Threat Modeling Insider – June 2025

Threat Modeling Insider Newsletter

45th Edition – June 2025

Welcome!

Welcome to this month’s edition of Threat Modeling Insider! In our featured guest article, Securing AI Agents: A Framework to Maximize ROI, Minimize Risk, Michael Novack explores AI agent threats, relevant mitigations, and strategies to focus your security efforts.

Meanwhile, on the Toreon blog, Sebastien Deleersnyder presents STRIDE-AI, our enhanced methodology for comprehensive AI threat modeling, along with our new 3-day AI threat modeling training.

But that’s not everything, so let’s dive in!

Threat Modeling Insider edition

Welcome!

Welcome to this month’s edition of Threat Modeling Insider! In our featured guest article, Securing AI Agents: A Framework to Maximize ROI, Minimize Risk, Michael Novack explores AI agent threats, relevant mitigations, and strategies to focus your security efforts.

Meanwhile, on the Toreon blog, Sebastien Deleersnyder presents STRIDE-AI, our enhanced methodology for comprehensive AI threat modeling, along with our new 3-day AI threat modeling training.

But that’s not everything, so let’s dive in!

On this edition

Tips & tricks
Securing HTTP based APIs

Training update
An update on our training sessions.

Guest article

Securing AI Agents: A Framework to Maximize ROI, Minimize Risk

In the evolving landscape of cybersecurity, AI agents present both opportunities and unique challenges. It’s crucial to understand the gaps in your cybersecurity program to effectively protect these advanced systems. This presentation will explore AI agent threats, relevant mitigations, and strategies to focus your security efforts.

The threats are novel enough according to the Cloud Security Alliance they made a new threat modeling framework called MAESTRO just for AI agents. We discuss if this is really needed.

What are AI Agents?

AI agents are advanced systems that utilize artificial intelligence to perform actions or make decisions, often with some degree of autonomy. They are designed to perceive their environment, process information, and take actions to achieve specific goals.

Understanding AI Agent Threat Modeling

The perspectives on the threat landscape for AI agents vary widely. Some believe existing cybersecurity programs are sufficient, while others express alarm about the inadequacy of current controls in an AI-driven world.

Controls

To highlight this disparity we will compare the AI agent threat modeling framework MAESTRO from the Cloud Security Alliance to a modified version of STRIDE. 

We want to be clear that the point of this article is NOT to say MAESTRO is not needed. We acknowledge there are gaps with STRIDE which is why we have to modify it for an AI agent use case. We are using the widely-adopted STRIDE framework to illustrate how much of a gap MAESTRO is actually filling. Use what works best for your needs.

What is MAESTRO?

MAESTRO (Multi-Agentic System Threat Model) is a 7-layer reference architecture for agentic AI developed by the Cloud Security Alliance. This framework is designed to provide a structured approach to threat modeling for AI agents, addressing the limitations of traditional methods like STRIDE. 

Why Does MAESTRO Exist?

Current threat modeling frameworks, like STRIDE, are not well-suited for AI agents. STRIDE, while a good starting point, doesn’t fully address the unique challenges posed by AI agents, such as adversarial attacks and risks associated with unpredictable learning and decision-making. MAESTRO provides a more tailored approach to threat modeling in this context. 

Maestro

A Modified STRIDE + ML

To better understand the gaps that AI creates in a cybersecurity program, let’s modify STRIDE so it can handle the unique challenges of AI agents. This is done by incorporating two new threat categories “Misunderstanding” and “Lack of Accountability” (ML), which can be employed. 

  • Misunderstanding: This refers to models having undesirable assessments due to a lack of context or malicious intervention, leading to unexpected emerging behaviors.
  • Lack of Accountability: This occurs when actions are performed without clear governance or ownership, making it difficult to determine responsibility when issues arise.

Applying STRIDE + ML to AI Agents

Frameworks such as the OWASP Multi Agentic Threat Modeling Guide and the Cloud Security Alliance Agentic Threat Modeling Guide can be mapped into STRIDE + ML to provide a clearer view of AI agent threats. This mapping reveals that a significant portion of AI agent threats can be categorized using traditional STRIDE, but a notable percentage require the additional ML categories. 

