chrome/renderer/safe_browsing/phishing_dom_feature_extractor.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/renderer/safe_browsing/phishing_dom_feature_extractor.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/containers/hash_tables.h"
  10 #include "base/location.h"
  11 #include "base/logging.h"
  12 #include "base/metrics/histogram.h"
  13 #include "base/single_thread_task_runner.h"
  14 #include "base/strings/string_util.h"
  15 #include "base/thread_task_runner_handle.h"
  16 #include "base/time/time.h"
  17 #include "chrome/renderer/safe_browsing/feature_extractor_clock.h"
  18 #include "chrome/renderer/safe_browsing/features.h"
  19 #include "content/public/renderer/render_view.h"
  20 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
  21 #include "third_party/WebKit/public/platform/WebString.h"
  22 #include "third_party/WebKit/public/web/WebElement.h"
  23 #include "third_party/WebKit/public/web/WebElementCollection.h"
  24 #include "third_party/WebKit/public/web/WebLocalFrame.h"
  25 #include "third_party/WebKit/public/web/WebView.h"
  26
  27 namespace safe_browsing {
  28
  29 // This time should be short enough that it doesn't noticeably disrupt the
  30 // user's interaction with the page.
  31 const int PhishingDOMFeatureExtractor::kMaxTimePerChunkMs = 10;
  32
  33 // Experimenting shows that we get a reasonable gain in performance by
  34 // increasing this up to around 10, but there's not much benefit in
  35 // increasing it past that.
  36 const int PhishingDOMFeatureExtractor::kClockCheckGranularity = 10;
  37
  38 // This should be longer than we expect feature extraction to take on any
  39 // actual phishing page.
  40 const int PhishingDOMFeatureExtractor::kMaxTotalTimeMs = 500;
  41
  42 // Intermediate state used for computing features.  See features.h for
  43 // descriptions of the DOM features that are computed.
  44 struct PhishingDOMFeatureExtractor::PageFeatureState {
  45   // Link related features
  46   int external_links;
  47   base::hash_set<std::string> external_domains;
  48   int secure_links;
  49   int total_links;
  50
  51   // Form related features
  52   int num_forms;
  53   int num_text_inputs;
  54   int num_pswd_inputs;
  55   int num_radio_inputs;
  56   int num_check_inputs;
  57   int action_other_domain;
  58   int total_actions;
  59   base::hash_set<std::string> page_action_urls;
  60
  61   // Image related features
  62   int img_other_domain;
  63   int total_imgs;
  64
  65   // How many script tags
  66   int num_script_tags;
  67
  68   // The time at which we started feature extraction for the current page.
  69   base::TimeTicks start_time;
  70
  71   // The number of iterations we've done for the current extraction.
  72   int num_iterations;
  73
  74   explicit PageFeatureState(base::TimeTicks start_time_ticks)
  75       : external_links(0),
  76         secure_links(0),
  77         total_links(0),
  78         num_forms(0),
  79         num_text_inputs(0),
  80         num_pswd_inputs(0),
  81         num_radio_inputs(0),
  82         num_check_inputs(0),
  83         action_other_domain(0),
  84         total_actions(0),
  85         img_other_domain(0),
  86         total_imgs(0),
  87         num_script_tags(0),
  88         start_time(start_time_ticks),
  89         num_iterations(0) {}
  90
  91   ~PageFeatureState() {}
  92 };
  93
  94 // Per-frame state
  95 struct PhishingDOMFeatureExtractor::FrameData {
  96   // This is our reference to document.all, which is an iterator over all
  97   // of the elements in the document.  It keeps track of our current position.
  98   blink::WebElementCollection elements;
  99   // The domain of the document URL, stored here so that we don't need to
 100   // recompute it every time it's needed.
 101   std::string domain;
 102 };
 103
 104 PhishingDOMFeatureExtractor::PhishingDOMFeatureExtractor(
 105     content::RenderView* render_view,
 106     FeatureExtractorClock* clock)
 107     : render_view_(render_view),
 108       clock_(clock),
 109       weak_factory_(this) {
 110   Clear();
 111 }
 112
 113 PhishingDOMFeatureExtractor::~PhishingDOMFeatureExtractor() {
 114   // The RenderView should have called CancelPendingExtraction() before
 115   // we are destroyed.
