diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab5d635d3..66c95a0c3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 ## Current Master
 
+- Continuously update blacklist for known phishing sites in background.
+- Automatically detect suspicious URLs too similar to common phishing targets, and blacklist them.
+
 ## 3.9.2 2017-7-26
 
 - Fix bugs that could sometimes result in failed transactions after switching networks.
diff --git a/app/manifest.json b/app/manifest.json
index 55e1eb5b1..591a07d0d 100644
--- a/app/manifest.json
+++ b/app/manifest.json
@@ -55,8 +55,12 @@
     },
     {
       "run_at": "document_start",
-      "matches": ["http://*/*", "https://*/*"],
-      "js": ["scripts/blacklister.js"]
+      "matches": [
+        "http://*/*",
+        "https://*/*"
+      ],
+      "js": ["scripts/blacklister.js"],
+      "all_frames": true
     }
   ],
   "permissions": [
diff --git a/app/scripts/background.js b/app/scripts/background.js
index 7e8f9172f..bc0fbdc37 100644
--- a/app/scripts/background.js
+++ b/app/scripts/background.js
@@ -11,6 +11,7 @@ const NotificationManager = require('./lib/notification-manager.js')
 const MetamaskController = require('./metamask-controller')
 const extension = require('extensionizer')
 const firstTimeState = require('./first-time-state')
+const isPhish = require('./lib/is-phish')
 
 const STORAGE_KEY = 'metamask-config'
 const METAMASK_DEBUG = 'GULP_METAMASK_DEBUG'
@@ -90,8 +91,11 @@ function setupController (initState) {
 
   extension.runtime.onConnect.addListener(connectRemote)
   function connectRemote (remotePort) {
-    const name = remotePort.name
-    var isMetaMaskInternalProcess = name === 'popup' || name === 'notification' || name === 'ui'
+    if (remotePort.name === 'blacklister') {
+      return checkBlacklist(remotePort)
+    }
+
+    var isMetaMaskInternalProcess = remotePort.name === 'popup' || remotePort.name === 'notification'
     var portStream = new PortStream(remotePort)
     if (isMetaMaskInternalProcess) {
       // communication with popup
@@ -136,6 +140,27 @@ function setupController (initState) {
   return Promise.resolve()
 }
 
+// Listen for new pages and return if blacklisted:
+function checkBlacklist (port) {
+  const handler = handleNewPageLoad.bind(null, port)
+  port.onMessage.addListener(handler)
+  setTimeout(() => {
+    port.onMessage.removeListener(handler)
+  }, 30000)
+}
+
+function handleNewPageLoad (port, message) {
+  const { pageLoaded } = message
+  if (!pageLoaded || !global.metamaskController) return
+
+  const state = global.metamaskController.getState()
+  const updatedBlacklist = state.blacklist
+
+  if (isPhish({ updatedBlacklist, hostname: pageLoaded })) {
+    port.postMessage({ 'blacklist': pageLoaded })
+  }
+}
+
 //
 // Etc...
 //
diff --git a/app/scripts/blacklister.js b/app/scripts/blacklister.js
index 9337599cc..37751b595 100644
--- a/app/scripts/blacklister.js
+++ b/app/scripts/blacklister.js
@@ -1,41 +1,14 @@
-const levenshtein = require('fast-levenshtein')
-const blacklistedMetaMaskDomains = ['metamask.com']
-const blacklistedDomains = require('etheraddresslookup/blacklists/domains.json').concat(blacklistedMetaMaskDomains)
-const whitelistedMetaMaskDomains = ['metamask.io', 'www.metamask.io']
-const whitelistedDomains = require('etheraddresslookup/whitelists/domains.json').concat(whitelistedMetaMaskDomains)
-const LEVENSHTEIN_TOLERANCE = 4
-const LEVENSHTEIN_CHECKS = ['myetherwallet', 'myetheroll', 'ledgerwallet', 'metamask']
+const extension = require('extensionizer')
 
+var port = extension.runtime.connect({name: 'blacklister'})
+port.postMessage({ 'pageLoaded': window.location.hostname })
+port.onMessage.addListener(redirectIfBlacklisted)
 
-// credit to @sogoiii and @409H for their help!
-// Return a boolean on whether or not a phish is detected.
-function isPhish(hostname) {
-  var strCurrentTab = hostname
-
-  // check if the domain is part of the whitelist.
-  if (whitelistedDomains && whitelistedDomains.includes(strCurrentTab)) { return false }
-
-  // check if the domain is part of the blacklist.
-  var isBlacklisted = blacklistedDomains && blacklistedDomains.includes(strCurrentTab)
-
-  // check for similar values.
-  var levenshteinMatched = false
-  var levenshteinForm = strCurrentTab.replace(/\./g, '')
-  LEVENSHTEIN_CHECKS.forEach((element) => {
-    if (levenshtein.get(element, levenshteinForm) < LEVENSHTEIN_TOLERANCE) {
-      levenshteinMatched = true
-    }
-  })
-
-  return isBlacklisted || levenshteinMatched
-}
-
-window.addEventListener('load', function () {
-  var hostnameToCheck = window.location.hostname
-  if (isPhish(hostnameToCheck)) {
-    // redirect to our phishing warning page.
+function redirectIfBlacklisted (response) {
+  const { blacklist } = response
+  const host = window.location.hostname
+  if (blacklist && blacklist === host) {
     window.location.href = 'https://metamask.io/phishing.html'
   }
-})
+}
 
