--- a/.cron.yml
+++ b/.cron.yml
@@ -48,8 +48,30 @@ jobs:
     - name: nightly-win64
       job:
           type: decision-task
           treeherder-symbol: Nd-win64
           target-tasks-method: nightly_win64
       run-on-projects:
           - comm-central
       when: []  # never (hook only)
+
+    - name: periodic-update
+      job:
+          type: decision-task
+          treeherder-symbol: Nfile
+          target-tasks-method: file_update
+      run-on-projects:
+          - comm-central
+          - comm-beta
+          - comm-esr60
+      when:
+          by-project:
+              # No default branch
+              comm-central:
+                  - {weekday: 'Monday', hour: 10, minute: 0}
+                  - {weekday: 'Thursday', hour: 10, minute: 0}
+              comm-beta:
+                  - {weekday: 'Monday', hour: 10, minute: 0}
+                  - {weekday: 'Thursday', hour: 10, minute: 0}
+              comm-esr60:
+                  - {weekday: 'Monday', hour: 10, minute: 0}
+                  - {weekday: 'Thursday', hour: 10, minute: 0}

new file mode 100644
--- /dev/null
+++ b/taskcluster/ci/repo-update/kind.yml
@@ -0,0 +1,48 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+loader: taskgraph.loader.transform:loader
+
+transforms:
+   - taskgraph.transforms.repo_update:transforms
+   - taskgraph.transforms.task:transforms
+
+
+job-defaults:
+   worker:
+      env:
+         DO_BLOCKLIST:
+            by-project:
+               comm-central: "1"
+               comm-esr60: "1"
+               comm-beta: "1"
+               default: ""
+         USE_MOZILLA_CENTRAL: ""
+
+
+jobs:
+   blocklist-update:
+      name: periodic_file_update
+      description: Blocklist update
+      run-on-projects: []  # Only run via cron
+      treeherder:
+         kind: build
+         platform: linux64/opt
+         symbol: pfu
+         tier: 1
+      worker-type: aws-provisioner-v1/gecko-{level}-b-linux
+      worker:
+         implementation: docker-worker
+         os: linux
+         docker-image: {in-tree: periodic-updates}
+         max-run-time: 3600  # Takes < 1 minute
+         env:
+            PRODUCT: thunderbird
+            REVIEWERS: "rjl"
+         command:
+            - /runme.sh
+         taskcluster-proxy: true
+
+      scopes:
+         - secrets:get:project/comm/thunderbird/releng/build/level-{level}/arc-phabricator-token