 116   CheckNoPendingExtraction();
 117 }
 118
 119 void PhishingDOMFeatureExtractor::ExtractFeatures(
 120     FeatureMap* features,
 121     const DoneCallback& done_callback) {
 122   // The RenderView should have called CancelPendingExtraction() before
 123   // starting a new extraction, so DCHECK this.
 124   CheckNoPendingExtraction();
 125   // However, in an opt build, we will go ahead and clean up the pending
 126   // extraction so that we can start in a known state.
 127   CancelPendingExtraction();
 128
 129   features_ = features;
 130   done_callback_ = done_callback;
 131
 132   page_feature_state_.reset(new PageFeatureState(clock_->Now()));
 133   blink::WebView* web_view = render_view_->GetWebView();
 134   if (web_view && web_view->mainFrame()) {
 135     cur_document_ = web_view->mainFrame()->document();
 136   }
 137
 138   base::ThreadTaskRunnerHandle::Get()->PostTask(
 139       FROM_HERE,
 140       base::Bind(&PhishingDOMFeatureExtractor::ExtractFeaturesWithTimeout,
 141                  weak_factory_.GetWeakPtr()));
 142 }
 143
 144 void PhishingDOMFeatureExtractor::CancelPendingExtraction() {
 145   // Cancel any pending callbacks, and clear our state.
 146   weak_factory_.InvalidateWeakPtrs();
 147   Clear();
 148 }
 149
 150 void PhishingDOMFeatureExtractor::ExtractFeaturesWithTimeout() {
 151   DCHECK(page_feature_state_.get());
 152   ++page_feature_state_->num_iterations;
 153   base::TimeTicks current_chunk_start_time = clock_->Now();
 154
 155   if (cur_document_.isNull()) {
 156     // This will only happen if we weren't able to get the document for the
 157     // main frame.  We'll treat this as an extraction failure.
 158     RunCallback(false);
 159     return;
 160   }
 161
 162   int num_elements = 0;
 163   for (; !cur_document_.isNull(); cur_document_ = GetNextDocument()) {
 164     blink::WebElement cur_element;
 165     if (cur_frame_data_.get()) {
 166       // We're resuming traversal of a frame, so just advance to the next
 167       // element.
 168       cur_element = cur_frame_data_->elements.nextItem();
 169       // When we resume the traversal, the first call to nextItem() potentially
 170       // has to walk through the document again from the beginning, if it was
 171       // modified between our chunks of work.  Log how long this takes, so we
 172       // can tell if it's too slow.
 173       UMA_HISTOGRAM_TIMES("SBClientPhishing.DOMFeatureResumeTime",
 174                           clock_->Now() - current_chunk_start_time);
 175     } else {
 176       // We just moved to a new frame, so update our frame state
 177       // and advance to the first element.
 178       ResetFrameData();
 179       cur_element = cur_frame_data_->elements.firstItem();
 180     }
 181
 182     for (; !cur_element.isNull();
 183          cur_element = cur_frame_data_->elements.nextItem()) {
 184       if (cur_element.hasHTMLTagName("a")) {
 185         HandleLink(cur_element);
 186       } else if (cur_element.hasHTMLTagName("form")) {
 187         HandleForm(cur_element);
 188       } else if (cur_element.hasHTMLTagName("img")) {
 189         HandleImage(cur_element);
 190       } else if (cur_element.hasHTMLTagName("input")) {
 191         HandleInput(cur_element);
 192       } else if (cur_element.hasHTMLTagName("script")) {
 193         HandleScript(cur_element);
 194       }
 195
 196       if (++num_elements >= kClockCheckGranularity) {
 197         num_elements = 0;
 198         base::TimeTicks now = clock_->Now();
 199         if (now - page_feature_state_->start_time >=
 200             base::TimeDelta::FromMilliseconds(kMaxTotalTimeMs)) {
 201           DLOG(ERROR) << "Feature extraction took too long, giving up";
 202           // We expect this to happen infrequently, so record when it does.
