intermediate
Threat Model: Chat Application
Realtime messages, contacts, sessions and attachments.
UserLLMAgentToolDataDecisionHumanGuardrail
Assets
Private messageshighly-sensitive
Loss of private messages harms users and the system’s core promise.
User identityconfidential
Loss of user identity harms users and the system’s core promise.
Attachmentsconfidential
Loss of attachments harms users and the system’s core promise.
Actors and capabilities
| Actor | Trust | Starting capability |
|---|---|---|
| Anonymous visitor | untrusted | Can send arbitrary public requests. |
| Authenticated user | semi-trusted | Can exercise product APIs within an account or tenant. |
| Backend service | trusted | Can read and modify scoped production data. |
| Administrator | privileged | Can perform exceptional cross-user operations. |
Entry points & trust boundaries
Attack surface
public Public API and login
Rate-limit, parse and authenticate at the first boundary.
authenticated Product resources
Every object needs a resource-level authorization decision.
privileged Admin operations
Step-up, separate authorization and audit.
public Webhook
Verify exact provider, body freshness and event identity.
Boundary validation
Browser ┃ TRUST ┃ API
origin where relevant · session/token · shape and limits
API ┃ TRUST ┃ Backend
principal · action · resource authorization
Backend ┃ TRUST ┃ Database
restricted role · tenant scope
Threats
A message id is loaded without participant authorization.
IMPACT · Compromise of private messages.
PREVENT · Enforce the boundary-specific control. Limit the responsible identity.
DETECT · Record principal, action and resource.
A bearer session is reused from a different device.
IMPACT · Compromise of user identity.
PREVENT · Enforce the boundary-specific control. Limit the responsible identity.
DETECT · Record principal, action and resource.
A hostile file reaches a privileged parser.
IMPACT · Compromise of attachments.
PREVENT · Enforce the boundary-specific control. Limit the responsible identity.
DETECT · Record principal, action and resource.
Residual risk & unknowns
Residual risks
- • Privileged insiders and control-plane compromise remain high-impact.
- • Business abuse can use technically valid operations.
Explicitly out of scope
- • Physical facilities and provider-internal controls.