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PATTERN Cited by 1 source

Static allowlist for critical rules

When an enforcement tool pulls its ruleset from a central sync server, there's a dependency chain: network → sync server → complete ruleset delivery → local enforcement. Break any link and the enforcer is either lying (missing allow rules → valid binaries blocked) or silent (no rules at all → fail-open or fail-closed depending on config).

Static allowlist for critical rules breaks the dependency for the handful of rules that must never fail-closed: pin them in the local configuration shipped with the enforcer's install image, so they're valid regardless of sync-server state.

Shape

  • Identify the minimum set of must-run binaries — typically MDM client (the only way to fix a broken device remotely), browser (gateway to support docs / self-service portals), chat client (how the user gets help), VPN client (if that's how users reach the corporate network).
  • Hard-code those rules in the enforcer's local config — this is config that ships with the agent install, managed by the MDM deploy pipeline, not distributed by the sync server.
  • Keep the list very short — every static rule is a rule that skips the normal review workflow. Static ≠ "all rules that seem important"; static = "rules whose failure would prevent us from ever fixing this machine remotely".
  • Audit when changed — static-rule updates flow with the agent release, which goes through the full software-release pipeline (code review, signed builds, staged rollout), not the rule-change pipeline.

Why this matters specifically

With small rulesets (hundreds of entries), rule sync is sub-second and rarely fails. The pattern matters when the ruleset grows enough that initial sync on a new device takes long enough to occasionally fail mid-delivery:

  • User gets a brand new laptop.
  • MDM installs the enforcer agent.
  • Agent attempts first full sync.
  • Connection drops mid-sync; agent has partial ruleset.
  • Critical apps (MDM itself, Chrome, Slack) aren't in the partial set.
  • User boots to a locked-down machine they can't communicate through to ask for help.

The static allowlist is the minimum set needed to get the user back to a state where they can receive help and the agent can complete its sync.

Why this isn't cheating

  • Static rules are a bounded surface (a dozen rules, all for apps users would install anyway). The sync-server path handles the other 79,000+ rules.
  • The release pipeline for agent config is not the rule-change pipeline — static rules go through strict code-review + package-signing, while sync-server rules go through the day-to-day rule-edit workflow. Trust levels are different on purpose.
  • Without this pattern the team has a sync-at-install-time single-point-of-failure baked into their rollout strategy.

Cost

  • Any change to static rules requires an agent re-release, so they can't churn.
  • The set of apps in the static allowlist is effectively a "cannot be killed by security" list — which means those apps' supply chains need appropriate vetting.

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