 203           UMA_HISTOGRAM_COUNTS("SBClientPhishing.DOMFeatureTimeout", 1);
 204           RunCallback(false);
 205           return;
 206         }
 207         base::TimeDelta chunk_elapsed = now - current_chunk_start_time;
 208         if (chunk_elapsed >=
 209             base::TimeDelta::FromMilliseconds(kMaxTimePerChunkMs)) {
 210           // The time limit for the current chunk is up, so post a task to
 211           // continue extraction.
 212           //
 213           // Record how much time we actually spent on the chunk. If this is
 214           // much higher than kMaxTimePerChunkMs, we may need to adjust the
 215           // clock granularity.
 216           UMA_HISTOGRAM_TIMES("SBClientPhishing.DOMFeatureChunkTime",
 217                               chunk_elapsed);
 218           base::ThreadTaskRunnerHandle::Get()->PostTask(
 219               FROM_HERE,
 220               base::Bind(
 221                   &PhishingDOMFeatureExtractor::ExtractFeaturesWithTimeout,
 222                   weak_factory_.GetWeakPtr()));
 223           return;
 224         }
 225         // Otherwise, continue.
 226       }
 227     }
 228
 229     // We're done with this frame, recalculate the FrameData when we
 230     // advance to the next frame.
 231     cur_frame_data_.reset();
 232   }
 233
 234   InsertFeatures();
 235   RunCallback(true);
 236 }
 237
 238 void PhishingDOMFeatureExtractor::HandleLink(
 239     const blink::WebElement& element) {
 240   // Count the number of times we link to a different host.
 241   if (!element.hasAttribute("href")) {
 242     DVLOG(1) << "Skipping anchor tag with no href";
 243     return;
 244   }
 245
 246   // Retrieve the link and resolve the link in case it's relative.
 247   blink::WebURL full_url = element.document().completeURL(
 248       element.getAttribute("href"));
 249
 250   std::string domain;
 251   bool is_external = IsExternalDomain(full_url, &domain);
 252   if (domain.empty()) {
 253     DVLOG(1) << "Could not extract domain from link: " << full_url;
 254     return;
 255   }
 256
 257   if (is_external) {
 258     ++page_feature_state_->external_links;
 259
 260     // Record each unique domain that we link to.
 261     page_feature_state_->external_domains.insert(domain);
 262   }
 263
 264   // Check how many are https links.
 265   if (GURL(full_url).SchemeIs("https")) {
 266     ++page_feature_state_->secure_links;
 267   }
 268
 269   ++page_feature_state_->total_links;
 270 }
 271
 272 void PhishingDOMFeatureExtractor::HandleForm(
 273     const blink::WebElement& element) {
 274   // Increment the number of forms on this page.
 275   ++page_feature_state_->num_forms;
 276
 277   // Record whether the action points to a different domain.
 278   if (!element.hasAttribute("action")) {
 279     return;
 280   }
 281
 282   blink::WebURL full_url = element.document().completeURL(
 283       element.getAttribute("action"));
 284
 285   page_feature_state_->page_action_urls.insert(full_url.string().utf8());
 286
 287   std::string domain;
 288   bool is_external = IsExternalDomain(full_url, &domain);
 289   if (domain.empty()) {
 290     DVLOG(1) << "Could not extract domain from form action: " << full_url;
 291     return;
 292   }
 293
 294   if (is_external) {
 295     ++page_feature_state_->action_other_domain;
 296   }
 297   ++page_feature_state_->total_actions;
 298 }
 299
 300 void PhishingDOMFeatureExtractor::HandleImage(
 301     const blink::WebElement& element) {
 302   if (!element.hasAttribute("src")) {
 303     DVLOG(1) << "Skipping img tag with no src";
 304   }
 305
 306   // Record whether the image points to a different domain.
 307   blink::WebURL full_url = element.document().completeURL(
 308       element.getAttribute("src"));
 309   std::string domain;
 310   bool is_external = IsExternalDomain(full_url, &domain);
 311   if (domain.empty()) {
 312     DVLOG(1) << "Could not extract domain from image src: " << full_url;
 313     return;
 314   }
 315
 316   if (is_external) {
 317     ++page_feature_state_->img_other_domain;
 318   }
 319   ++page_feature_state_->total_imgs;
 320 }
 321
 322 void PhishingDOMFeatureExtractor::HandleInput(
 323     const blink::WebElement& element) {
 324   // The HTML spec says that if the type is unspecified, it defaults to text.
