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✅ SSDA Exam 1 | 100% Correct Answers | Verified 2025/2026, Exams of Software Development

Carnegie Mellon University (CMU)Software Development

Ace SSDA Exam 1 with this fully verified 2025/2026 answer set, covering foundational definitions and concepts in secure software development. Understand software as a collection of abstract, evolving artifacts—custom or generic—and learn how security practices ensure systems behave as expected in complex environments. Perfect for students of cybersecurity, software architecture, and systems design. Português: Respostas 100% corretas sobre design de software seguro e conceitos fundamentais. Español: Respuestas verificadas sobre diseño y arquitectura de software seguro. Italiano: Risposte corrette sull'esame di progettazione e architettura software sicura (SSDA). Tags: SSDA exam answers, secure software design, software characteristics, cybersecurity basics, logical systems, Carnegie Mellon University, verified 2025

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2024/2025

Available from 06/10/2025

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SSDA Exam 1 | Questions & Answers |
100% Correct | Verified
What is software? - ✔✔Software is a collection of abstract artifacts.
What are some characteristics of software? - ✔✔
- Either customized or generic.
- Software is a logical system.
- Software evolves.
What is security? - ✔✔The practices used to ensure the software works as expected considering the
environment and all possible inputs.
Why are we interested in security? - ✔✔
- No matter the system, there are things that must maintain their integrity: algorithms, user data, system
data.
- Low security leads to low trust.
What does CIA Triad stand for? - ✔✔Confidentiality, Integrity, Availability
What is the CIA Triad? - ✔✔- Three principles to which most vulnerabilities can be associated with. If we
secure all three, we can confidently place trust in the system and its security.
- Sometimes includes Accountability or Non-repudiation.
What is confidentiality? (examples too) - ✔✔- Privacy
- Separation between people who should be able to access data and those who shouldn't.
- Ex: encryption, authentication, separation
What is integrity? (examples too) - ✔✔- "Trustworthiness" of the software
SSDA 1
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Download ✅ SSDA Exam 1 | 100% Correct Answers | Verified 2025/2026 and more Exams Software Development in PDF only on Docsity!

SSDA Exam 1 | Questions & Answers |

100% Correct | Verified

What is software? - ✔✔Software is a collection of abstract artifacts. What are some characteristics of software? - ✔✔

  • Either customized or generic.
  • Software is a logical system.
  • Software evolves. What is security? - ✔✔The practices used to ensure the software works as expected considering the environment and all possible inputs. Why are we interested in security? - ✔✔
  • No matter the system, there are things that must maintain their integrity: algorithms, user data, system data.
  • Low security leads to low trust. What does CIA Triad stand for? - ✔✔Confidentiality, Integrity, Availability What is the CIA Triad? - ✔✔- Three principles to which most vulnerabilities can be associated with. If we secure all three, we can confidently place trust in the system and its security.
  • Sometimes includes Accountability or Non-repudiation. What is confidentiality? (examples too) - ✔✔- Privacy
  • Separation between people who should be able to access data and those who shouldn't.
  • Ex: encryption, authentication, separation What is integrity? (examples too) - ✔✔- "Trustworthiness" of the software
  • We should have a level of confidence in the data being dealt with.
  • Ex: access control systems, physical shielding, checksums, redundancy What is availability? (examples too) - ✔✔- A service or data should be available to those who should have access to it.
  • Often a hardware trait
  • Ex: increasing bandwidth, backup systems, distributed systems (DOS mitigation techniques) What is accountability/non-repudiation? (examples too) - ✔✔- Access to data should be traceable
  • Ex: logging, auditing What are the 3 growing trends that make systems susceptible to software security problems? - ✔✔Connectivity, Extensibility, Complexity What is connectivity? - ✔✔- More devices
  • Internet
  • IoT What is extensibility? - ✔✔Code is made to easily adapt or extend (plugins) What is complexity? - ✔✔- Growing technology dependency - > growing complexity
  • Growing complexity - > more room for error What are vulnerabilities of these growing trends? - ✔✔Bug, defect, fault, risk How can we ensure and maintain CIA? - ✔✔Secure software development & Secure software analysis What is Secure Software Development? - ✔✔- Create quality software with security in mind
  • Security should not be applied after the fact (i.e. penetrate and patch)

