diff --git a/Gemfile b/Gemfile
index e91c3ae..05c4432 100644
--- a/Gemfile
+++ b/Gemfile
@@ -39,6 +39,8 @@ gem 'jbuilder', '~> 2.5'
 
 # Use Capistrano for deployment
 # gem 'capistrano-rails', group: :development
+gem 'activerecord-session_store'
+gem 'rack-attack'
 
 group :development, :test do
   gem 'rspec-rails'
@@ -48,6 +50,8 @@ end
 
 group :development do
   gem 'faker'
+  gem 'brakeman'
+  gem 'bundler-audit'
 
   # Access an IRB console on exception pages or by using <%= console %> anywhere in the code.
   gem 'web-console', '>= 3.3.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 30c443b..5390679 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -33,6 +33,12 @@ GEM
       activemodel (= 5.0.2)
       activesupport (= 5.0.2)
       arel (~> 7.0)
+    activerecord-session_store (1.1.0)
+      actionpack (>= 4.0, < 5.2)
+      activerecord (>= 4.0, < 5.2)
+      multi_json (~> 1.11, >= 1.11.2)
+      rack (>= 1.5.2, < 3)
+      railties (>= 4.0, < 5.2)
     activesupport (5.0.2)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (~> 0.7)
@@ -46,7 +52,11 @@ GEM
     bootstrap-sass (3.3.7)
       autoprefixer-rails (>= 5.2.1)
       sass (>= 3.3.4)
+    brakeman (4.0.1)
     builder (3.2.3)
+    bundler-audit (0.6.0)
+      bundler (~> 1.2)
+      thor (~> 0.18)
     byebug (9.0.6)
     coffee-rails (4.2.1)
       coffee-script (>= 2.2.0)
@@ -98,6 +108,8 @@ GEM
     orm_adapter (0.5.0)
     puma (3.8.2)
     rack (2.0.1)
+    rack-attack (5.0.1)
+      rack
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (5.0.2)
@@ -191,7 +203,10 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  activerecord-session_store
   bootstrap-sass
+  brakeman
+  bundler-audit
   byebug
   coffee-rails (~> 4.2)
   devise
@@ -200,6 +215,7 @@ DEPENDENCIES
   jquery-rails
   listen (~> 3.0.5)
   puma (~> 3.0)
+  rack-attack
   rails (~> 5.0.2)
   rspec-rails
   sass-rails (~> 5.0)
@@ -212,4 +228,4 @@ DEPENDENCIES
   web-console (>= 3.3.0)
 
 BUNDLED WITH
-   1.14.6
+   1.16.0.pre.2
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 682a07d..cd6ea53 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -1,6 +1,6 @@
 class ApplicationController < ActionController::Base
 
-  # protect_from_forgery with: :exception
+  protect_from_forgery with: :exception
 
   helper_method :current_cart
 
diff --git a/app/controllers/events_controller.rb b/app/controllers/events_controller.rb
index 245dece..8f28b01 100644
--- a/app/controllers/events_controller.rb
+++ b/app/controllers/events_controller.rb
@@ -9,10 +9,10 @@ def show
     @comments = @event.comments
 
     if params[:keyword]
-      @comments = @comments.where( "comments.content LIKE '%#{params[:keyword]}%'")
+      @comments = @comments.where( "comments.content LIKE ?", "%#{params[:keyword]}%")
     end
 
-    if params[:sort]
+    if params[:sort] && ["id DESC", "id ASC"].include?(params[:sort])
       @comments = @comments.order(params[:sort])
     end
 
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index f1d232d..fd6cac4 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -21,7 +21,7 @@ def update
   protected
 
   def user_params
-    params.require(:user).permit(:nickname, :role)
+    params.require(:user).permit(:nickname)
   end
 
 end
diff --git a/app/helpers/users_helper.rb b/app/helpers/users_helper.rb
index ed49051..1d62a20 100644
--- a/app/helpers/users_helper.rb
+++ b/app/helpers/users_helper.rb
@@ -7,9 +7,7 @@ def user_avatar_link(user)
     email_md5 = Digest::MD5.hexdigest(user.email)
     gravatar_url = "https://www.gravatar.com/avatar/#{email_md5}"
 
-    str = "<div class ='user-link'>" + link_to(image_tag(gravatar_url), user_path(user)) + " " + user.display_name + "</div>"
-
-    str.html_safe
+    "<div class ='user-link'>".html_safe + link_to(image_tag(gravatar_url), user_path(user)) + " " + user.display_name + "</div>".html_safe
   end
 
 end
diff --git a/app/views/events/show.html.erb b/app/views/events/show.html.erb
index 0e89067..2996fec 100644
--- a/app/views/events/show.html.erb
+++ b/app/views/events/show.html.erb
@@ -22,14 +22,14 @@
     </div>
 
     <div class="panel-body">
-      <%= raw comment.content %>
+      <%= sanitize comment.content %>
     </div>
 