STRIDE

AI Agent Threats and Mitigations

AI agent threats can be categorized, and mitigations can be mapped to these categories. Some threats can be mitigated using existing cybersecurity measures, while others require extending capabilities or implementing new mitigations. 

We use the OWASP AI Agent threat taxonomy as it is more concise compared to the Cloud Security Alliance taxonomy. Almost all of the threats in the Cloud Security Alliance threat taxonomy can be categorized into the OWASP taxonomy.

Existing Mitigations
  • Threats with Existing Mitigations:
    • Spoofing (T9 – Identity Spoofing)
    • Repudiation (T8 – Repudiation and Untraceability)
    • Information Disclosure (T12 – Agent Communication Poisoning)
    • Denial of Service (T4 – Resource Overload)
    • Elevation of Privilege (T3 – Privilege Compromise)
  • Threats Requiring Expanded Mitigations: This category includes
    • Spoofing (T13 – Rogue Agents)
    • Tampering (T11 – Unexpected RCE and Code Attacks, T1 – Memory Poisoning)
    • Denial of Service (T10 – Overwhelming HITL)
    • Elevation of Privilege (T14 – Human attacks on MAS)
  • Threats Requiring New Mitigations: These are unique to AI agents
    • Misunderstanding (T2 – Tool Misuse, T5 – Cascading Hallucinations, T6 – Intent Breaking & Goal Manipulation)
    • Lack of Accountability (T7 – Misaligned & Deceptive Behaviour, T15 – Human Trust Manipulation)

Mitigation Options and AI-Specific Considerations

The cloud security alliance provides a good list of mitigations to focus on. Many of the mitigations should be part of any robust cybersecurity program regardless if AI is used or not. Below are the additional mitigations required specifically for AI systems.

Mitigation Description Example
Review internal governance and control frameworks Train agents to be robust against adversarial examples. During the model training process add in an example of prompts trying to get toxic responses about ageism. These should be labeled so the model knows that this type of prompt should not be answered.
Formal Verification Use formal methods to verify agent behavior and ensure goal alignment. Given the intent of an agent is only to provide information and analysis about a customer's bank account. Regularly audit that an agent is not attempting to do unexpected activity like transfer funds.
Explainable AI (XAI) Improve transparency in agent decision-making to facilitate auditing. Be able to explain why an insurance claim agent denied a specific customer's claim.
Red Teaming Simulate attacks to identify vulnerabilities. Researching the latest prompt injection techniques and seeing if they are successful or not on your system.
Safety Monitoring Implement runtime monitoring to detect unsafe agent behaviors. With a platform independent of the agent, verifying incoming prompts are not attempts of jailbreaking or trying to get the agent to do unethical actions like illegal or discriminatory behavior.

Focusing Your Efforts

The AI agent space is not as unique as many portray it to be, but we also cannot pretend that our existing cybersecurity control strategy is sufficient.

To effectively improve the ROI of your AI agent security efforts, focus on:

  • First look at your current capabilities to see how you can address ~⅔ of the AI threat space.
  • Look at the market for the emergent ~⅓ of AI threats, as these mitigations are being built now, so unlikely to exist with your current capabilities.

By understanding the nuances of AI agent threats and applying targeted mitigations, organizations can better protect these systems and maximize their return on investment in AI technologies.

CSA threats related to OWASP threats

The table below is a mapping of the threats defined in the OWASP AI Agent Threat and Mitigation Guide to the threats in the Cloud Security Alliance MAESTRO documentation. As most of the analysis of this blog is done using the OWASP threat taxonomy, I wanted to make sure you see how it relates to the CSA documentation, as it is the source of the MAESTRO threat modeling framework, and OWASP Mult-Agent Threat Modeling Guide references the CSA documentation.

OWASP AI Agent Mitigation Guide tries to only call out threats that are unique to AI Agents. (Section Reference Threat Model in OWASP AI Agent Threat and Mitigation Guide). It builds upon the existing OWASP documentation to reduce redundancy. Some of the CSA threats correspond to threats called out in other OWASP documentation.

