Trust boundary - The trust zone change element
Trust boundary box
Trust boundary line
The trust boundary element is represented by dotted lines or squares. Trust boundaries are used to describe data flow as it crosses different trust zone levels.
Examples include:
- Firewalls
- Connections to third-party services
- Parts of your system only available to administrators
Areas with changing trust zones are the most targeted by attackers, and should be carefully designed.
Microsoft has predefined trust-zone requirements for engineers to use internally. It takes the guesswork out of which boundaries to apply. If you work at Microsoft, contact your security team to learn more.
When to use the trust boundary element
Here are a few important points to remember about trust boundaries:
- Include trust boundaries to handle data flow as it crosses different trust zones.
- Trust boundary lines represent data flow as it crosses large environments, like the internet.
- Trust boundary boxes represent smaller environments, like sandbox environments and corporate networks.
Include context
Include the following context with each trust boundary element:
| Context | Questions |
|---|---|
| Description | Is it a corporate network boundary? Internet? Azure subscription? |