Abhay Bhargav
July 3, 2024

How to Keep Your Software Secure with Ongoing Threat Modeling

Isn’t it odd that despite all the technological advancements, security breaches still continue to happen? 

Usually, the problem is the gaps in the Software Development Life Cycle (SDLC). One is the lack of integrated Threat Modeling.

So what is Threat Modeling? It's the ‘proactive’ approach to finding potential security threats and vulnerabilities during the design and development phases of software. Organizations that adopt threat modeling have their development team building more secure applications because they anticipate and solve threats early.

But it's easier said than done, many organizations find it hard to integrate threat modeling into their SDLC because:

  • threat modeling is complicated and time-consuming.
  • developers don't have enough security training.
  • teams are so used to their workflows, that they're not willing to adopt new processes.

In fact, 67% of developers admit that they don’t consistently include security in their SDLC processes.

Here's one of the solutions that I think will solve these challenges: streamlined threat modeling processes that are easy to understand and implement. If only these organizations would make a stand to integrate security into their SDLC, then we can have applications that are more resilient to threats and with barely any vulnerabilities. Read on to find out how to make this happen.

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Table of Contents:

  1. The Software Development Lifecycle and Its Phases
  2. How to Integrate Threat Modeling into Each Phase of the SDLC
  3. Why Regular Repetition is Needed in Threat Modelingsome text
    1. Periodic Threat Modeling
    2. Cyclical Threat Modeling
  4. Stay Ahead of Potential Threats and Adapt to New Risks

The Software Development Lifecycle and Its Phases

Before anything else, let's talk about the key phases of the SDLC itself. Each phase is dedicated to achieving one goal aimed at solving user problems and making sure of the delivery of a secure, functional product.


The requirements phase is all about gathering and analyzing what the users need from the software. Here's what this phase involves:

  • identifying user needs and expectations
  • documenting functional and non-functional requirements
  • defining project scope and objectives

The goal here is to create a clear, detailed specification that will serve as the blueprint of the development process and make sure that the final product meets user needs and expectations.


This is when the developers will do actual coding and create the software. The development phase includes:

  • writing and compiling code
  • building the software based on the requirements
  • conducting initial testing by developers

Here is when the requirements will become a working software application. This phase is all about the software’s functionality and performance.


The Verification phase is focused on making sure that the software meets all the defined requirements and is free of defects. Here's what the verification phase includes:

  • conducting thorough testing (unit, integration, system, and acceptance testing)
  • finding and fixing bugs
  • validating that the software performs as expected

Make sure that the software is reliable, secure, and ready for deployment. This phase is important for catching issues that could compromise security or functionality before the software goes live.


The application is now ready and released for use. Here's what these phase involves:

  • finalizing deployment configurations
  • conducting final security testing
  • performing a security audit
  • monitoring initial performance

The goal here is to verify that the software is securely deployed and operates as intended in its live environment to minimize the risk of security breaches.

How to Integrate Threat Modeling into Each Phase of the SDLC

Here's what I know: Organizations can no longer afford to put security on the back burner. It should be a foundational aspect of the development process. It all makes sense, right? Addressing potential threats early and continuously throughout the lifecycle will allow teams to address the risks before they become critical issues. It's a proactive approach that will improve the overall security posture of the final product. But that isn't the only benefit: your dev teams will continue to have a security-focused mindset for future projects to come. Here's how to integrate Threat Modeling into each phase of the SDLC:

Requirements Phase

Threat Modeling in the Requirements Phase will help identify potential security threats early for the establishment of robust security requirements and objectives that will guide the entire development lifecycle.

Key Question: "What are we working on?"

  1. Define the scope of the project to understand its boundaries and constraints.
  2. Create diagrams to visualize the system and its interactions.
  3. Break down existing systems to understand current security measures and vulnerabilities.
  4. Establish clear security requirements and objectives to guide the development process.

Development Phase

During the Development Phase, Threat Modeling makes sure that security is baked into the software instead of being added just because. Teams will anticipate what can go wrong and implement necessary mitigation techniques while adopting a security-first mindset throughout the coding process.

Key Question: "What can go wrong?"

  1. Find potential threats and vulnerabilities that could impact the software.
  2. Develop and implement strategies to mitigate the threats that you find.
  3. Use security checklists to make sure that all necessary measures are in place.
  4. Integrate security practices into the deployment process.
  5. Educate the development team on security best practices and potential threats.
  6. Make sure that security defaults are enforced throughout the development process.
  7. Secure the software supply chain to protect against third-party vulnerabilities.

Verification Phase

This phase involves rigorous testing and analysis to verify that all potential security threats have been addressed. Threat Modeling here will help teams assess how effective their security measures were, and if needed, this is when they make necessary adjustments.

Key Question: "What are you going to do about it?"

  1. Create test cases to evaluate the security of the software.
  2. Find any gaps between the current security measures and the desired security state.
  3. Analyze the software for potential vulnerabilities by conducting vulnerability analysis.
  4. Assess the software architecture to make sure it meets security standards.
  5. Check the software configuration for security compliance and best practices.

