Active Active DirectoryDirectory

{E35114235-4B06-11D1-AB04-{E35114235-4B06-11D1-AB04-00C04C2DCD2}00C04C2DCD2}

35443544

Performance Performance MonitorMonitor

{A00C021C-2BE2-11D2-B678-{A00C021C-2BE2-11D2-B678-0000F87A8F8E}0000F87A8F8E}

92339233

RPC Server (Exchange)

RPC Client (Outlook)

TCP 135:

Port for {

0E4A…}Port 4402:

Data

The RPC server maintains a table of Universally Unique Identifiers (UUID) and assigned port

1

The client connects to TCP port 135 on the server to query for the port associated with a UUID

2

The server responds with theassociated port

3

The client reconnects to server on the designated port to access Exchange Server

4

Server: Port

4402

Internet

RPC and Traditional FirewallsRPC and Traditional Firewalls

Open port 135 for Open port 135 for incoming trafficincoming traffic

Open every port that Open every port that RPC RPC mightmight use for use for incoming trafficincoming traffic

RPC Server (Exchange)

RPC Client (Outlook)

TCP 135:

Port fo

r {0E4A…

?

Port 4402:

Data

Server:

Port

4402

Traditional firewalls can’t Traditional firewalls can’t provide provide securesecure RPC access RPC accessTraditional firewalls can’t Traditional firewalls can’t provide provide securesecure RPC access RPC access

Internet

RPC and ISA ServerRPC and ISA ServerRPC Server (Exchange)

RPC Client (Outlook)

TCP 135:

Port fo

r {0E4A…

?

Port 4402:

Data

Server:

Port

4402

Internet

Initial connectionInitial connection

Only allows valid RPC trafficOnly allows valid RPC traffic

Blocks non-Exchange queriesBlocks non-Exchange queries

Secondary connectionSecondary connection

Only allows connectionOnly allows connectionto port used byto port used byExchangeExchange

EnforcesEnforcesencryptionencryption

ISA Server enables secure ISA Server enables secure remote e-mail access using remote e-mail access using

OutlookOutlook

ISA Server enables secure ISA Server enables secure remote e-mail access using remote e-mail access using

OutlookOutlook

Configure Secure EmailConfigure Secure Email

Request a “user” certRequest a “user” cert

Configure Outlook to use the certConfigure Outlook to use the cert

Send Signed / Encrypted messageSend Signed / Encrypted message

Secure FilesSecure Files

Protecting files (“Stop thief!”)Protecting files (“Stop thief!”)

BIOS passwordsBIOS passwordsNot universally supportedNot universally supportedPretty much no recovery if you forget!Pretty much no recovery if you forget!

Good passwordsGood passwordsMitigate “pass-the-hash” attacksMitigate “pass-the-hash” attacks

SysKey mode 3SysKey mode 3Useful mostly for protecting local accountsUseful mostly for protecting local accountsUse system restore disk if you forgetUse system restore disk if you forget

Encrypting file system (EFS)Encrypting file system (EFS)Transparent to applications and usersTransparent to applications and usersComputationally infeasible to break (domain accts or SysKey 3)Computationally infeasible to break (domain accts or SysKey 3)MustMust implement recovery agents; better with domain and PKI implement recovery agents; better with domain and PKI

EFS operationEFS operation

Assumptions: domain accounts, enterprise CA, Windows Server 2003, Windows XP

EFS certificate requestEFS certificate requestwith public EFS keywith public EFS key

generate generate public and public and

private private EFS keysEFS keys

public key bound to public key bound to cert; store cert and cert; store cert and private key in profileprivate key in profile

generate file generate file encryption keyencryption key

encrypt FEK encrypt FEK with EFS with EFS

keykey

encrypt FEK encrypt FEK with default with default

recovery agentrecovery agent

Avoid EFS “gotchas”Avoid EFS “gotchas”Back up that EFS certificate and the keys!Back up that EFS certificate and the keys!

