bcquality/microsoft/knowledge/web-services/api-page-least-privilege-write-access.md
Michael Dieringer 0120b874b2 Address Jesper Schulz-Wedde's review on PR #157
- release-must-update-app-version.md: reframe around AppSource's actual
  strict full-version-ordering requirement; scope branching-policy
  claims as team convention, not platform rule.
- pictures-must-use-media-not-blob.md: MediaSet is a collection of
  independent media objects, not automatic image variants/thumbnails.
- log-writes-must-survive-rollback.{md,good.al}: StartSession's only
  data channel into the new session is its Record parameter to a
  TableNo-scoped codeunit; a setter called on a local instance before
  starting the session populates nothing in the new session.
- exposed-objects-must-be-in-a-permission-set.md: correct the three
  exposure mechanisms (Web Services config, PageType/QueryType=API,
  ServiceEnabled as a method-only attribute).
- pages-must-not-contain-business-logic.md: scope to persisted
  mutations and cross-entry-point rules; presentation-only
  calculations and table-owned invariants are not violations.
- given-blocks-must-cover-full-precondition-chain.good.al: replace
  invented LibrarySales calls with the real API
  (CreateCustomer/CreateSalesOrderForCustomerNo/PostSalesDocument).
- test-feature-scenario-tags.{md,good.al}: move [SCENARIO] inside the
  test procedure body to match the current BCApps corpus; keep
  [FEATURE] at codeunit level per Microsoft's own documented option.
- ui-test-codeunit-naming.md: scope the _UT suffix and adjacent-ID
  pairing as an explicit team convention, not a BCApps-wide standard.
- page-design-must-match-bc-page-type-conventions.md /
  table-design-must-match-bc-table-type-conventions.md: Card's
  single-key primary-key claim is a contextual heuristic, not a
  mandatory constraint (Ship-to Address, Customer/Vendor Bank Account
  are real composite-key Card pages); a Subsidiary table with its own
  identity commonly gets List+Card, not Worksheet/Tabular.
- api-page-least-privilege-write-access.{md,good.al}: only page-placed
  fields are ever exposed; set InsertAllowed/DeleteAllowed=false in the
  good sample so a narrow field set can't still create/delete records.
- source-organized-by-feature-not-object-type.md,
  test-one-when-per-test.md: scope as team/testing-design conventions,
  not Microsoft platform requirements.
- upgrade-tag-logic-must-not-nest-deeply.md: add the Microsoft Learn
  citation that already backs the two-level nesting limit.
- Wire the new articles into the testing/data-modeling/error-handling/
  security/ui review skills' candidate-selection signals.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-09-21 22:43:16 +02:00

2 KiB

bc-version domain keywords technologies countries application-area
all
web-services
api-page
least-privilege
write-access
odata
security
external-api
identity-fields
al
w1
all

Give API pages least-privilege write access

Description

A general-purpose API page that exposes many fields should not be widened to allow writes on one additional field. A PageType = API page consumed by an external integration, an automation agent, or a partner system carries the same risk regardless of caller: a write-enabled page with no per-field restriction is a wide-open surface. Least privilege has to cover both dimensions of exposure: which fields are on the page, and which operations the page allows. Only a field actually placed on the page is reachable at all — but a page that includes many fields, with InsertAllowed/ModifyAllowed/DeleteAllowed left at their defaults and no Editable = false on most of them, leaves every one of those included fields — identity fields and financially significant ones among them — fully writable, with nothing marking that as deliberate. Restricting fields alone is not enough either: a page with only two fields on it can still let a caller insert brand-new records or delete existing ones if InsertAllowed/DeleteAllowed are left at their true defaults (both true).

Best Practice

Create a separate, minimal API page that exposes only the key and the specific field the consumer needs to write, with everything else Editable = false or simply absent from the page — and set InsertAllowed/DeleteAllowed to false unless the consumer's use case genuinely needs to create or delete records through that page.

See sample: api-page-least-privilege-write-access.good.al.

Anti Pattern

Widening an existing general-purpose API page with write access to one field, leaving every other field on the page (including identity and posting fields) writable by default because no one added Editable = false.

See sample: api-page-least-privilege-write-access.bad.al.