STRIDE + ML OWASP CSA
Spoofing T9 – Identity Spoofing Agent Impersonation
T13 – Rogue Agents Compromised Security AI Agents
Compromised Agents
Tampering T1 – Memory Poisoning Data Poisoning
Data Tampering
Security Agent Data Poisoning
T11 - Unexpected RCE and Code Attacks Input Validation Attacks
LLM03:2025 Supply Chain
A06:2021-Vulnerable and Outdated Components
API9:2023 - Improper Inventory Management
Supply Chain Attacks
Compromised Framework Components
Compromised Observability Tools
Marketplace Manipulation
Integration Risks
Compromised Agent Registry
Malicious Agent Discovery
Agent Pricing Model Manipulation
A08:2021-Software and Data Integrity Failures Compromised Container Images
Infrastructure-as-Code (IaC) Manipulation
Compromised RAG Pipelines
Manipulation of Evaluation Metrics
Poisoning Observability Data
Repudiation T8 – Repudiation and Untraceability Repudiation
Information
Disclosure
T12 – Agent Communication Poisoning Not called out as a unique threat, but in mitigations
Secure Inter-Layer Communication
LLM02:2025 Sensitive Information Disclosure Data Leakage
Data Exfiltration
Data Leakage through Observability
Model Stealing
Model Inversion/Extraction
Model Extraction of AI Security Agents
Membership Inference Attacks
Denial of Service T4 – Resource Overload Denial of Service on Data Infrastructure
Denial of Service on Framework APIs
Denial of Service (DoS) Attacks
Resource Hijacking
Denial of Service on Evaluation Infrastructure
T10 – Overwhelming HITL No clear equivalent in CSA
Elevation of Privilege T3 – Privilege Compromise Lateral Movement
Privilege Escalation
Backdoor Attacks
Orchestration Attacks
Agent Identity Attack
T14 – Human attacks on MAS No clear equivalent in CSA
Misunderstanding T2 – Tool Misuse Agent Tool Misuse
Inaccurate Agent Capability Description
T5 - Cascading Hallucinations Goal Misalignment Cascades
Horizontal/Vertical Solution Vulnerabilities
T6 – Intent Breaking & Goal Manipulation Agent Goal Manipulation
T7 – Misaligned & Deceptive Behaviour Reprogramming Attacks
Adversarial Examples
Framework Evasion
Evasion of Detection
Evasion of Security AI Agents
Lack of Accountability T15 – Human Trust Manipulation Regulatory Non-Compliance by AI Security Agents
Bias in Security AI Agents
Lack of Explainability in Security AI Agents

