Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/fattain-naime/engineering-docs/security-threat-modelnpx skills add fattain-naime/engineering-docs --skill security-threat-modelgit clone --depth 1 https://github.com/fattain-naime/engineering-docsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/fattain-naime/engineering-docs/security-threat-model)<a href="https://agentmods.dev/skills/fattain-naime/engineering-docs/security-threat-model"><img src="https://agentmods.dev/badge/skills/fattain-naime/engineering-docs/security-threat-model.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00047 | $0.03255 |
| Opus 5 | $0.00023 | $0.01628 |
| Sonnet 5 | $0.00009 | $0.00651 |
| Haiku 4.5 | $0.00005 | $0.00326 |
Grade A, and why
security-threat-model scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 242 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Purpose
Produce a structured threat model that systematically identifies what can go wrong in a system from a security perspective, who would attack it, how they would do it, and what concrete controls prevent or mitigate each attack.
Security is not a feature to add at the end. A threat model performed before implementation costs hours. A security breach found after launch costs millions and destroys trust that took years to build.
Input
Works best with: The name of the system, feature, or integration being threat-modeled. Also valuable: An existing architecture document, data flow diagram, API design, or description of how data moves through the system.
Example invocation: Threat model our new webhook delivery system. Merchants register endpoint URLs. Our system sends signed HTTP POST requests with event payloads. Merchants verify signatures using a per-merchant secret. The system retries failed deliveries up to 3 times with exponential backoff.
Key Concepts
STRIDE Framework (Microsoft SDL)
The six threat categories that cover all known attack classes:
| Letter | Threat | Violates | Example |
|---|---|---|---|
| S | Spoofing | Authentication | Attacker impersonates a legitimate user or system |
| T | Tampering | Integrity | Attacker modifies data in transit or at rest |
| R | Repudiation | Non-repudiation | User denies performing an action with no audit trail to prove otherwise |
| I | Information Disclosure | Confidentiality | Sensitive data exposed to unauthorized parties |
| D | Denial of Service | Availability | System overwhelmed or crashed, denying service to legitimate users |
| E | Elevation of Privilege | Authorization | Attacker gains access beyond their granted permissions |
Trust Boundaries
Trust boundaries are the locations in a system where data crosses from one trust zone to another. Attackers target trust boundaries because that is where:
- Input validation is most often missing
- Authentication is most often weak
- Data is most often exposed in transit
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 242 lines · 47 tokens per session scan A 0682bfc13999
security-threat-model is a skill published in the GitHub repository fattain-naime/engineering-docs (4 stars, last pushed 18d ago), licensed MIT. It adds 47 tokens to every session and 3,255 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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