Data Security

Threat Modeling for Robust Cybersecurity

February 23, 2024

Introduction

Threat modeling is a systematic approach to identifying and assessing potential security threats to a software system or organization. It allows organizations to proactively improve their security posture by discovering vulnerabilities and addressing them before attackers can exploit them. As cyber threats grow more sophisticated, threat modeling has become an essential practice for building robust cyber defenses.

What is Threat Modeling?

Threat modeling is the process of thinking like an attacker to identify what they want to accomplish and how they might try to accomplish it. The key steps in threat modeling are:

Identify assets – Inventory software, infrastructure, data, and other assets that may be targeted.
Define threats – Brainstorm potential threats like malware, data theft, denial of service, etc.
Map attack surface – Document the entry and exit points where attacks can be initiated.
Identify vulnerabilities – Analyze the design to find security flaws that may be exploited.
Rank threats – Prioritize threats based on likelihood and potential impact.
Mitigate risks – Develop strategies like input validation, encryption, monitoring, etc. to address vulnerabilities.

The goal is to systematically evaluate a system’s attack surface and take proactive measures to prevent, detect, and respond to threats.

Why is Threat Modeling Important?

Here are some key reasons why threat modeling is a critical cybersecurity technique:

Find unknown threats – Experienced attackers will often find creative ways to breach defenses. Threat modeling surfaces less obvious threats.
Prioritize risks – With limited resources, organizations must focus on fixing the most urgent vulnerabilities first.
Save costs – It is exponentially cheaper to address security in the design phase rather than after systems are built and deployed.
Meet compliance – Regulations often mandate that organizations demonstrate due diligence in securing systems and data.
Adopt security mindset – Threat modeling gets organizations proactively thinking about security.

When Should You Perform Threat Modeling?

Threat modeling provides the most value when performed continuously throughout the software development life cycle (SDLC):

Requirements gathering – Consider security goals and risks during initial planning.
Design phase – Analyze architecture and design before implementation.
Pre-release – Double check for new threats before launch.
Post-release – Revisit as code changes to address emerging threats.
System changes – Evaluate security impact of all upgrades and feature additions.

The earlier in the life cycle threats are identified, the easier and cheaper they are to address.

Threat Modeling Methodologies

There are several structured methodologies and frameworks available for guiding the threat modeling process:

STRIDE

STRIDE is a model developed by Microsoft focused on common threat categories:

Spoofing – Impersonating something or someone
Tampering – Modifying data or code
Repudiation – Denying actions
Information Disclosure – Exposing private data
Denial of Service – Disrupting service
Elevation of Privilege – Gaining unauthorized access

STRIDE provides a mnemonic for prompted thinking around different threat vectors.

PASTA

PASTA is an approach centered on seven practical steps:

Process – Define objectives, scope, and assumptions.
Architecture – Document detailed system design and workflows.
Static Analysis – Examine code, configurations, and infrastructure.
Threats – Brainstorm potential threat scenarios.
Attack Trees – Map out methods attacks could be carried out.
Attack Libraries – Research known attack patterns.
Analysis – Prioritize mitigations based on risks.

PASTA brings detailed structure to threat discovery, mapping, and response planning.

VAST

VAST focuses analysis on four core elements:

Values – Identify business assets and priorities to protect.
Access – Determine potential access points, both authorized and unauthorized.
Software – Evaluate app source code, configurations, and dependencies.
Threats – Research relevant threat sources, motivations and methods.

VAST keeps threat modeling centered on protecting what is most important.

Performing Threat Modeling

Conducting an effective threat modeling exercise involves three key phases:

Scope and Plan

Define scope – Specify what people, places, systems and data will be evaluated.
Set goals – State desired security posture and acceptable risk thresholds.
Assemble team – Include developers, security experts, product owners and risk managers.
Choose methodology – Select a framework like STRIDE or VAST to follow.

Analyze and Document

Decompose application – Break down software into elements like entry points, data flows, etc.
Identify assets – Catalog target assets, security domains, trust levels and vulnerabilities.
Map external dependencies – Document connections to external systems and third party code.
Define threat scenarios – Brainstorm potential attack goals, resources and methods.

Rank and Report

Prioritize threats – Rank based on severity of impact and likelihood of occurrence.
Develop mitigation plan – Detail remediation actions with owners and timelines.
Create visual threat model – Illustrate model diagrams, data flows, risk heat maps, etc.
Prepare report – Document findings, assumptions, methodologies and recommendations.

Integrating Threat Modeling

To make threat modeling most effective, organizations should:

Train security champions – Build internal expertise to lead threat modeling workshops.
Include in SDLC – Incorporate threat modeling into development processes and design reviews.
Use automated tools – Leverage software to help map systems, surface issues, and generate reports.
Re-test and audit – Continuously validate controls and repeat modeling on evolving systems.
Tie to compliance – Align with security frameworks and monitor compliance.

Conclusion

Threat modeling brings a proactive, offensive mindset to securing systems and data. By analyzing attack scenarios early, organizations can develop layered defenses to stop attackers in their tracks. To build robust cybersecurity, everyone from executives to developers must make threat modeling a priority across the entire software lifecycle.