You will lose accessYou will lose access if you have no PKI or DRA if you have no PKI or DRA

CIPHER /XCIPHER /X command command store on USB drive store on USB drive

Also export local DRA and remove from computerAlso export local DRA and remove from computer

Eliminate plain-text “shreds”Eliminate plain-text “shreds”

Encrypt folders, not filesEncrypt folders, not files

CIPHER /WCIPHER /W wipe slack space: 00-FF-random wipe slack space: 00-FF-random

Please, just use an enterprise CAPlease, just use an enterprise CA

Set up for auto-enrollmentSet up for auto-enrollment

Configure DRA in group policyConfigure DRA in group policy

Now you won’t have any worriesNow you won’t have any worries

RecommendationsRecommendationsDon’t be scared of PKI!Don’t be scared of PKI!

Set up a test environment to enable you to “play”Set up a test environment to enable you to “play”

Minimise the scope of your first implementationMinimise the scope of your first implementation

Read up on CP & CPSRead up on CP & CPS

Document the purpose and operating Document the purpose and operating procedures of your PKIprocedures of your PKI

SummarySummary

Cryptography is a rich and amazingly mature Cryptography is a rich and amazingly mature fieldfield

We all rely on it, everyday, with our livesWe all rely on it, everyday, with our lives

Know the basics and make good choices Know the basics and make good choices avoiding common pitfallsavoiding common pitfalls

Plan your PKI earlyPlan your PKI early

Avoid very new and unknown solutionsAvoid very new and unknown solutions

ReferencesReferences

Visit www.microsoft.com/security Visit www.microsoft.com/security

Read sci.crypt (incl. archives)Read sci.crypt (incl. archives)

For more detail, read:For more detail, read:Cryptography: An Introduction, Cryptography: An Introduction, N. Smart, McGraw-Hill, ISBN 0-07-709987-7N. Smart, McGraw-Hill, ISBN 0-07-709987-7

Practical Cryptography, Practical Cryptography, N. Ferguson & B. Schneier, Wiley, ISBN 0-471-22357-3N. Ferguson & B. Schneier, Wiley, ISBN 0-471-22357-3

Contemporary Cryptography, Contemporary Cryptography, R. Oppliger, Artech House, ISBN 1-58053-642-5 (to R. Oppliger, Artech House, ISBN 1-58053-642-5 (to be published May 2005, see http://www.esecurity.ch/Books/cryptography.html)be published May 2005, see http://www.esecurity.ch/Books/cryptography.html)

Applied CryptographyApplied Cryptography, B. Schneier, John Wiley & Sons, ISBN 0-471-11709-9, B. Schneier, John Wiley & Sons, ISBN 0-471-11709-9

Handbook of Applied CryptographyHandbook of Applied Cryptography, A.J. Menezes, CRC Press, ISBN 0-8493-, A.J. Menezes, CRC Press, ISBN 0-8493-8523-7, 8523-7, www.cacr.math.uwaterloo.ca/hacwww.cacr.math.uwaterloo.ca/hac (free PDF) (free PDF)PKI, PKI, A. Nash et al., RSA Press, ISBN 0-07-213123-3A. Nash et al., RSA Press, ISBN 0-07-213123-3

Foundations of CryptographyFoundations of Cryptography, O. Goldereich, , O. Goldereich, www.eccc.uni-trier.de/eccc-local/ECCC-Books/oded_book_readme.htmlwww.eccc.uni-trier.de/eccc-local/ECCC-Books/oded_book_readme.html

Cryptography in C and C++Cryptography in C and C++, M. Welschenbach, Apress, , M. Welschenbach, Apress, ISBN 1-893115-95-X (includes code samples CD)ISBN 1-893115-95-X (includes code samples CD)

Copyright 2004 © Project Botticelli Ltd & Microsoft Corp. E&OE. For informational purposes only. No warranties of Copyright 2004 © Project Botticelli Ltd & Microsoft Corp. E&OE. For informational purposes only. No warranties of any kind are made and you have to verify all information before relying on it. You can re-use this presentation as any kind are made and you have to verify all information before relying on it. You can re-use this presentation as

long as you read, agree, and follow the guidelines described in the “Comments” field in File/Properties.long as you read, agree, and follow the guidelines described in the “Comments” field in File/Properties.

Thanks to Rafal Lukawiecki for providing some of the content Thanks to Rafal Lukawiecki for providing some of the content for this presentation deck – his contact details are as for this presentation deck – his contact details are as follows…follows…

rafal@projectbotticelli.co.ukrafal@projectbotticelli.co.uk

Strategic Consultant, Project Botticelli LtdStrategic Consultant, Project Botticelli Ltd