1. Audit Trail and Node Authentication / Consistent Time
Robert Horn
Agfa Healthcare

2. Working Together to Deliver Interoperable Health Information Systems
W W W . I H E . N E T
Providers and Vendors
Working Together to Deliver
Interoperable Health Information Systems
In the Enterprise
and Across Care Settings
June 28-29, 2005
Interoperability Strategy Workshop

3. IT Infrastructure Profiles
Audit Trail and Node Authentication (ATNA) –Centralized privacy audit trail and node to node authentication to create a secured domain
Consistent Time (CT) – Coordinate time across network systems
2004
Patient Identifier Cross-referencing for MPI (PIX)
Retrieve Information for Display (RID)
Consistent Time (CT)
Patient Synchronized Applications (PSA)
Enterprise User Authentication (EUA)
2005
Patient Demographic Query (PDQ)
Cross Enterprise Document Sharing (XDS)
Audit Trail and Note Authentication (ATNA)
Personnel White Pages (PWP)
2006
Cross-Enterprise User Authentication (XUA)
Document Digital Signature (DSG) –
Notification of Document Availability (NAV)
Patient Administration/Management (PAM)
June 28-29, 2005
Interoperability Strategy Workshop

4. Interoperability Strategy Workshop
IHE and PHI Protection
User Identity → PWP, EUA
User Authentication → EUA, XUA
Node Authentication → ATNA
Security Audit Trails → ATNA
Data Integrity Controls → CT, ATNA TLS option
Data Confidentiality → ATNA TLS option
Access Controls → Future item in IHE roadmap
June 28-29, 2005
Interoperability Strategy Workshop

5. Audit Trail and Node Authentication (ATNA) Abstract / Scope
Defines basic security features for an individual system for use as part of the security and privacy environment for a healthcare enterprise.
Extends the IHE radiology oriented Basic Security profile (defined in 2002) to be applicable to other healthcare uses.
Provides host level authentication, which is used in conjunction with the user authentication from EUA and XUA.
June 28-29, 2005
Interoperability Strategy Workshop

6. ATNA Value Proposition
Protect Patient Privacy and System Security:
Meet ethical and regulatory requirements
Enterprise Administrative Convenience:
Unified and uniform auditing system
Common approach from multiple vendors simplifies definition of enterprise policies and protocols.
Common approach simplifies administration
Development and support cost reduction through Code Re-use:
Allows vendors to leverage single development effort to support multiple actors
Allows a single development effort to support the needs of different security policies and regulatory environments.
June 28-29, 2005
Interoperability Strategy Workshop

7. ATNA Security Requirements
Reasons: Clinical Use and Privacy
authorized persons must have access to medical data of patients, and the information must not be disclosed otherwise.
Unauthorized persons should not be able to interfere with operations or modify data
By means of procedures and security mechanisms, guarantee:
Confidentiality
Integrity
Availability
Authenticity
June 28-29, 2005
Interoperability Strategy Workshop

8. ATNA Security Measures
Authentication: Establish the user and/or system identity, answers question: “Who are you?”
ATNA defines: How to authenticate network connections.
ATNA Supports: Authentication mechanisms, e.g. Enterprise User Authentication (EUA) or Cross Enterprise User Authentication (XUA)..
Authorization and Access control: Establish user’s ability to perform an action, e.g. access to data, answers question: “Now that I know who you are, what can you do?”
ATNA defines: How to authorize network connections.
ATNA requires: System internal mechanisms for both local and network access.
June 28-29, 2005
Interoperability Strategy Workshop

9. ATNA Security Measures
Accountability and Audit trail: Establish historical record of user’s or system actions over period of time, answers question: “What have you done?”
ATNA Defines: Audit message format and transport protocol
June 28-29, 2005
Interoperability Strategy Workshop

10. Interoperability Strategy Workshop
ATNA IHE Goal
IHE makes cross-node security management easy:
Only a simple manual certificate installation is needed, although more sophisticated systems can be used
Separate the authentication, authorization, and accountability functions to accommodate the needs of different approaches.
Enforcement driven by ‘a posteriori audits’ and real-time visibility.
June 28-29, 2005
Interoperability Strategy Workshop

11. ATNA Integrating Trusted Nodes
Secured System
Secured System
Local access control (authentication of user)
Secure network
Strong authentication of remote node (digital certificates)
network traffic encryption is not required, it is optional
Audit trail with:
Real-time access
Time synchronization
Central
Audit Trail Repository
System A
System B
June 28-29, 2005
Interoperability Strategy Workshop

12. ATNA Suitable Network Environments
Physically secured networks
Explicit physical security preventing access by other nodes, or
VPN and VLAN technologies that provide equivalent network isolation.
Protected networks
Physical security that prevents modification or installation of unauthorized equipment
The network is shared with other authorized nodes within the enterprise that should not have unrestricted access to patient information.
Unprotected networks
Not generally supported, although nodes with sufficient node level security and using encryption may be safe.
June 28-29, 2005
Interoperability Strategy Workshop

13. Interoperability Strategy Workshop
ATNA Node Security
ATNA specifies some of the capabilities that are needed, e.g. access control.
ATNA does not specify policies
ATNA does not specify mechanisms, although other IHE protocols like EUA are obvious candidates.
This permits vendors and enterprises to select technologies and policies that are appropriate to their own purposes without conflicting with the ATNA profile.
June 28-29, 2005
Interoperability Strategy Workshop

