th: deal with "that one spammer"

app/services/activitypub/process_account_service.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'digest'
+
 class ActivityPub::ProcessAccountService < BaseService
   include JsonLdHelper
   include DomainControlHelper
@@ -87,6 +89,9 @@ class ActivityPub::ProcessAccountService < BaseService
     set_immediate_protocol_attributes!
     set_fetchable_key! unless @account.suspended? && @account.suspension_origin_local?
     set_immediate_attributes! unless @account.suspended?
+
+    TreehouseAutomodExt.heuristic_auto_suspend!(@account)
+
     set_fetchable_attributes! unless @options[:only_key] || @account.suspended?
 
     @account.save_with_optional_media!
@@ -334,4 +339,88 @@ class ActivityPub::ProcessAccountService < BaseService
     emoji.image_remote_url = image_url
     emoji.save
   end
+
+  module TreehouseAutomodExt
+    HEURISTIC_AUTO_SUSPEND_ACTIVE = ENV.fetch('TH_HEURISTIC_AUTO_SUSPEND', '') == 'that-one-spammer'
+    AUTOMOD_ACCOUNT_USERNAME = ENV['TH_STAFF_ACCOUNT']
+
+    # hardcoded for now
+    # md5 because they don't deserve more mentions
+    HEURISTIC_NAMES = {
+      '0116a9deace3289b7092e945ef5ca0a5' => Set['57d3d0b932cc9cd01be6b2f4e82c1a4a']
+    }
+    # probably mathematically impossible to collide, but just in case...
+    HEURISTIC_MAX_LEN = 16
+
+    COMMENT_HEADER = <<~EOS
+    Tracking Report - automatically created by TreehouseAutomodExt
+    EOS
+
+    WARNING_TEXT = <<~EOS
+    Tracking Infraction - automatically created by TreehouseAutomodExt
+    EOS
+
+    EXPLANATION = <<~EOS
+    This account was automatically suspended by TreehouseAutomodExt, an unsupported feature of Treehouse Social.
+
+    Currently, the heuristic should only automatically suspends any accounts with one specific username and one of several display name variants.
+
+    If this action is unexpected, please unset TH_HEURISTIC_AUTO_SUSPEND.
+    EOS
+
+    def self.heuristic_auto_suspend?(account)
+      return false unless HEURISTIC_AUTO_SUSPEND_ACTIVE
+
+      return unless account.username.length < HEURISTIC_MAX_LEN && account.display_name.length < HEURISTIC_MAX_LEN
+
+      username_md5 = Digest::MD5.hexdigest(account.username)
+      display_name_md5 = Digest::MD5.hexdigest(account.display_name)
+
+      HEURISTIC_NAMES[username_md5].include?(display_name_md5)
+    end
+
+    def self.heuristic_auto_suspend!(account)
+      return unless heuristic_auto_suspend?(account)
+
+      file_tracking_report!(account) unless account.suspension_origin == :local
+
+      account.suspended_at = Time.now.utc unless account.suspension_origin == :local
+      account.suspension_origin = :local
+      account.save!
+    end
+
+    def self.file_tracking_report!(account)
+      reporter = staff_account
+      return unless reporter
+
+      report = ReportService.new.call(
+        reporter,
+        account,
+        {
+          comment: "#{COMMENT_HEADER}\n\n#{EXPLANATION}",
+          th_skip_notify_staff: true,
+          th_skip_forward: true,
+        }
+      )
+      report.spam!
+      report.assign_to_self!(reporter)
+
+
+      account_action = Admin::AccountAction.new(
+        type: 'suspend',
+        report_id: report.id,
+        target_account: account,
+        current_account: reporter,
+        send_email_notification: false,
+        text: WARNING_TEXT,
+      )
+      account_action.save!
+
+      report.resolve!(reporter)
+    end
+
+    def self.staff_account
+      Account.find_local(AUTOMOD_ACCOUNT_USERNAME) if AUTOMOD_ACCOUNT_USERNAME
+    end
+  end
 end

app/services/report_service.rb

@@ -36,6 +36,7 @@ class ReportService < BaseService
   end
 
   def notify_staff!
+    return if @options[:th_skip_notify_staff]
     return if @report.unresolved_siblings?
 