OWASP threats justification for each STRIDE + ML category

STRIDE + ML OWASP Justification
Spoofing T9 – Identity Spoofing Attackers exploiting authentication mechanisms to impersonate AI agents or human users. By assuming a false identity, the attacker can then execute unauthorized actions under that guise.
T13 – Rogue Agents An attacker might leverage identity spoofing techniques to impersonate a legitimate AI agent. By successfully authenticating as an existing agent or creating a new agent that masquerades as legitimate, the attacker can introduce a "rogue" agent into the system under a false identity. This rogue agent can then carry out malicious activities.
Tampering T1 – Memory Poisoning An attacker injecting malicious data or code into the memory space of an AI agent or the underlying system. This directly constitutes unauthorized modification, which is the core of the Tampering threat category.
T11 - Unexpected RCE and Code Attacks The ultimate aim of an attacker exploiting an RCE vulnerability is to tamper with the system's intended state and behavior. By injecting and executing their own code, they are directly modifying how the AI agent operates, the data it processes, or the system it runs on.
Repudiation T8 – Repudiation and Untraceability This category deals with the ability of an attacker (or even a legitimate user) to deny having performed an action or transaction. Untraceability directly supports repudiation by making it difficult or impossible to link an action back to a specific individual or entity.
Information
Disclosure
T12 – Agent Communication Poisoning This category deals with the threat of an attacker gaining unauthorized access to sensitive information and potentially altering. You could make the case for this to be in Tampering as well. If communication between AI agents is not properly secured, an attacker eavesdropping on the network can gain valuable insights.
Denial of Service T4 – Resource Overload This category focuses on attacks that aim to make a system or service unavailable to legitimate users or processes. Resource overload, by its very nature, achieves this by consuming excessive system resources (CPU, memory, network bandwidth, storage) to the point where the AI agent or the underlying system can no longer function correctly or respond to legitimate requests.
T10 – Overwhelming HITL The core of "Overwhelming HITL" is to flood the human operator with an excessive number of requests, alerts, or decisions, rendering them unable to effectively process and respond in a timely manner. This effectively makes the HITL component unavailable or significantly degrades its performance, leading to a denial of the intended service or oversight.
Elevation of Privilege T3 – Privilege Compromise This category focuses on the threat of an attacker gaining higher levels of access or permissions than they were originally intended to have. Privilege compromise is precisely the act of an attacker successfully obtaining these elevated privileges within the AI agent system or its underlying infrastructure.
T14 – Human attacks on MAS In many scenarios, human attackers might not be exploiting technical vulnerabilities to gain new privileges. Instead, they might be leveraging their existing authorized access and the inherent trust the system places in human operators to perform actions that go beyond the expected or safe scope of their intended use.
Misunderstanding T2 – Tool Misuse An AI agent or user lacks sufficient context about a tool's function or is misled by malicious input, leading to a flawed assessment of its proper application. This flawed assessment results in the tool being used in unintended ways, causing unexpected and undesirable emerging behaviors in the AI system due to this fundamental misunderstanding of the tool's role or implications.
T5 - Cascading Hallucinations An initial lack of context or a maliciously introduced falsehood leads an AI model to make an incorrect assessment, which then compounds in subsequent reasoning steps, generating further inaccurate outputs and unexpected behaviors. Each hallucination builds upon a prior flawed assessment, demonstrating a cascading "Misunderstanding" of the underlying information or task.
T6 – Intent Breaking & Goal Manipulation A model's assessment of the user's intended goal is incorrect due to a lack of proper context or malicious prompting designed to mislead it. This "Misunderstanding" of the desired outcome results in the model exhibiting unexpected behaviors that deviate from or actively subvert the user's actual objective.
Lack of Accountability T7 – Misaligned & Deceptive Behaviour A model's assessment of appropriate action is flawed due to insufficient context regarding ethical guidelines or malicious prompting that manipulates its understanding of desirable behavior. This "Lack of Accountability" leads to unexpected emerging behaviors that are either not aligned with intended values or actively deceptive.
T15 – Human Trust ManipulationS When a model's output, influenced by insufficient context or malicious prompting, leads a human to form an inaccurate assessment of the model's reliability or the situation it presents. This "Lack of Accountability" of the model's trustworthiness can result in unexpected and potentially harmful human behaviors based on that flawed assessment.

OWASP justify level of mitigations in the industry justification

Mitigation Availability OWASP Threat Justification
Existing T9 – Identity Spoofing Standard Identity Access Management (IAM) should be used
T8 - Repudiation and Untraceability Standard logging methods will suffice.
T12 - Agent Communication Poising There are established protocols to perform secure communication. If using new protocols they should have similar levels of cryptographic and authentication capabilities.
T4 - Resource Overload There are robust mechanisms to throttle rate limits on a frequency and payload level. This just needs to be applied to APIs that utilize LLM capabilities.
T3 - Privilege CompromiseThis calls out standard least privilege controls with strong authN/authZ systems and only granting the permission that is needed.
Expand T13-Rougue Agents We have ways to detect if infrastructure has been compromised. Now the activities a rogue agent would perform are more subtle, so these detection mechanisms should be improved.
T11 - Unexpected RCE and Code Attacks Your infrastructure should already be limited to not execute arbitrary code. There are also some detection mechanisms for detecting and understanding code, but these capabilities will need to get better to comfortably full allow agents to generate and utilize code on the fly.
T1 - Memory Poisoning The core mitigations are:
- Session management to separate users memory and regularly clearing.
- This in the expand category as normally memory management is more about performance than security.
T10 - Overwhelming HITL We do have ways to mitigate DDoS attacks, but these are normally in the context of protecting technology workloads not people. That being said we can adopt some of those principles when routing traffic to people to resolve.
T14 - Human attacks on MASApply a zero-trust mentality between agents. All actions should be fully validated if authorized and appropriate when communication between agents happen. As it might be hard to know what are valid actions we can apply a zero-trust mentality to get part of the way there.
New T2 - Tool Misuse The ecosystem of tools are actively evolving and the industry standards are being established. Things like MCP auto-discovery of tools is a new type of 3rd party risk. In theory an agent could use a new tool without anyone's knowledge. This a level of dynamic 3rd party management the industry has not done before.
T5 - Cascading Hallucionations It will be hard to validate what is appropriate behavior for the agent as the potential scope output is too large. A new way of output validation and monitoring will be needed.
T6 - Intent Breaking & Goal Manipulationg It will be hard to validate what is appropriate behavior for the agent as the potential scope output is too large. A new way of output validation and monitoring will be needed.
T7 - Misaligned & Deceptive Behavior It will be hard to validate what is appropriate behavior for the agent as the potential scope output is too large. A new way of output validation and monitoring will be needed.
T15 - Human Trust ManipulationIt will be hard to validate what is appropriate behavior for the agent as the potential scope output is too large. A new way of output validation and monitoring will be needed.