     <div class="panel-footer text-right">
       <%= comment.created_at.to_s %>
 
       <% if current_user && current_user.is_admin? %>
-        <%= link_to "Highligh", highlight_event_comment_path(@event, comment), :class => "btn btn-default" %>
+        <%= link_to "Highligh", highlight_event_comment_path(@event, comment), :method => :post, :class => "btn btn-default" %>
       <% end %>
 
       <% if comment.can_deleted_by(current_user) %>
@@ -50,4 +50,4 @@
   <div class="form-group">
     <%= f.submit "Comment", :class => "btn btn-primary" %>
   </div>
-<% end %>
\ No newline at end of file
+<% end %>
diff --git a/config/application.rb b/config/application.rb
index 2d9ee51..a8be62d 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -12,8 +12,9 @@ class Application < Rails::Application
     # Application configuration should go into files in config/initializers
     # -- all .rb files in that directory are automatically loaded.
     config.time_zone = "Beijing"
+    config.middleware.use Rack::Attack
 
   end
 end
 
-Time::DATE_FORMATS.merge!(:default => '%Y/%m/%d %I:%M %p', :ymd => '%Y/%m/%d')
\ No newline at end of file
+Time::DATE_FORMATS.merge!(:default => '%Y/%m/%d %I:%M %p', :ymd => '%Y/%m/%d')
diff --git a/config/initializers/rack-attack.rb b/config/initializers/rack-attack.rb
new file mode 100644
index 0000000..61a40b9
--- /dev/null
+++ b/config/initializers/rack-attack.rb
@@ -0,0 +1,59 @@
+class Rack::Attack
+
+  throttle('req/ip', :limit => 180, :period => 1.minutes) do |req|
+    req.ip
+  end
+
+  ### Prevent Brute-Force Login Attacks ###
+
+
+  # The most common brute-force login attack is a brute-force password
+
+  # attack where an attacker simply tries a large number of emails and
+
+  # passwords to see if any credentials match.
+
+  #
+
+  # Another common method of attack is to use a swarm of computers with
+
+  # different IPs to try brute-forcing a password for a specific account.
+
+
+  # Throttle POST requests to /login by IP address
+
+  #
+
+  # Key: "rack::attack:#{Time.now.to_i/:period}:logins/ip:#{req.ip}"
+
+  throttle('logins/ip', :limit => 5, :period => 20.seconds) do |req|
+    if req.path == '/users/sign_in' && req.post?
+      req.ip
+    end
+  end
+
+  # Throttle POST requests to /login by email param
+
+  #
+
+  # Key: "rack::attack:#{Time.now.to_i/:period}:logins/email:#{req.email}"
+
+  #
+
+  # Note: This creates a problem where a malicious user could intentionally
+
+  # throttle logins for another user and force their login requests to be
+
+  # denied, but that's not very common and shouldn't happen to you. (Knock
+
+  # on wood!)
+
+  throttle("logins/email", :limit => 5, :period => 20.seconds) do |req|
+    if req.path == '/users/sign_in' && req.post?
+      # return the email if present, nil otherwise
+
+      req.params['email'].presence
+    end
+  end
+
+end
diff --git a/config/initializers/session_store.rb b/config/initializers/session_store.rb
index 57e29c2..4b19248 100644
--- a/config/initializers/session_store.rb
+++ b/config/initializers/session_store.rb
@@ -1,3 +1,3 @@
 # Be sure to restart your server when you modify this file.
 
-Rails.application.config.session_store :cookie_store, key: '_hackme-app_session'
+Rails.application.config.session_store :active_record_store, key: 'my_app_session'
diff --git a/config/routes.rb b/config/routes.rb
index 2cfd938..a5ccf3e 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -7,7 +7,7 @@
   resources :events do
     resources :comments do
       member do
-        get :highlight
+        post :highlight
       end
     end
   end
diff --git a/db/migrate/20171001091950_add_sessions_table.rb b/db/migrate/20171001091950_add_sessions_table.rb
new file mode 100644
index 0000000..e0b41c7
--- /dev/null
+++ b/db/migrate/20171001091950_add_sessions_table.rb
@@ -0,0 +1,12 @@
+class AddSessionsTable < ActiveRecord::Migration
+  def change
+    create_table :sessions do |t|
+      t.string :session_id, :null => false
+      t.text :data
+      t.timestamps
+    end
+
+    add_index :sessions, :session_id, :unique => true
+    add_index :sessions, :updated_at
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 125d807..4b52cee 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170515030849) do
+ActiveRecord::Schema.define(version: 20171001091950) do
 
   create_table "cart_items", force: :cascade do |t|
     t.integer  "cart_id"
@@ -53,6 +53,15 @@
     t.datetime "updated_at",  null: false
   end
 
+  create_table "sessions", force: :cascade do |t|
+    t.string   "session_id", null: false
+    t.text     "data"
+    t.datetime "created_at"
+    t.datetime "updated_at"
+    t.index ["session_id"], name: "index_sessions_on_session_id", unique: true
+    t.index ["updated_at"], name: "index_sessions_on_updated_at"
+  end
+
   create_table "users", force: :cascade do |t|
     t.string   "email",                  default: "", null: false
     t.string   "encrypted_password",     default: "", null: false