A Choreography-Driven Approach to APIs: The OpenDXL Case Study - - PowerPoint PPT Presentation

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A Choreography-Driven Approach to APIs: The OpenDXL Case Study - - PowerPoint PPT Presentation

Jun 13, 2023 215 likes •606 views

A Choreography-Driven Approach to APIs: The OpenDXL Case Study Leonardo Frittelli @ McAfee, Cordoba, AR Facundo Maldonado @ McAfee, Cordoba, AR Hern an Melgratti @ UBA, AR Emilio Tuosto @ GSSI, IT & UoL, UK Coordination 2020 15-20 July

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A Choreography-Driven Approach to APIs: The OpenDXL Case Study

Leonardo Frittelli @ McAfee, Cordoba, AR Facundo Maldonado @ McAfee, Cordoba, AR Hern´ an Melgratti @ UBA, AR Emilio Tuosto @ GSSI, IT & UoL, UK Coordination 2020 15-20 July 2020

Research partly supported by the EU H2020 RISE programme under the Marie Sk lodowska-Curie grant agreement No 778233.

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Prelude

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A fairy tale

(pictures from Matteo Garrone’s “Pinocchio”) Tell them...

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A fairy tale

(pictures from Matteo Garrone’s “Pinocchio”) and they’ll behave

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A fairy tale

(pictures from Matteo Garrone’s “Pinocchio”) unless they don’t

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A fairy tale

(pictures from Matteo Garrone’s “Pinocchio”) So, keep an eye on’em

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A fairy tale

(pictures from Matteo Garrone’s “Pinocchio”)

  • f course, it’s for their own good
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At a glance

API-based development

difficult in theory... ...and in practice

BehAPI

Behavioural specification of APIs can help

document monitor

Case study: OpenDXL

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Managing expectations

This work

reports on a collaboration with industry uses existing behavioural types proposes a methodology strives

to be easily usable by non-experts to attain practical benefits

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Managing expectations

No new technical contributions This work

reports on a collaboration with industry uses existing behavioural types proposes a methodology strives

to be easily usable by non-experts to attain practical benefits

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OpenDXL & Threat Intelligence Exchange

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Open Data Exchange Layer

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Architecture of OpenDXL

C Env C Env C Env B B S S S

Brokers abstracted away

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Architecture of OpenDXL

C Env C Env C Env S S S

Brokers abstracted away Event-based communication

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Architecture of OpenDXL

C Env C Env C Env S S S check

Brokers abstracted away Event-based communication

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Architecture of OpenDXL

C Env C Env C Env S S S res r e s res res

Brokers abstracted away Event-based communication

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An instance of OpenDXL services

TIE’s features

coordination of activities involving assessment of the security threats

  • f configuration files, certificates, unsigned or unknown files, etc.

prioritisation of analysis steps

focusing on malicious or unknown files

customisation of security queries

based on reputation-based data such as product or company names

reaction to suspicious indicators

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Documenting TIE

Semi-formal diagrams Verbal recommendations

a client “must have permission to send messages to the /mcafee/service/tie/reputation/set topic”

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Sounds good...in theory

In practice “Stuff” developed @McAfee works fine

McAfee provides the service and clients

but it’s a SOA: 3rd-party clients misbehave sometimes hence, defensive programming of TIE services

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Sounds good...in theory

In practice “Stuff” developed @McAfee works fine

McAfee provides the service and clients

but it’s a SOA: 3rd-party clients misbehave sometimes hence, defensive programming of TIE services

Caveat

3rd-party code may not be available for analysis Hence, post-mortem analysis of execution logs to identify misbehaviour and communicate it to 3rd-parties

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A methodology

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Idea

Adding more precision:

1 draw the protocol (global choreography) 2 turn the “drawing” into a behavioural type 3 project to component specs (local types) 4 turn local specs into state machines

Advantages

global choreographies: formal & precise (Pomset or Event Structure semanticsa), yet intuitive algorithmically generate monitors enhance “program comprehension”

aSee Ugo de’Liguoro’s talk @ ICE 2020

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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

  • C sends meta-data
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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

  • C requests an assessment
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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

  • nested choice
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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

  • S publishes a new report
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Let’s tie our TIE

After a couple of meetings...

C− →S: MD(x) S− →C: Restt(x) C− →S: MD(x) C− →S: File(x) S− →C: Resft(x) C− →S: File(x) S− →C: Restf(x) C− →S: MD(x) S− →C: Resff(x) + + C− →S: Req(x) + + KNR

  • DISCLAIMER

No greek letters were used in the making of this global view

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If you’re versed in behavioural types

Behavioural types

Suitable devices for specification and analysis focus on control (mostly) assume point-to-point channels

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If you’re versed in behavioural types

Behavioural types

Suitable devices for specification and analysis focus on control (mostly) assume point-to-point channels

vs

Klaimographies

Behavioural types with focus on data (mostly) interactions based on generative communication unit & multi-roles

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Monitors from projections

UML-like

@startuml left to right direction [*] --> S0 S0 --> S0: ’MD’ @l @Dgt S0 --> S1: ’Req’@l S1 --> S2: (’Res’, ’1’, ’1’)@l -> @Dgt S1 --> S3: (’Res’, ’0’, ’1’)@l -> @Dgt S1 --> S4: (’Res’, ’1’, ’0’)@l -> @Dgt S1 --> S0: (’Res’, ’0’, ’0’)@l S2 --> S3: ’MD’@l -> @Dgt S3 --> S0: ’File’@f S4 --> S0: ’MD’@l @enduml

Transformation Manual (for now) but algorithmic ’@...’ for data-flow analysis huge logs (can’t fit memory) Monitor checks expected data correspondences (e.g., ’file’ corresponds to a ’file req’)

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Lessons learned

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Effectiveness & Reproducibility (of (meta-)communication)

non-deterministic & visual abstractions

help communication among stakeholders provide insights & “inspirations”

but semantics is necessary

to attain precision to change mind

a reviewer was “missing the difficulties in this formalisation”

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Generality

how tight to TIE are we? klaimographies were not designed for OpenDXL a reviewer noted: “event-based middleware are becoming the norm” choreography can go bottom-up (as noted by another reviewer)

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Other FM?

Sure / but ... Model checking but it is not easy for lay-users to express properties in some temporal logic Other behavioural types usually too many greek letters Other FM (Petri nets, event structures,...) too low level (and (sadly) not much studied anymore)

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What’s next?

Tool support (extend ChorGram)

validated global views ensure properties automatise projections code generation (eg TIE vs many versions/variants)

Extend the application to other services of TIE / OpenDXL Klaimographies-inspired abstractions for CAS

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Thank you and to the anonymous reviewers!