Complex vs. Complicated - ✔✔Complex:

  • Many components Complicated:
  • Difficult to understand
  • A complicated system may not be complex Open Design features - ✔✔- The security of a mechanism should not depend on the secrecy of its design or implementation
  • Common practices are good
  • Does not necessarily hinder security Examples of Open Design - ✔✔- Public key encryption
  • Role-based Access Control
  • Open source software/hardware Iterative Model - ✔✔- Multiple mini-waterfall-like cycles
  • A working implementation after each iteration
  • Requirements gathering spread out over iterations
  • Usually with less non-essential artifacts produced Incremental Model - ✔✔- Incrementally improve the software in small steps
  • Customer feedback
  • Less cumbersome than waterfall (fix mistakes quickly)
  • Working product delivered at each iteration (functionality delivered based on importance to client or development process)
  • Adaptable: plan-driven, flexible
  • Problems: difficult for large systems, can be chaotic for large teams Least Astonishment - ✔✔- Not the same thing as simplicity
  • Design should be intuitive and unsurprising
  • If a user does not understand the software, they won't use it correctly
  • Generally UI-oriented
  • Minimize learning curve
  • Sometimes difficult - > Security vs. Usability Attack through Astonishment - ✔✔Malware often takes advantage of this principle, if a user is astonished, it is likely they will do the wrong thing Security Design Principles - ✔✔- Minimize Secrets
  • Complete Mediation
  • Fail-Safe Defaults
  • Least Privilege
  • Economy of Mechanism
  • Least Common Mechanism
  • Separation of Duty Minimize Secrets - ✔✔- Secrets should be few and changeable
  • Secrets probably won't remain secret for long
  • Additional secrets increase administrative burden Complete Mediation - ✔✔- All accesses to all objects must be mediated (checked) to be sure they are allowed Fail-Safe Defaults - ✔✔- If the access fails, the system is not compromised (deny access by default) Least Privilege - ✔✔- Entities should only have the minimal rights necessary to perform a task
  • Works closely with fail-safe defaults
  • It may work to give everyone root access, but then they have access to everything

An architectural style describes: - ✔✔Software components:

  • Details hidden (data structures and algorithms)
  • Services displayed (how they use, are used by, relate to, and interact with other components) Relationships among the components:
  • Data flows
  • Control flows An architectural style determines: - ✔✔- The vocabulary of components and connectors that can be used in instances of that style
  • A set of constraints on how they can be combined Software architectures are represented as ... - ✔✔Graphs Nodes represent ... - ✔✔Components Edges represent ... - ✔✔Connectors What is Pipe and Filter? - ✔✔- Suitable for applications that require a defined series of independent computations to be performed on ordered data
  • A component reads streams of data on its input and produces streams of data on its outputs What are the components and connecters in pipe and filter? - ✔✔- Components: called filters, apply local transformations to their input streams and often do their computing incrementally so that output begins before all input is consumed
  • Connectors: called pipes, serve as conduits for the streams, transmitting outputs of one filter to inputs of another Constraints of pipe and filter? - ✔✔- Filters do not share state with other filters
  • Filters do not know the identity of their upstream or downstream filters