 325   // In addition, any unrecognized type will be treated as a text input.
 326   //
 327   // Note that we use the attribute value rather than
 328   // WebFormControlElement::formControlType() for consistency with the
 329   // way the phishing classification model is created.
 330   std::string type = element.getAttribute("type").utf8();
 331   base::StringToLowerASCII(&type);
 332   if (type == "password") {
 333     ++page_feature_state_->num_pswd_inputs;
 334   } else if (type == "radio") {
 335     ++page_feature_state_->num_radio_inputs;
 336   } else if (type == "checkbox") {
 337     ++page_feature_state_->num_check_inputs;
 338   } else if (type != "submit" && type != "reset" && type != "file" &&
 339              type != "hidden" && type != "image" && type != "button") {
 340     // Note that there are a number of new input types in HTML5 that are not
 341     // handled above.  For now, we will consider these as text inputs since
 342     // they could be used to capture user input.
 343     ++page_feature_state_->num_text_inputs;
 344   }
 345 }
 346
 347 void PhishingDOMFeatureExtractor::HandleScript(
 348     const blink::WebElement& element) {
 349   ++page_feature_state_->num_script_tags;
 350 }
 351
 352 void PhishingDOMFeatureExtractor::CheckNoPendingExtraction() {
 353   DCHECK(done_callback_.is_null());
 354   DCHECK(!cur_frame_data_.get());
 355   DCHECK(cur_document_.isNull());
 356   if (!done_callback_.is_null() || cur_frame_data_.get() ||
 357       !cur_document_.isNull()) {
 358     LOG(ERROR) << "Extraction in progress, missing call to "
 359                << "CancelPendingExtraction";
 360   }
 361 }
 362
 363 void PhishingDOMFeatureExtractor::RunCallback(bool success) {
 364   // Record some timing stats that we can use to evaluate feature extraction
 365   // performance.  These include both successful and failed extractions.
 366   DCHECK(page_feature_state_.get());
 367   UMA_HISTOGRAM_COUNTS("SBClientPhishing.DOMFeatureIterations",
 368                        page_feature_state_->num_iterations);
 369   UMA_HISTOGRAM_TIMES("SBClientPhishing.DOMFeatureTotalTime",
 370                       clock_->Now() - page_feature_state_->start_time);
 371
 372   DCHECK(!done_callback_.is_null());
 373   done_callback_.Run(success);
 374   Clear();
 375 }
 376
 377 void PhishingDOMFeatureExtractor::Clear() {
 378   features_ = NULL;
 379   done_callback_.Reset();
 380   cur_frame_data_.reset(NULL);
 381   cur_document_.reset();
 382 }
 383
 384 void PhishingDOMFeatureExtractor::ResetFrameData() {
 385   DCHECK(!cur_document_.isNull());
 386   DCHECK(!cur_frame_data_.get());
 387
 388   cur_frame_data_.reset(new FrameData());
 389   cur_frame_data_->elements = cur_document_.all();
 390   cur_frame_data_->domain =
 391       net::registry_controlled_domains::GetDomainAndRegistry(
 392           cur_document_.url(),
 393           net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
 394 }
 395
 396 blink::WebDocument PhishingDOMFeatureExtractor::GetNextDocument() {
 397   DCHECK(!cur_document_.isNull());
 398   blink::WebFrame* frame = cur_document_.frame();
 399   // Advance to the next frame that contains a document, with no wrapping.
 400   if (frame) {
 401     for (frame = frame->traverseNext(false); frame;
 402          frame = frame->traverseNext(false)) {
 403       if (!frame->document().isNull()) {
 404         return frame->document();
 405       }
 406     }
 407   } else {
 408     // Keep track of how often frame traversal got "stuck" due to the
 409     // current subdocument getting removed from the frame tree.