Deployment Phase

Practicing Threat Modeling during this phase helps make sure that all security measures are correctly implemented and that any last-minute vulnerabilities are addressed before the software goes live.

Key Question: "Did we do a good enough job?"

  1. Conduct the final comprehensive security testing to verify that all identified vulnerabilities have been addressed and that the software is secure.
  2. Review deployment configurations to make sure that they are secure and align with security best practices.
  3. Perform a thorough security audit to confirm that all security requirements have been met and no new vulnerabilities have been introduced.
  4. Implement monitoring to quickly identify and respond to any security issues that arise during the initial deployment.
  5. Ensure that deployment procedures include necessary security steps and that all team members are aware of their responsibilities.

These questions are actually from Adam Shostack's approach to Threat Modeling. Once you integrate these for every phase of SDLC, you'll have a more straightforward framework for incorporating security considerations throughout the development process. It makes Threat Modeling simpler because you'll be breaking it down into manageable steps that will make it accessible even for teams with limited security expertise. It guarantees that security is continuously evaluated and reinforced.

Join our "Rapid Threatmodeling with GenAI & LLMs" bootcamp to learn how to streamline and enhance your threat modeling efforts using the latest in AI technology. Sign up here: https://www.appsecengineer.com/rapid-threat-modeling-with-genai-and-llms

Why Regular Repetition is Needed in Threat Modeling

The simple answer is: for maintaining and improving software security. Regular repetition in Threat Modeling will help organizations adapt to new vulnerabilities and changing environments because you're continuously evaluating and addressing potential threats as the software develops. Here are two methods for incorporating regular repetitions in Threat Modeling:

Periodic Threat Modeling

Periodic Threat Modeling is when you conduct Threat Modeling exercises at regular intervals, regardless of the development cycle. You will make sure that the applications are consistently evaluated for security threats, even if they are not currently undergoing significant changes. Here are the benefits:

  • Regular intervals mean that security evaluations are not tied to specific development milestones.
  • Helps in adapting to new security threats that emerge over time.
  • Many regulatory frameworks and security best practices recommend or require periodic security assessments.
  • Helps better planning and allocation of resources to address security concerns proactively
  • Provides a wealth of historical data that can be analyzed to identify trends and improve future threat modeling efforts


  1. Set a fixed schedule (e.g., quarterly, biannually) for Threat Modeling sessions.some text
    1. What's the scope of each session? You need to know which parts of the application will be reviewed.
    2. Then collect all relevant data and documentation from the development and operational teams.
  2. Conduct thorough assessments that include all components of the application.some text
    1. Work with cross-functional teams to make sure that you find all potential threats.
    2. Use Threat Modeling tools and frameworks to assist in identifying and documenting threats.
  3. Maintain detailed records of findings, and don’t forget follow-up actions are taken to address any threats.some text
    1. Develop and assign action plans for mitigating identified risks.
    2. Use project management tools to track the progress of remediation efforts.

Cyclical Threat Modeling

Cyclical Threat Modeling integrates Threat Modeling into each phase of the development cycle. During this phase, you will need to make sure that security considerations are continuously addressed as the software develops. Here are the benefits:

  • Security practices will be baked into the development process
  • Involves cross-functional teams in the Threat Modeling process that actually helps in creating a security-first culture throughout the organization
  • There will be immediate actions once you detect threats that will reduce the risk of vulnerabilities making it into production
  • Improves the ability to respond swiftly to new threats as you discover them during the development process
  • Integrates security checks within development milestones


  1. Perform Phase-specific Threat Modeling during important phases of the development cycle (e.g., planning, development, testing).some text
    1. Start integrating Threat Modeling in the initial planning phase to set security requirements and objectives.
    2. Perform Threat Modeling during design reviews to find potential threats early.
  2. Regularly revisit Threat Modeling findings as the project progresses and make any necessary adjustments.some text
    1. Include Threat Modeling sessions in each development sprint to continuously address new threats.
    2. Conduct Threat Modeling during testing phases to identify and mitigate vulnerabilities before release.
  3. Incorporate Threat Modeling into DevOps practices to automate and streamline security assessments.some text
    1. Integrate security checks and Threat Modeling into the CI/CD pipeline.
    2. Use automation tools to regularly scan for vulnerabilities and automatically generate Threat Modeling reports.

Stay Ahead of Potential Threats and Adapt to New Risks

Making Threat Modeling a regular part of your development process will make the integration of security into your SDLC so much easier. Having a proactive stance strengthens your security posture and helps your teams develop a culture where security is ingrained in every step of your development journey.

And regularly revisiting your threat models? It helps you catch new vulnerabilities early and respond to new threats quickly. Plus, continuously refining your security measures will help make sure that your applications remain robust and reliable over time.

If you don't know where to start, or you're lost on how to integrate Threat Modeling into your SDLC, then let us help you. With our team of experts and advanced tools, we45 helps you identify, evaluate, and mitigate security threats effectively every time. Our team is skilled at making the Threat Modeling process smoother and more efficient which will make integrating security seamlessly into your development workflow EASIER.