add LOG_FAILED_LOGIN_ATTEMPTS (#2936)

* add failed login logs

* put failed login attempt logs behind a config option

* add changelog entry

* add config test

* add auth_controller tests

* move tests to separate non-async test module

---------

Co-authored-by: Uku Taht <Uku.taht@gmail.com>

CHANGELOG.md

@@ -9,6 +9,7 @@ All notable changes to this project will be documented in this file.
 - 'Last updated X seconds ago' info to 'current visitors' tooltips
 - Add support for more Bamboo adapters, i.e. `Bamboo.MailgunAdapter`, `Bamboo.MandrillAdapter`, `Bamboo.SendGridAdapter` plausible/analytics#2649
 - Ability to change domain for existing site (requires numeric IDs data migration, instructions will be provided separately) UI + API (`PUT /api/v1/sites`)
+- Add `LOG_FAILED_LOGIN_ATTEMPTS` environment variable to enable failed login attempts logs plausible/analytics#2936
 - Add `MAILER_NAME` environment variable support plausible/analytics#2937
 - Add `MAILGUN_BASE_URI` support for `Bamboo.MailgunAdapter` plausible/analytics#2935 
 

config/runtime.exs

@@ -217,6 +217,11 @@ disable_cron =
   |> get_var_from_path_or_env("DISABLE_CRON", "false")
   |> String.to_existing_atom()
 
+log_failed_login_attempts =
+  config_dir
+  |> get_var_from_path_or_env("LOG_FAILED_LOGIN_ATTEMPTS", "false")
+  |> String.to_existing_atom()
+
 config :plausible,
   environment: env,
   mailer_email: mailer_email,
@@ -224,7 +229,8 @@ config :plausible,
   site_limit: site_limit,
   site_limit_exempt: site_limit_exempt,
   is_selfhost: is_selfhost,
-  custom_script_name: custom_script_name
+  custom_script_name: custom_script_name,
+  log_failed_login_attempts: log_failed_login_attempts
 
 config :plausible, :selfhost,
   enable_email_verification: enable_email_verification,

lib/plausible_web/controllers/auth_controller.ex

@@ -371,12 +371,15 @@ defmodule PlausibleWeb.AuthController do
       |> redirect(to: login_dest)
     else
       :wrong_password ->
+        maybe_log_failed_login_attempts("wrong password for #{email}")
+
         render(conn, "login_form.html",
           error: "Wrong email or password. Please try again.",
           layout: {PlausibleWeb.LayoutView, "focus.html"}
         )
 
       :user_not_found ->
+        maybe_log_failed_login_attempts("user not found for #{email}")
         Plausible.Auth.Password.dummy_calculation()
 
         render(conn, "login_form.html",
@@ -385,6 +388,8 @@ defmodule PlausibleWeb.AuthController do
         )
 
       {:rate_limit, _} ->
+        maybe_log_failed_login_attempts("too many logging attempts for #{email}")
+
         render_error(
           conn,
           429,
@@ -393,6 +398,12 @@ defmodule PlausibleWeb.AuthController do
     end
   end
 
+  defp maybe_log_failed_login_attempts(message) do
+    if Application.get_env(:plausible, :log_failed_login_attempts) do
+      Logger.warning("[login] #{message}")
+    end
+  end
+
   @login_interval 60_000
   @login_limit 5
   defp check_ip_rate_limit(conn) do

test/plausible/config_test.exs

@@ -149,6 +149,23 @@ defmodule Plausible.ConfigTest do
     end
   end
 
+  describe "log_failed_login_attempts" do
+    test "can be true" do
+      env = {"LOG_FAILED_LOGIN_ATTEMPTS", "true"}
+      assert get_in(runtime_config(env), [:plausible, :log_failed_login_attempts]) == true
+    end
+
+    test "can be false" do
+      env = {"LOG_FAILED_LOGIN_ATTEMPTS", "false"}
+      assert get_in(runtime_config(env), [:plausible, :log_failed_login_attempts]) == false
+    end
+
+    test "is false by default" do
+      env = {"LOG_FAILED_LOGIN_ATTEMPTS", nil}
+      assert get_in(runtime_config(env), [:plausible, :log_failed_login_attempts]) == false
+    end
+  end
+
   defp runtime_config(env) do
     put_system_env_undo(env)
     Config.Reader.read!("config/runtime.exs", env: :prod)

test/plausible_web/controllers/auth_controller/logs_test.exs

@@ -0,0 +1,51 @@
+defmodule PlausibleWeb.AuthController.LogsTest do
+  use PlausibleWeb.ConnCase
+  import ExUnit.CaptureLog
+
+  describe "POST /login" do
+    setup do
+      patch_env(:log_failed_login_attempts, true)
+    end
+
+    test "logs on missing user", %{conn: conn} do
+      logs =
+        capture_log(fn ->
+          post(conn, "/login", email: "user@example.com", password: "password")
+        end)
+
+      assert logs =~ "[warning] [login] user not found for user@example.com"
+    end
+
+    test "logs on wrong password", %{conn: conn} do
+      user = insert(:user, password: "password")
+
+      logs =
+        capture_log(fn ->
+          post(conn, "/login", email: user.email, password: "wrong")
+        end)
+
+      assert logs =~ "[warning] [login] wrong password for #{user.email}"
+    end
+
+    test "logs on too many login attempts", %{conn: conn} do
+      user = insert(:user, password: "password")
+
+      capture_log(fn ->
+        for _ <- 1..5 do
+          build_conn()
+          |> put_req_header("x-forwarded-for", "1.1.1.1")
+          |> post("/login", email: user.email, password: "wrong")
+        end
+      end)
+
+      logs =
+        capture_log(fn ->
+          conn
+          |> put_req_header("x-forwarded-for", "1.1.1.1")
+          |> post("/login", email: user.email, password: "wrong")
+        end)
+
+      assert logs =~ "[warning] [login] too many logging attempts for #{user.email}"
+    end
+  end
+end