ATASM

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Architectures, Threats, Attack Surfaces, and Mitigations (ATASM) is an overarching framework to threat modeling.

• other models are often used with this, such as STRIDE and DREAD

Components

• Architecture
  • Understand the logical and component architecture of the system
  • Understand every communication flow and any valuable data that is moved and stored
• Threats
  • List all the possible threat agents for this type of system
  • List the ultimate goals of each of these threat agents
  • List the typical attack methods of the threat agents
  • List the System level objectives of threat agents using their attack methods
• Attack Surfaces
  • Decompose (factor) the architecture to a level that exposes every possible attack surface
  • Apply attack methods for expected objectives to the attack surfaces
  • Filter out threat agents who have no attack surfaces exposed to their typical methods
• Mitigations
  • List all existing security controls for each attack surface
  • Filter out all attack surfaces for which there is sufficient existing protection
  • Apply new security controls to the set of attack services for which there isn’t sufficient mitigation
  • Build a defense-in-depth¹

Process

1. Seek to understand the architecture
2. List all threat agents, goals, methods, and objectives
3. Analyze architecture’s attack surfaces
   • look at how attack methods and objectives would interact with the attack surface
4. Review security controls and attack surfaces
   • remove any attack surface that are sufficiently secured by existing controls
5. Remaining list is secured using new controls
   • focus on defense in depth

Footnotes

1. Brook schoenfield’s threat modeling methods | brookschoenfield.com. (n.d.). Retrieved April 17, 2026, from https://brookschoenfield.com/?page_id=341 ↩