Modeling a System Flashcards
(39 cards)
1
Q
What is a data flow diagram?
A
- diagrams that describe the flow of data among components in a system as well as properties of the components and flow
2
Q
What are sequence diagrams?
A
- diagrams that describe the interactions of components in an ordered manner.
3
Q
What are sequence diagrams useful in identifying threats?
A
- They allow a designer to understand the state of the system over time
4
Q
What are process flow diagrams used for?
A
- They highlight the operational flow through actions among components in a system
5
Q
What are attack trees?
A
- They depict the steps along a path that an attacker might try as part of reaching their goal to perform actions with nefarious intent
6
Q
What are fishbone diagrams?
A
- They show the relationships between an outcome and the root cause(s) that enabled such an effect to occur
7
Q
When developing a DFD what are some common annotations used for elements?
A
- Name of unit
- Owner
- If a process what privilege is it running at
- If it’s a binary object is it expected to be signed?
- What programming languages are used?
- For managed/interpreted code what runtime/bytecode processor is used
8
Q
What is an element in the context of a DFD?
A
- A shape that represents a process or operating unit within the system
9
Q
What is a container in the context of a DFD?
A
- A unit in the system that contains additional elements and flows
10
Q
What is a context layer in a DFD?
A
- A DFD diagram that represents a high level view of a system and it’s interactions with external entities(e.g., remote systems or users)
11
Q
Where is a container used in a DFD?
A
- in a context layer DFD
12
Q
What is an external entity in the context of a DFD?
A
- It represents a process or system that is involved in the operation or function of the system but is not in scope for the analysis
13
Q
What is a data store in the context of a DFD?
A
- represents where bulk data is stored, a message bus, or a shared memory region
14
Q
What are some examples of data represented by a data store in the context of a DFD?
A
- database
- file or buffer holding small amounts of security relevant data
- logfile output
15
Q
What are some meta data that should be captured for a data store in the context of a DFD?
A
- Type of storage - file, S3 bucket, service mesh, shared memory region
- Type and classification of data held - structured/unstructured, data format
- Sensitivity or value of data
- Protections on the data store itself
- Replication - is data replicated to a different data store
- Backup - is data copied to another place for safety but with reduced security and access controls
16
Q
What are data flow symbols in the context of a DFD?
A
- They describe where and how interactions are made among entities.
17
Q
What is the primary purpose of a data flow symbols in the context of a DFD?
A
- They describe the primary direction of travel of communications that is relevant for the purposes of analysis.
18
Q
What should be conveyed with data flow elements in the context of a DFD?
A
- Application-level data or control messages that are being passed on an established channel
19
Q
What meta data should data flows be assigned in the context of a DFD?
A
- Type or nature of channel - IPC, Network
- Protocols in use - HTTP, gRPC, TCP/IP, HTTPS
- Data being communicated
- Order of operations(if useful)
20
Q
What is a “trust boundary” in the context of a DFD?
A
- Shows objects and entities operating within the boundary that operate at the same trust level
21
Q
What is a “block element” in the context of a DFD?
A
- An architectural element that selectively alters the data flow on which it is attached
22
Q
What are examples of “block elements” in the context of a DFD?
A
- a host firewall, another physical device, a logical mechanism as a function of the architecture
23
Q
What meta data is associated with “block elements” in the context of a DFD?
A
- Type of block - a physical or logical device and whether it’s optional
- Behavior - what the block does and how it may modify the flow or access to a port or process
24
Q
What is an “Attack Tree”?
A
- A modeling technique used to understand how a system is vulnerable to attackers influencing a system
25
When is an “Attack Tree" used in modeling a system?
* When performing threat analysis from an attacker-centric perspective
26
What outcome is an “Attack Tree" meant to show?
* A positive outcome for an attacker and a negative outcome for the system owners
27
In order for an “Attack Tree" to provide the correct analysis of impact what is needed?
* A complete knowledge of how something can be compromised
* Understanding motivation, skills, resources available to different types and groups of attackers
28
What are the first steps in creating a system model?
* Identify the major building blocks in the system
29
What are some examples of major building blocks in a system?
* Applications
* Servers
* Databases
* Datastores
30
When building a system model - After major building blocks are defined what is next?
* Identify the connections to each building block
31
When building a system model - What are examples of connections between databases?
* Clients of a database and the privilege they have
* Access control to the database
32
When building a system model - What are examples of connections to servers?
* Ports that a server listens on.
* Protocol used when communicating with the port
33
When building a system model - What are examples of connections between applications?
* Application API/UI
34
When building a system model who should be involved with the exercise?
* Lead Architect
* Designers
* Development leads
* QA lead
35
What properties should a ‘good’ model have?
* Accurate
* Meaningful
* Representative
* Living
36
What are the attributes that support a ‘good’ model being ‘accurate’?
* Its free of inaccurate or misleading information that will result in an imperfect threat analysis
37
What are the attributes that support a ‘good’ model being ‘meaningful’?
* Captures information that points to conditions for potential compromise
* It creates a representation of the system without recreating it.
* Provides sufficient data to make inferences and direct judgments on the characteristics of the system
38
What are the attributes that support a ‘good’ model being ‘representative’?
* Should represent the design intentions of the Architect or the realized implementation by the dev teams
39
What are the attributes that support a ‘good’ model being ‘living’?
* It's updated on a regular basis to ensure accuracy i.e., It should represent ‘what is’ and not ‘what it should be’