14. ATNA Node Authentication
X.509 certificates for node identity and keys
TCP/IP Transport Layer Security Protocol (TLS) for node authentication, and optional encryption
Secure handshake protocol of both parties during Association establishment:
Identify encryption protocol
Exchange session keys
Actor must be able to configure certificate list of authorized nodes.
ATNA presently specifies mechanisms for HTTP, DICOM, and HL7
June 28-29, 2005
Interoperability Strategy Workshop

15. Why node authentication?
Many systems are shared access, e.g. CT systems, where the machine identity is more important than the operator’s identity for security purposes.
A CT operator is only permitted to update CT records from a CT system.
Some systems operate autonomously, e.g. PACS archive.
Knowing identity of the PACS administrator on duty is not useful when monitoring PACS activity. There might be nobody logged in.
Machine access is usually controlled by the site administration.
Even authorized users are not permitted to use personal machines.
June 28-29, 2005
Interoperability Strategy Workshop

16. Interoperability Strategy Workshop
ATNA Auditing System
Designed for surveillance rather than forensic use.
Two audit message formats
IHE Radiology interim format, for backward compatibility with radiology
IETF/DICOM/HL7/ASTM format, for future growth
DICOM Supplement 95
IETF Draft for Common Audit Message
ASTM E.214
HL7 Audit Informative documents
Both formats are XML encoded messages, permitting extensions using XML standard extension mechanisms.
June 28-29, 2005
Interoperability Strategy Workshop

17. Interoperability Strategy Workshop
ATNA Auditable Events
Actor-start-stop
The starting or stopping of any application or actor.
Audit-log-used
Reading or modification of any stored audit log
Begin-storing-instances
The storage of any persistent object, e.g. DICOM instances, is begun
Health-service-event
Other health service related auditable event.
Images-availability-query
The query for instances of persistent objects.
Instances-deleted
The deletion of persistent objects.
Instances-stored
The storage of persistent objects is completed.
June 28-29, 2005
Interoperability Strategy Workshop

18. Interoperability Strategy Workshop
ATNA Auditable Events
Medication
Medication is prescribed, delivered, etc.
Mobile-machine-event
Mobile equipment is relocated, leaves the network, rejoins the network
Node-authentication-failure
An unauthorized or improperly authenticated node attempts communication
Order-record-event
An order is created, modified, completed.
Patient-care-assignment
Patient care assignments are created, modified, deleted.
Patient-care-episode
Auditable patient care episode event that is not specified elsewhere.
Patient-record-event
Patient care records are created, modified, deleted.
June 28-29, 2005
Interoperability Strategy Workshop

19. Interoperability Strategy Workshop
ATNA Auditable Events
PHI-export
Patient information is exported outside the enterprise, either on media or electronically
PHI-import
Patient information is imported into the enterprise, either on media or electronically
Procedure-record-event
The patient record is created, modified, or deleted.
Query-information
Any auditable query not otherwise specified.
Security-administration
Security alerts, configuration changes, etc.
Study-object-event
A study is created, modified, or deleted.
Study-used
A study is viewed, read, or similarly used.
June 28-29, 2005
Interoperability Strategy Workshop

20. ATNA Record Audit Event
Reliable Syslog (RFC 3195) is the preferred transport for Audit Records, although BSD Syslog protocol (RFC 3164) is permitted for backward compatibility with Radiology Basic Security.
Audit trail events and content based on IETF, DICOM, HL7, and ASTM standards. Also, Radiology Basic Security audit event format is allowed for backward compatibility.
June 28-29, 2005
Interoperability Strategy Workshop

21. What it takes to be a secure node
The entire host must be secured, not just individual actors.
The entire host must have appropriate user access controls for identification, authentication, and authorization.
All communications that convey protected information must be authenticated and protected from interception. This means every protocol, not just the IHE transactions.
All health information activities should generate audit trails, not just the IHE actors.
June 28-29, 2005
Interoperability Strategy Workshop

22. What it takes to be a secure node
The Secure node is not a simple add-on of an auditing capability. The complete work effort includes:
Instrumenting all applications to detect auditable events and generate audit messages.
Ensuring that all communications connections are protected.
Establishing a local security mechanism to protect all local resources.
Establishing configuration mechanisms for:
Time synchronization using Consistent Time (CT) profile
Certificate management
Network configuration
Implement the audit logging facility
June 28-29, 2005
Interoperability Strategy Workshop

23. Interoperability Strategy Workshop
Consistent Time (CT)
Network Time Protocol ( NTP) version 3 (RFC 1305) for time synchronization
Actor must support manual configuration
Required accuracy: 1 second
Optionally Secure NTP may be used
Required for use of ATNA, EUA, XUA
June 28-29, 2005
Interoperability Strategy Workshop

24. Interoperability Strategy Workshop
More information….
IHE Web sites:
Technical Frameworks, Supplements
ITI V1.0, RAD V5.5, LAB V1.0
Non-Technical Brochures :
Calls for Participation
IHE Fact Sheet and FAQ
IHE Integration Profiles: Guidelines for Buyers
IHE Connect-a-thon Results
Vendor Products Integration Statements
June 28-29, 2005
Interoperability Strategy Workshop