Smart Card Authentication

Dan Usher Joel Ward

Who we are… What we’ve seen… Security Concerns in today’s world Why SmartCards? Authentication & Authorization of SharePoint IIS and SmartCards Implementation Considerations and Pitfalls

Dan Usher MCP, MCTS, Security+ SharePoint Architect and Implementation / Deployment Engineer UVA - BS Physics Joel Ward MCP, MCAD Solutions Developer and Architect Penn State - BA Integrative Arts

Large and Small SharePoint implementations Authentication schemas using SmartCard authentication integrated with Active Directory and third party SSO systems Extranet Enabled SmartCard SharePoint systems

Cyber Security Identity Theft Phishing Information Assurance

Strong Passwords Web of Trust Two Factor Authentication Biometrics

Confidentiality Integrity Authenticity Availability Non-repudiation

Stricter Password Policies Resetting Passwords More Often Password Enabled Screensavers …disruptions in your daily work …things aren’t quite as secure as they were

Simplicity… Source: http://go.spdan.com/pki

Simplicity… to the end user Provides a secure tamper resistant storage physical token Enables portability of credentials and private information similar to other Federated Identity… …like OpenID, Facebook Connect, Google OpenSocial, Microsoft Hailstorm A PIN is used …Security

Similar to a physical token Contains the same information It has an expiration date It can be revoked Provides for similar IA capabilities However… It can be exported It can be shared It can be purchased It can be stolen

Authentication IIS Username & Password Client Certificates ISAPI Filters Custom Membership Providers Federation (ADFS or Third Party Identity Handler) Authorization SharePoint Groups and Permissions AD / LDAP / Role Provider Security Groups

Handled by IIS and ASP.NET Checks user against AD or other auth provider Source: http://go.spdan.com/iisauth Passes verification to IIS to proceed ASP.NET Authentication

User attempts to access IIS X.509 Certificate on Smart User Enters PIN into User inserts smart card based site that requires Card with Private Key middleware software into reader smart auth verified locally prompt During Smart Card’s Public Key is Web Server receives public PIN authenticates user to authentication, challenge retrieved from card and key certificate and checks based on public key within verified through trusted the card validity against CA CRL certificate issued issuer Challenge verifies the card User’s identity from Public Key – Private Key Authentication has has a private key and that certificate UPN used to the private key can be Verified occurred reference user in AD leveraged Virtual Path Provider SharePoint verifies user’s IIS receives users identity Site is rendered to the end directs user to appropriate authorization to specific and hands them to user site site SharePoint

Option 0: SharePoint on an Intranet with integrated authentication Option 1: SharePoint in a DMZ with client certificates and AD integration Option 2a: SharePoint published through Internet Security and Acceleration (ISA) Server Option 2b: SharePoint published through Intelligent Application Gateway (IAG) Server Option 3: Custom Membership Provider

SharePoint is Intranet based only Client Desktop utilizes the “SmartCard Enabled Login Required” security policy setting SharePoint utilizing Integrated Windows authentication Kerberos or NTLM

Intranet only situation Need to be within the network boundary for authentication tokens to pass properly User’s account must be linked to their SmartCard user principal name Certificate Authority (CA) availability for CRL check may affect system availability

Web Server in DMZ Utilize Authentication Store (AD) IIS Configured to Require Client Certificate Relatively easy to configure

Install a SSL certificate that belongs to a managed PKI environment Within IIS in the specific web application, enable: Require Secure Channel (SSL) Require 128-bit encryption (optional) Require client certificate Certificate Revocation List (CRL) ports open LDAP or LDAP-S

OCSP or CRL checking could cause authentication to fail if CRL is not available Depending on number of requests, CRL checking could cause server load Puts server in DMZ, increases attack surface area – wfetch will show your SharePoint Version User’s account must be linked to their SmartCard user principal name User selecting certificate that does not contain UPN

Internet Security and Acceleration 2006 (ISA) Server Web Site Publishing with Constrained Kerberos Delegation Internal Windows Networking Infrastructure system utilizing Kerberos Users authenticate to their client machine using different account than SmartCard linked to their AD user object

Windows XP + Office 2007 requires a hot fix to allow for documents to open using ISA Increases authentication requirements for external facing or extranet systems User’s account must be linked to their SmartCard user principal name Multi-Forest trusts do not always work Reauthentication issues Only leverages Active Directory

Intelligent Application Gateway (IAG) Server Publishing Web Front End Server Similar to Option 2a (ISA Server), but better experience for the end user Stable session - Prevents constant requests for re-authorization using SmartCard Allows for NAP like capabilities Allows for mapping to something than AD

Additional hardware to maintain Current IAG is a hardware appliance IAG 2007 available as a virtual machine for demonstration purposes Future IAG will potentially be available as software and hardware IAG -> Forefront Unified Access Gateway (UAG) Costly Requires authenticating to IAG dashboard

Custom Membership provider for SmartCard IIS or SSO/ISAPI filter handshakes with the SmartCard Does not require Active Directory: Can use LDAP, SQL Server, or another authentication provider

Custom SharePoint login page (using Forms Based Authentication) completes the login process seamlessly without user input Can optionally create user account on the fly, based on SmartCard credentials Can add in logic for account approval, different access levels based on SmartCard credentials, etc.

Requires additional configuration in SharePoint Requires custom development If requiring client certificate in IIS (instead of SSO or ISAPI filter), OCSP or CRL checking could cause authentication to fail if CRL is not available Must secure server if in DMZ Must add in appropriate security logic to custom login page

1) Configure domain name and SSL certificate for web application 2) Implement Forms Based Authentication with SharePoint using appropriate membership and role provider (AD, LDAP, ASPNET, etc.) 3) Configure IIS to accept client certificates (or custom SSO) 4) Create custom login page for SharePoint _layouts folder

//Get client certificate and appropriate user ID HttpClientCertificate cert = Request.ClientCertificate; string userID; userID = cert.Get(quot;[fieldname]quot;); //Create new user and add to Visitor role MembershipUser user = Membership.CreateUser(userID,[randomPassword],[email]); Roles.AddUserToRole(userID, quot;Visitorsquot;); //If user exists in membership provider, login using FBA if (Membership.GetUser(userID).UserName == userID) FormsAuthentication.RedirectFromLoginPage(userID, false);

For SmartCard authentication to work properly, it relies heavily on the surrounding Windows networking infrastructure that it resides within SmartCard authentication can be done several different ways depending on the surrounding infrastructure SmartCards works well when the user base understands their responsibility in upholding IA.

Dan Usher dan@spdan.com http://www.sharepointdan.com @usher Joel Ward joel@wardworks.com http://joelsef.blogspot.com @joelsef

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Smart Card Authentication

by Dan Usher on May 03, 2009

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