Discussing “Developing Secure Systems with UMLSec” 15 FEB Joe Combs

What Problem are we Trying to Solve? Blindly inserting security mechanisms into a system doesn’t work Need to bring efforts to mitigate these design limitations before system is actually implemented

Introducing UMLSec Extension of Unified Modeling Language - de-facto standard for OO development Attempt to encapsulate & make available to developers knowledge on prudent security engineering Encapsulation and modularity makes OO systems very well suited to considering security

UML Diagrams of Interest Use Case - typical interaction between user and system Activity - workflow modeling/detailed explanation of use case Class - static structure of the system Interaction - sequence or collaboration diagram describes interaction between objects via message exchange State Chart - dynamic component behavior within an object Package - groups parts of a system into higher level units Deployment - describes physical arrangement in a real-world instance

UMLSec Notation Stereotypes > Extensibility mechanism used to create meta-information about an entity in the diagram Tag-Value Pairs {tag,value} Extensibility mechanism to describe a property of a model element

Use Case Diagram >: if “buys goods” then eventually “sells goods”

Activity Diagram Solution on right gives fair exchange if payment is >

Class Diagram Ensure class structure provides data security Key::newkey() guarantees confidentiality & integrity but random does not!

Interaction Diagram Purchase system sends Init message to access card passing a session key signed with M’s private key and encrypted with C’s public key C decrypts the session key with its private key and verifies signature with M’s public key Once session key has been verified in this way, C can encrypt and send secrets using the session key and pass to M on the Resp message

State Chart Diagram Ensure behavior within a component - access control, database security, etc. Transition labels: events - message called on this object [conditions] - must be true for transition to fire \actions - carried out if transition fires

Package Diagram Uses visibility of parts within packages to reason about access privileges

Deployment Diagram Express security requirements on physical layer of the system: communication links hardware security etc.

Security Patterns Operation rx() leaks information on the account balance

The Wrapper Pattern Ensures no low read after a high write

Now What? UMLSec provides a mechanism for communicating security concerns, bringing security up to the requirements and design phases of the lifecycle Where can this go from here? Incorporate UMLSec notation for association, generalization, etc. Formal methods approaches?