-module.exports = isPhish
diff --git a/app/scripts/controllers/infura.js b/app/scripts/controllers/infura.js
index b34b0bc03..97b2ab7e3 100644
--- a/app/scripts/controllers/infura.js
+++ b/app/scripts/controllers/infura.js
@@ -1,5 +1,6 @@
 const ObservableStore = require('obs-store')
 const extend = require('xtend')
+const recentBlacklist = require('etheraddresslookup/blacklists/domains.json')
 
 // every ten minutes
 const POLLING_INTERVAL = 300000
@@ -9,6 +10,7 @@ class InfuraController {
   constructor (opts = {}) {
     const initState = extend({
       infuraNetworkStatus: {},
+      blacklist: recentBlacklist,
     }, opts.initState)
     this.store = new ObservableStore(initState)
   }
@@ -30,12 +32,24 @@ class InfuraController {
       })
   }
 
+  updateLocalBlacklist () {
+    return fetch('https://api.infura.io/v1/blacklist')
+      .then(response => response.json())
+      .then((parsedResponse) => {
+        this.store.updateState({
+          blacklist: parsedResponse,
+        })
+        return parsedResponse
+      })
+  }
+
   scheduleInfuraNetworkCheck () {
     if (this.conversionInterval) {
       clearInterval(this.conversionInterval)
     }
     this.conversionInterval = setInterval(() => {
       this.checkInfuraNetworkStatus()
+      this.updateLocalBlacklist()
     }, POLLING_INTERVAL)
   }
 }
diff --git a/app/scripts/inpage.js b/app/scripts/inpage.js
index ec764535e..9e98c044b 100644
--- a/app/scripts/inpage.js
+++ b/app/scripts/inpage.js
@@ -65,3 +65,4 @@ function restoreContextAfterImports () {
     console.warn('MetaMask - global.define could not be overwritten.')
   }
 }
+
diff --git a/app/scripts/lib/is-phish.js b/app/scripts/lib/is-phish.js
new file mode 100644
index 000000000..68c09e4ac
--- /dev/null
+++ b/app/scripts/lib/is-phish.js
@@ -0,0 +1,38 @@
+const levenshtein = require('fast-levenshtein')
+const blacklistedMetaMaskDomains = ['metamask.com']
+let blacklistedDomains = require('etheraddresslookup/blacklists/domains.json').concat(blacklistedMetaMaskDomains)
+const whitelistedMetaMaskDomains = ['metamask.io', 'www.metamask.io']
+const whitelistedDomains = require('etheraddresslookup/whitelists/domains.json').concat(whitelistedMetaMaskDomains)
+const LEVENSHTEIN_TOLERANCE = 4
+const LEVENSHTEIN_CHECKS = ['myetherwallet', 'myetheroll', 'ledgerwallet', 'metamask']
+
+
+// credit to @sogoiii and @409H for their help!
+// Return a boolean on whether or not a phish is detected.
+function isPhish({ hostname, updatedBlacklist = null }) {
+  var strCurrentTab = hostname
+
+  // check if the domain is part of the whitelist.
+  if (whitelistedDomains && whitelistedDomains.includes(strCurrentTab)) { return false }
+
+  // Allow updating of blacklist:
+  if (updatedBlacklist) {
+    blacklistedDomains = blacklistedDomains.concat(updatedBlacklist)
+  }
+
+  // check if the domain is part of the blacklist.
+  const isBlacklisted = blacklistedDomains && blacklistedDomains.includes(strCurrentTab)
+
+  // check for similar values.
+  let levenshteinMatched = false
+  var levenshteinForm = strCurrentTab.replace(/\./g, '')
+  LEVENSHTEIN_CHECKS.forEach((element) => {
+    if (levenshtein.get(element, levenshteinForm) <= LEVENSHTEIN_TOLERANCE) {
+      levenshteinMatched = true
+    }
+  })
+
+  return isBlacklisted || levenshteinMatched
+}
+
+module.exports = isPhish
diff --git a/test/unit/blacklister-test.js b/test/unit/blacklister-test.js
index d9290795c..1badc2c8f 100644
--- a/test/unit/blacklister-test.js
+++ b/test/unit/blacklister-test.js
@@ -1,24 +1,24 @@
 const assert = require('assert')
-const Blacklister = require('../../app/scripts/blacklister')
-
+const isPhish = require('../../app/scripts/lib/is-phish')
 
 describe('blacklister', function () {
   describe('#isPhish', function () {
     it('should not flag whitelisted values', function () {
-      var result = Blacklister('www.metamask.io')
+      var result = isPhish({ hostname: 'www.metamask.io' })
       assert(!result)
     })
     it('should flag explicit values', function () {
-      var result = Blacklister('metamask.com')
+      var result = isPhish({ hostname: 'metamask.com' })
       assert(result)
     })
     it('should flag levenshtein values', function () {
-      var result = Blacklister('metmask.io')
+      var result = isPhish({ hostname: 'metmask.com' })
       assert(result)
     })
     it('should not flag not-even-close values', function () {
-      var result = Blacklister('example.com')
+      var result = isPhish({ hostname: 'example.com' })
       assert(!result)
     })
   })
 })
+