 410     UMA_HISTOGRAM_COUNTS("SBClientPhishing.DOMFeatureFrameRemoved", 1);
 411   }
 412   return blink::WebDocument();
 413 }
 414
 415 bool PhishingDOMFeatureExtractor::IsExternalDomain(const GURL& url,
 416                                                    std::string* domain) const {
 417   DCHECK(domain);
 418   DCHECK(cur_frame_data_.get());
 419
 420   if (cur_frame_data_->domain.empty()) {
 421     return false;
 422   }
 423
 424   // TODO(bryner): Ensure that the url encoding is consistent with the features
 425   // in the model.
 426   if (url.HostIsIPAddress()) {
 427     domain->assign(url.host());
 428   } else {
 429     domain->assign(net::registry_controlled_domains::GetDomainAndRegistry(
 430         url, net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES));
 431   }
 432
 433   return !domain->empty() && *domain != cur_frame_data_->domain;
 434 }
 435
 436 void PhishingDOMFeatureExtractor::InsertFeatures() {
 437   DCHECK(page_feature_state_.get());
 438
 439   if (page_feature_state_->total_links > 0) {
 440     // Add a feature for the fraction of times the page links to an external
 441     // domain vs. an internal domain.
 442     double link_freq = static_cast<double>(
 443         page_feature_state_->external_links) /
 444         page_feature_state_->total_links;
 445     features_->AddRealFeature(features::kPageExternalLinksFreq, link_freq);
 446
 447     // Add a feature for each unique domain that we're linking to
 448     for (const auto& domain : page_feature_state_->external_domains) {
 449       features_->AddBooleanFeature(features::kPageLinkDomain + domain);
 450     }
 451
 452     // Fraction of links that use https.
 453     double secure_freq = static_cast<double>(
 454         page_feature_state_->secure_links) / page_feature_state_->total_links;
 455     features_->AddRealFeature(features::kPageSecureLinksFreq, secure_freq);
 456   }
 457
 458   // Record whether forms appear and whether various form elements appear.
 459   if (page_feature_state_->num_forms > 0) {
 460     features_->AddBooleanFeature(features::kPageHasForms);
 461   }
 462   if (page_feature_state_->num_text_inputs > 0) {
 463     features_->AddBooleanFeature(features::kPageHasTextInputs);
 464   }
 465   if (page_feature_state_->num_pswd_inputs > 0) {
 466     features_->AddBooleanFeature(features::kPageHasPswdInputs);
 467   }
 468   if (page_feature_state_->num_radio_inputs > 0) {
 469     features_->AddBooleanFeature(features::kPageHasRadioInputs);
 470   }
 471   if (page_feature_state_->num_check_inputs > 0) {
 472     features_->AddBooleanFeature(features::kPageHasCheckInputs);
 473   }
 474
 475   // Record fraction of form actions that point to a different domain.
 476   if (page_feature_state_->total_actions > 0) {
 477     double action_freq = static_cast<double>(
 478         page_feature_state_->action_other_domain) /
 479         page_feature_state_->total_actions;
 480     features_->AddRealFeature(features::kPageActionOtherDomainFreq,
 481                               action_freq);
 482   }
 483
 484   // Add a feature for each unique external action url.
 485   for (const auto& url : page_feature_state_->page_action_urls) {
 486     features_->AddBooleanFeature(features::kPageActionURL + url);
 487   }
 488
 489   // Record how many image src attributes point to a different domain.
 490   if (page_feature_state_->total_imgs > 0) {
 491     double img_freq = static_cast<double>(
 492         page_feature_state_->img_other_domain) /
 493         page_feature_state_->total_imgs;
 494     features_->AddRealFeature(features::kPageImgOtherDomainFreq, img_freq);
 495   }
 496
 497   // Record number of script tags (discretized for numerical stability.)
 498   if (page_feature_state_->num_script_tags > 1) {
 499     features_->AddBooleanFeature(features::kPageNumScriptTagsGTOne);
 500     if (page_feature_state_->num_script_tags > 6) {
 501       features_->AddBooleanFeature(features::kPageNumScriptTagsGTSix);
 502     }
 503   }
 504 }
 505
 506 }  // namespace safe_browsing