IEC TR 62541-2:2016

IEC TR 62541-2 ®
Edition 2.0 2016-10
TECHNICAL
REPORT
colour
inside
OPC unified architecture –
Part 2: Security Model
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IEC TR 62541-2 ®
Edition 2.0 2016-10
TECHNICAL
REPORT
colour
inside
OPC unified architecture –
Part 2: Security Model
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.01 ISBN 978-2-8322-3641-3

– 2 – IEC TR 62541-2:2016 © IEC 2016
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references. 6
3 Terms, definitions and abbreviations . 8
3.1 Terms and definitions . 8
3.2 Abbreviations . 12
3.3 Conventions for security model figures . 12
4 OPC UA security architecture. 12
4.1 OPC UA security environment . 12
4.2 Security objectives . 13
4.2.1 Overview . 13
4.2.2 Authentication . 13
4.2.3 Authorization . 13
4.2.4 Confidentiality . 14
4.2.5 Integrity . 14
4.2.6 Auditability . 14
4.2.7 Availability . 14
4.3 Security threats to OPC UA systems . 14
4.3.1 Overview . 14
4.3.2 Message flooding . 14
4.3.3 Eavesdropping . 15
4.3.4 Message spoofing . 15
4.3.5 Message alteration . 15
4.3.6 Message replay . 15
4.3.7 Malformed Messages . 15
4.3.8 Server profiling . 16
4.3.9 Session hijacking . 16
4.3.10 Rogue Server . 16
4.3.11 Compromising user credentials . 16
4.4 OPC UA relationship to site security . 17
4.5 OPC UA security architecture . 17
4.6 SecurityPolicies . 19
4.7 Security Profiles . 20
4.8 User Authorization . 20
4.9 User Authentication . 20
4.10 Application Authentication . 20
4.11 OPC UA security related Services . 21
4.12 Auditing . 21
4.12.1 General . 21
4.12.2 Single Client and Server . 22
4.12.3 Aggregating Server . 23
4.12.4 Aggregation through a non-auditing Server . 23
4.12.5 Aggregating Server with service distribution . 24
5 Security reconciliation . 25
5.1 Reconciliation of threats with OPC UA security mechanisms . 25
5.1.1 Overview . 25

5.1.2 Message flooding . 25
5.1.3 Eavesdropping . 26
5.1.4 Message spoofing . 26
5.1.5 Message alteration . 26
5.1.6 Message replay . 26
5.1.7 Malformed Messages . 27
5.1.8 Server profiling . 27
5.1.9 Session hijacking . 27
5.1.10 Rogue Server . 27
5.1.11 Compromising user credentials . 27
5.2 Reconciliation of objectives with OPC UA security mechanisms . 27
5.2.1 Overview . 27
5.2.2 Application Authentication . 28
5.2.3 User Authentication . 28
5.2.4 Authorization . 28
5.2.5 Confidentiality . 28
5.2.6 Integrity . 28
5.2.7 Auditability . 28
5.2.8 Availability . 29
6 Implementation and deployment considerations . 29
6.1 Overview. 29
6.2 Appropriate timeouts . 29
6.3 Strict Message processing . 29
6.4 Random number generation . 29
6.5 Special and reserved packets . 30
6.6 Rate limiting and flow control . 30
6.7 Administrative access . 30
6.8 Alarm related guidance . 30
6.9 Program access . 30
6.10 Audit event management . 31
6.11 Certificate management . 31
Bibliography . 36

Figure 1 – OPC UA network model . 13
Figure 2 – OPC UA security architecture . 18
Figure 3 – Simple Servers . 22
Figure 4 – Aggregating Servers . 23
Figure 5 – Aggregation with a non-auditing Server . 24
Figure 6 – Aggregate Server with service distribution. 25
Figure 7 – Manual Certificate handling . 32
Figure 8 – CA Certificate handling . 33
Figure 9 – Certificate handling . 34

– 4 – IEC TR 62541-2:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPC UNIFIED ARCHITECTURE –
Part 2: Security Model
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory
...