bcquality/microsoft/knowledge/security/do-not-expose-sensitive-data-in-event-publishers.md
Jesper Schulz-Wedde 62dabf9a11 Co-locate AL samples next to their knowledge articles
The /samples/ top-level tree is replaced with sibling files in each
knowledge-layer folder. An article and its demonstrations now live
side-by-side:

  microsoft/knowledge/<domain>/<slug>.md
  microsoft/knowledge/<domain>/<slug>.good.al
  microsoft/knowledge/<domain>/<slug>.bad.al

Rationale:
- Proximity. An article and its paired samples are one unit; the
  filesystem now reflects that.
- Layer ownership. Samples inherit layer precedence for free -- a
  /custom/ fork can override an article and its samples atomically,
  which the shared /samples/ tree previously made awkward.
- Trivial migration path. Action-skill source globs
  (*/knowledge/<domain>/**/*.md) are unchanged; sample discovery is a
  sibling-filename lookup.

Changes:
- git mv of all 65 sample files from samples/<domain>/<slug>/{bad,good}.al
  to microsoft/knowledge/<domain>/<slug>.{bad,good}.al (history preserved).
- Update See-sample references in all 37 articles that ship samples.
- skills/read.md: replace the no-code-blocks bullet with a pointer to a
  new Sample files section that fully specifies the sibling convention,
  the kinds (good/bad + forward-compatible), multi-technology rules,
  demonstration-only status, and layer-precedence behaviour.
- skills/write.md: update the samples pointer to match.
- README.md: annotate the knowledge tree with the sample sibling shape.
- samples/README.md deleted; content lifted into skills/read.md.
- Both generators (C:\temp\gen_performance_knowledge.py,
  C:\temp\gen_security_knowledge.py) updated to emit at the new paths
  and to stop writing samples/README.md. Re-running them is idempotent
  against the committed layout.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-04-17 13:45:33 +02:00

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Markdown

---
bc-version: [26..28]
domain: security
keywords: [event, publisher, extensibility, var-parameter]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Do not expose sensitive data in event publishers
> **Seed article.** Converted from an existing security-review prompt to bootstrap the BCQuality security corpus. Domain stewards should expand, restructure, and refine as needed.
## Description
Events in AL are extensibility contracts. Every subscriber — third-party, internal, or installed after the fact — receives the full set of event parameters. Parameters that carry secrets, pre-authorization state, or variables the publisher relies on for access control effectively become public, and var-parameters can be mutated by a subscriber to alter publisher behaviour.
## Best Practice
Design event signatures to carry only the data a subscriber legitimately needs. Do not pass SecretText, credential material, or flags the publisher depends on for access control. If a subscriber needs to veto an action, model it as a separate OnBefore event whose Handled pattern is documented — not as a general-purpose var Boolean callers can flip.
See sample: `do-not-expose-sensitive-data-in-event-publishers.good.al`.
## Anti Pattern
An OnBeforeElevateAccess publisher that exposes `var CanAccess: Boolean` — any subscriber installed on the tenant can flip it to true and escalate. Or a publisher that passes a SecretText parameter it obtained internally, handing it to every subscriber.
See sample: `do-not-expose-sensitive-data-in-event-publishers.bad.al`.