     User.those_who_can(:manage_reports).includes(:account).each do |u|
@@ -53,6 +54,7 @@ class ReportService < BaseService
   end
 
   def forward?
+    return false if @options[:th_skip_forward]
     !@target_account.local? && ActiveModel::Type::Boolean.new.cast(@options[:forward])
   end
 

spec/services/activitypub/process_account_service_spec.rb

@@ -205,4 +205,112 @@ RSpec.describe ActivityPub::ProcessAccountService, type: :service do
       expect { subject.call('user1', 'foo.test', payload) }.to change { Account.remote.count }.by_at_most(5)
     end
   end
+
+  context 'TreehouseAutomodExt' do
+    subject { described_class.new.call(account_username, 'foo.test', payload) }
+    let(:account_username) { 'evil' }
+    let(:account_display_name) { 'evil display name' }
+    let(:account_payload_suspended) { false }
+
+    let(:automod_account_username) { nil }
+
+    let(:payload) do
+      {
+        id: 'https://foo.test',
+        type: 'Actor',
+        inbox: 'https://foo.test/inbox',
+        suspended: account_payload_suspended,
+        name: account_display_name,
+      }.with_indifferent_access
+    end
+
+    let(:name_hash_hash) do
+      {
+        # 'evil' => 'evil display name'
+        '4034a346ccee15292d823416f7510a2f' => Set['225e44a7c4a792ee22a4ada2032da7cd']
+      }
+    end
+
+    before do
+      stub_const('ActivityPub::ProcessAccountService::TreehouseAutomodExt::HEURISTIC_AUTO_SUSPEND_ACTIVE', true)
+      stub_const('ActivityPub::ProcessAccountService::TreehouseAutomodExt::AUTOMOD_ACCOUNT_USERNAME', automod_account_username)
+
+      stub_const('ActivityPub::ProcessAccountService::TreehouseAutomodExt::HEURISTIC_NAMES', name_hash_hash)
+      stub_const('ActivityPub::ProcessAccountService::TreehouseAutomodExt::HEURISTIC_MAX_LEN', 20)
+    end
+
+    context 'new account' do
+      context 'heuristic matching' do
+        it 'suspends the user locally' do
+          expect(subject.suspended?).to be true
+          expect(subject.suspension_origin_local?).to be true
+        end
+      end
+
+      context 'heuristic not matching' do
+        let(:account_display_name) { '' }
+        it 'does nothing' do
+          expect(subject.suspended?).to be false
+        end
+      end
+    end
+
+    context 'existing account' do
+      let!(:account) { Fabricate(:account, username: account_username, domain: 'foo.test', display_name: account_display_name) }
+
+      before do
+        allow(Admin::SuspensionWorker).to receive(:perform_async)
+      end
+
+      context 'heuristic matching' do
+        it 'suspends the user locally' do
+          expect(subject.suspended?).to be true
+          expect(subject.suspension_origin_local?).to be true
+        end
+      end
+
+      context 'heuristic not matching' do
+        let(:account_display_name) { 'not evil display name' }
+
+        it 'does nothing' do
+          expect(subject.suspended?).to be false
+        end
+
+        context 'suspended locally' do
+          before do
+            account.suspend!(origin: :local)
+          end
+
+          it 'does nothing' do
+            expect(subject.suspended?).to be true
+          end
+        end
+      end
+    end
+
+    context 'tracking report' do
+      let(:automod_account_username) { 'automod_test' }
+
+      let!(:automod_user_role) { Fabricate(:user_role, name: 'Automod', permissions: UserRole::FLAGS[:administrator]) }
+
+      let!(:automod_account) do
+        account = Fabricate(:account, username: automod_account_username)
+        account.user.role_id = automod_user_role.id
+        account.user.save!
+        account
+      end
+
+      it 'creates report' do
+        expect(subject.targeted_reports.empty?).to be_falsy
+
+        report = Report.find_by(target_account_id: subject.id, account_id: automod_account.id, assigned_account_id: automod_account.id)
+        expect(report.comment.starts_with?('Tracking Report - automatically created by TreehouseAutomodExt')).to be_truthy
+      end
+
+      it 'creates account action' do
+        subject
+        expect(Admin::ActionLog.find_by(account_id: automod_account.id, target_id: subject.id)).not_to be nil
+      end
+    end
+  end
 end