September, 2005What IHE Delivers 1 G. Claeys, Agfa Healthcare ([email protected]) Audit Trail and Node Authentication.

1September, 2005 What IHE Delivers

G. Claeys, Agfa Healthcare G. Claeys, Agfa Healthcare ([email protected])([email protected])

Audit Trail and Node Audit Trail and Node AuthenticationAuthentication

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ScopeScope

Defines basic security features for a system in a healthcare enterprise in order to guarantee : Only authorized persons have access to PHI (Protected

Health Information) Protect PHI against alteration, destruction and loss Comply existing Privacy & Security regulations

Extends the IHE radiology oriented Basic Security profile (2002) to be applicable to other healthcare uses.

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Security MechanismSecurity Mechanism

Authentication (user and device)

Authorization

Accountability (audit trails)

Confidentiality

Integrity

ATNA, EUA

ATNA

ATNA

ATNA

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IHE ATNA- Architecture

System A System B

Secured SystemSecure network

Secured System

Central Audit TrailRepository

Secure network

• Local authentication of user• Strong authentication of remote node (digital certificates)• Audit trail that logs privacy&security related operations

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All existing IHE actors need to be grouped with a Secure Node actor.

Secure Node

Audit RecordRepository

“Any” IHE actor

Record Audit Event

Time Server

Secure Node Authenticate Node

Maintain Time

IHE ATNA – Actor and TransactionsIHE ATNA – Actor and Transactions

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Secure NodeSecure Node

Local user authentication Only needed at “client” node Authentication mechanism

• User name and password (minimum)• Biometrics, smart card

Secure nodes maintain list of authorized users : local or central (using EUA)

Security policy of hospital defines the relation between user and user id

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Secure Node (cont.)Secure Node (cont.)

Mutual device authentication Establish a trust relationship between 2 network nodes Strong authentication by exchanging X.509 certificates Actor must be able to configure certificate list of trusted nodes.

TCP/IP Transport Layer Security Protocol (TLS) Used with DICOM/HL7/HTTP messages Secure handshake protocol during Association establishment: Encryption :

• Intra-muros (default): no encryption • Extra-muros : AES128

TLS/SSL negotiations problems were detected at connectathon 2006 USA Caused by incorrect configuration of SSL/TLS packages (e.g.

STunnel) Guidelines will follow

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Secure node – additional effortSecure node – additional effort

Instrument all applications to detect auditable events and generate audit messages.

Ensure that all communications connections are protected (system hardening).

Establish a local security mechanism to protect all local resources

Establish configuration mechanisms for: Time synchronization Certificate management Network configuration

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Certificate ManagementCertificate ManagementCertificates can be signed by device (self-signing) or via a CA (e.g. hospital) Use self-signed certificates for testing interoperability Connectathon has a CA

Support at least direct comparison of certificates Import certificate of each trusted peer device Compare each received certificate with list of trusted

certificate

Certificate management white paper from NEMA’s Security&Privacy committee www.nema.org/prod/med/security

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Auditing SystemAuditing System

Auditing system consists of List of events that generate audit messages Audit message format Transport mechanism

Designed for surveillance rather than forensic use.

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Audit EventsAudit Events

Audit triggers are defined for every operation that access PHI (create, delete, modify, import/export)

IHE TF describes the supported Audit Trigger per Actor

Audit triggers are grouped on transaction/ study level to minimize overhead

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Audit Message FormatAudit Message Format

XML encoded message

IHE Radiology Provisional format for backward compatibility with radiology

ATNA format Preferred format Joint effort of IETF/DICOM/HL7/ASTM XML schema (rfc3881) :

www.xml.org/xml/schema/7f0d86bd/healthcare-security-audit.xsd

XSLT transformation is provided to convert “Provisional scheme” to “ATNA” scheme

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Audit Transport MechanismAudit Transport Mechanism

Reliable Syslog – cooked mode RFC 3195 Connection oriented Support certificate based authentication,

encryption But limited industry support

BSD Syslog protocol (RFC 3164) Preferred transport mechanism for the time being

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Backward compatibilityBackward compatibility

ATNA is backward compatible with Basic Security (IHE Radiology) Basic security = Provisional XML scheme + BSD syslog Applications, supporting Basic Security are ATNA compliant

Basic security is deprecated Basic Security Profile being deprecated by Radiology Option

for ATNA No further extensions New applications are encouraged to use new message

format

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Audit system - lessons learnedAudit system - lessons learned

BSD Syslog Ensure that the BSD header format is correct, otherwise the

messages may get trashed. BSD Syslog messages longer than 1k may get truncated

• -> keep the messages short

Date/Time : UTC format EventDateTime="2006-01-17T17:01:25-06:00“ or EventDateTime="2006-01-17T17:01:25-06:00Z“

Patient ID Use either the MRN (preferred) or a properly defined local

Patient ID. Patient Names can be arbitrary format.

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Audit system - lessons learned (cont.)Audit system - lessons learned (cont.)

Active Participant Identification Use one ActiveParticipant per event Use an identifiable user as ActiveParticipant If not possible then use the node/process as

ActiveParticipant

Node names Use host names instead of ip addresses

Audit Source Id : hostname or stationName

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Audit system - lessons learned (cont.)Audit system - lessons learned (cont.)

Event Identification (EventID): use DCM code set (DICOM supplement 95) or IHE

code set (ATNA) avoid proprietary values.

Schema checking Ensure that the messages conform to the schema

defined in RFC3881 Do not include schema items with null contents.

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www.ihe-europe.orgwww.ihe-europe.org

Frequently Asked QuestionsFrequently Asked Questions

Integration Profiles in Technical Frameworks:Integration Profiles in Technical Frameworks: CardiologyCardiology IT InfrastructureIT Infrastructure LaboratoryLaboratory Patient Care CoordinationPatient Care Coordination RadiologyRadiology

Connectathon ResultsConnectathon Results

Vendor Products Integration StatementsVendor Products Integration Statements

Participation in Committees & ConnectathonsParticipation in Committees & Connectathons