questionnaire.md

Security and Privacy Questionnaire for Captured Surface Control

Questions to Consider

2.1. What information might this feature expose to Web sites or other parties, and for what purposes is that exposure necessary?

Given a Web application WA that has used pre-existing means (getDisplayMedia()) to capture a tab T, and that therefore has access to all of T's pixels, this feature exposes to WA:

1. T's zoom-level. (This is exposed without another permission policy or prompt).
2. Potentially, additional pixels in T, if the user grants permission to forward gestures from WA to T, and/or allow WA to change T's zoom-level.

2.2. Do features in your specification expose the minimum amount of information necessary to enable their intended uses?

Yes.

2.3. How do the features in your specification deal with personal information, personally-identifiable information (PII), or information derived from them?

Not applicable.

2.4. How do the features in your specification deal with sensitive information?

Not applicable.

2.5. Do the features in your specification introduce new state for an origin that persists across browsing sessions?

Yes - the state of the permission policy introduced by this spec, "captured-surface-control".
Otherwise - no.

2.6. Do the features in your specification expose information about the underlying platform to origins?

The answer is probably "no", but it's worth mentioning that getSupportedZoomLevels() exposes the supported zoom-levels on the platform. User agents are encouraged to ensure the result is not dependent on the OS or the user's configuration of the user agent; that is, for a given browser version, the result should be the same for all users on any machine.

2.7. Does this specification allow an origin to send data to the underlying platform?

The answer is "no", but it's worth mentioning that setZoomLevel() allows applications to request that the user agent change zoom levels on specific tabs.

2.8. Do features in this specification enable access to device sensors?

No.

2.9. Do features in this specification enable new script execution/loading mechanisms?

No.

2.10. Do features in this specification allow an origin to access other devices?

No.

2.11. Do features in this specification allow an origin some measure of control over a user agent’s native UI?

Yes, in a limited way - the zoom-level of captured tabs can be changed. Naturally, this is reflected in the user agent's native UX that informs the user of a tab's zoom-level. This is limited so it only happens in response to direct interaction by the user with the capturing Web application.

2.12 What temporary identifiers do the features in this specification create or expose to the web?

None.

2.13. How does this specification distinguish between behavior in first-party and third-party contexts?

This feature does not distinguish first-party and third-party contexts.

2.14. How do the features in this specification work in the context of a browser’s Private Browsing or Incognito mode?

Not applicable.

2.15. Does this specification have both "Security Considerations" and "Privacy Considerations" sections?

Yes.

2.16. Do features in your specification enable origins to downgrade default security protections?

No.

2.17. How does your feature handle non-"fully active" documents?

This feature only works for documents which use pre-existing mechanisms to initiate tab-capture. A non-"fully active" document will have this capture-session interrupted, thereby also terminating the use of this feature.

2.18. What should this questionnaire have asked?

N/A