CURATED CONTENT

Handpicked for you

Toreon Blog: Mind the Gap: STRIDE-AI

Threat Modeling as Code: Implementing STRIDE in DevSecOps

The security landscape is changing rapidly as AI integrates into every part of our lives – from smart assistants and recommendation systems to autonomous vehicles and vision technology. While traditional cybersecurity practices remain essential, AI-enabled systems introduce new types of threats that require a specialized approach. At Toreon, we’ve experienced this firsthand. That’s why we’re excited to launch STRIDE-AI, our enhanced methodology for comprehensive AI threat modeling, along with our new 3-day AI threat modeling training.

In the DevSecOps era, security is built into the development lifecycle, not bolted on after the fact. While traditional methods can slow delivery, Threat Modeling as Code (TMAC) enables automated, scalable, and continuous security assessments.

This article explores how to implement STRIDE, a Microsoft-developed threat classification framework, within DevSecOps. Learn how to automate threat modeling, integrate it into your CI/CD pipelines, and catch vulnerabilities early, before they reach production.

Threat Modeling Guide for Software Teams

Threat modeling helps teams understand how data moves through systems and spot risks that automated tools often miss. Instead of treating it as a one-time or standalone activity, teams should embed threat modeling into their development workflow through small, ongoing efforts. This article offers practical ways to get started, whether you’re focused on application development, infrastructure, or both. With rising cybersecurity threats and growing accountability, making threat modeling a regular habit is more important than ever.

TIPS & TRICKS

Securing HTTP-based APIs

This UK NCSC guidance offers practical advice for securing HTTP-based APIs and is intended for technical teams involved in designing or building applications with API endpoints. Keep in mind that full security depends on performing threat modelling tailored to your specific architecture and use cases.

Our Black Hat "Whiteboard Hacking" (hands-on threat modeling) training is going virtual!

While we’ll miss the in-person experience, this opens up the opportunity for more participants worldwide who might not be able to travel to Las Vegas.
Our training stands out due to its hands-on nature, small group work, collaboration, and exercises based on real-world situations.

This year, we’re covering hot topics including:

  • AI threat modeling, with exercises related to chatbots
  • Cloud, including storage and CI/CD pipelines
  • IoT, embedded devices, and systems

Robert Hurlbut will be delivering the training, so we’re looking forward to seeing you there!

Our trainings & events for 2025

Book a seat in our upcoming trainings & events

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, virtual, hosted by Black Hat USA, Las Vegas 

2-5 August 2025

Threat Modeling Practitioner training, hybrid online, hosted by DPI 

Cohort starting on 18 August 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, in-person, Blue Team Con, Chicago, USA

4-5 September 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, virtual, hosted by Black Hat USA, Las Vegas 

2-5 August 2025

Threat Modeling Practitioner training, hybrid online, hosted by DPI 

Cohort starting on 18 August 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, in-person, Blue Team Con, Chicago, USA

4-5 September 2025

Hands-on Threat Modeling AI, in-person, hosted by BruCON, Belgium

22-24 September 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, in-person, OWASP Global AppSec, Washington DC

4-5 November 2025

Threat Modeling Practitioner training, hybrid online, hosted by DPI 

Cohort starting on 1 December 2025

Hands-on Threat Modeling AI, in-person, hosted by BruCON, Belgium

22-24 September 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, in-person, OWASP Global AppSec, Washington DC

4-5 November 2025

Threat Modeling Practitioner training, hybrid online, hosted by DPI 

Cohort starting on 1 December 2025

Advanced Whiteboard Hacking a.k.a. Hands-on Threat Modeling, in-person, NDC Security Manchester, UK

1-2 December 2025

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