Cleanup stored XSS from environments table

db/migrate/20181108091549_cleanup_environments_external_url.rb

+# frozen_string_literal: true
+
+class CleanupEnvironmentsExternalUrl < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    update_column_in_batches(:environments, :external_url, nil) do |table, query|
+      query.where(table[:external_url].matches('javascript://%'))
+    end
+  end
+
+  def down
+  end
+end

spec/migrations/cleanup_environments_external_url_spec.rb

+require 'spec_helper'
+require Rails.root.join('db', 'migrate', '20181108091549_cleanup_environments_external_url.rb')
+
+describe CleanupEnvironmentsExternalUrl, :migration do
+  let(:environments)    { table(:environments) }
+  let(:invalid_entries) { environments.where(environments.arel_table[:external_url].matches('javascript://%')) }
+  let(:namespaces)      { table(:namespaces) }
+  let(:projects)        { table(:projects) }
+
+  before do
+    namespace = namespaces.create(name: 'foo', path: 'foo')
+    project = projects.create!(namespace_id: namespace.id)
+
+    environments.create!(id: 1, project_id: project.id, name: 'poisoned', slug: 'poisoned', external_url: 'javascript://alert("1")')
+  end
+
+  it 'clears every environment with a javascript external_url' do
+    expect do
+      subject.up
+    end.to change { invalid_entries.count }.from(1).to(0)
+  end
+
+  it 'do not removes environments' do
+    expect do
+      subject.up
+    end.not_to change { environments.count }
+  end
+end