Examples of pipe and filter - ✔✔- Unix shell scripts

  • Traditional compilers Advantages of pipe and filter - ✔✔- Easy to understand the overall input/behavior of a system as a simple composition of the behaviors of the individual filters
  • Supports reuse, since any two filters can be hooked together, provided they agree on the data that is being transmitted between them
  • Complex without being complicated
  • Systems can be easily maintained and enhanced, since new filters can be added to existing systems and old filters can be replaced by improved ones
  • They permit certain kinds of specialized analysis, such as throughput and deadlock analysis
  • They naturally support concurrent execution Disadvantages of pipe and filter - ✔✔- Not good for handling reactive systems, because of their transformational characteristics
  • Excessive parsing and encoding leads to loss of performance and increased complexity in writing the filters themselves What is Distrustful Decomposition? - ✔✔- Goal: separate functions into completely separate programs/objects
  • Least privilege for each component
  • Similar to pipe and filter (filters can be separate programs)
  • Separation of duties => isolation of vulnerabilities What are the components and connectors of distrustful decomposition? - ✔✔- Components: individual programs making up the entire system (usually have a unique user ID running the process, could be file system itself)
  • Connectors: function calls or API between components Advantages of distrustful decomposition - ✔✔- Becomes difficult to compromise entire system (b/c of least privilege)
  • Increases modularity (if one module fails, the problem is contained at the code level)

Describe the Model, View, and Controller in MVC pattern - ✔✔Model:

  • Manages behavior and data of the application domain
  • Responds to requests for information about its state
  • Responds to instructions to change state
  • Often implemented with Object Relational Mapping (ORM) View:
  • Manages the display of information
  • Typically changes when an object changes state Controller:
  • Interprets input from user, controlling the model and/or view to change in response
  • Stores business logic MVC consequences - ✔✔- Data-centric design
  • Views can be easily updated without affecting business logic (modularity)
  • Models can be added as new objects (modularity)
  • Models are predetermined
  • Ease of maintainability What is a pattern? - ✔✔- A pattern is a solution to a recurring problem in a specific context
  • Patterns are like templates
  • Not code reuse What is the Gang of Four? - ✔✔A book of 23 design patterns What are the pattern types? - ✔✔Creational:
  • Techniques for creating objects
  • Configure classes Structural/Architectural:
  • Techniques for organizing objects
  • Separation of interface and implementation Behavioral:
  • Techniques for object communication
  • Class responsibility Singleton Pattern - ✔✔Problem: An object should only be allowed one instantiation within the system. Context: Object-oriented system where a class abstraction has one instance. Solution: make the class constructor private and provide a static method to the instance. Consequences of Singleton - ✔✔Controlled instantiation, Restricted instantiation (abstract) Factory Pattern? - ✔✔Problem: Object instantiation needs to be decided at runtime or many constructors exist and may change. Context: Object-oriented system Solution:
  • Create an interface class for all classes which may be instantiated
  • Create a Factory class which, depending on how it's invoked, will create and return a corresponding implementation of the abstract class
  • Client code only needs to access Factory Abstract Interface Class - ✔✔- Specifies interface and basic behavior of all objects returned by the factory
  • Creation behavior is specified by subclasses
  • Constructors can exhibit polymorphism (many constructors for individual classes) Factory Class - ✔✔- Removes direct use of constructors
  • Handles instance management
  • Usually just a single method

Consequences of Decorator - ✔✔- Different types of functionality can be grouped into decorators instead of core class

  • Simplified extensions
  • Better testing Observer Pattern - ✔✔Problem: Many objects rely on the state of a central object. Context: Situation with one-to-many dependencies. Solution:
  • Create an object called subject which notifies dependent observer objects of state changes (directly or indirectly)
  • Observers typically serve as "views"
  • Subject calls methods in observers to notify them of state change
  • Subject maintains a list of all its observers Publisher-Subscriber Pattern - ✔✔- Similar to observer pattern: publisher is like the subject, subscriber is like the observer
  • However, in pub-sub, neither component knows about the other component
  • Utilizes implicit invocation
  • A third component (broker or event bus) handles the message passing Benefits of using Patterns - ✔✔- Reuse
  • Documentation
  • Expert knowledge
  • Common vocabulary Single Access Point - ✔✔Problem: a system needs to be accessible by multiple users/systems in a secure way Context: isolated systems with a need to communicate with external entities Solution: provide a single interface for all communication with a system, secure that interface

Having multiple entry points providers multiple possibilities for exploitation A single entry point reduces complexity Session Pattern - ✔✔Problem: global information is stored in various places. Context: multi-user system Solution: store much information in a session object on per-user basis Solution: store such information in a session object on a per-user basis Internal checks can then be done based on the session. Typically done at login.