2 files changed, 41 insertions, 2 deletions
diff --git a/app/scripts/background.js b/app/scripts/background.js
index 01bb39186..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'
@@ -153,9 +154,9 @@ function handleNewPageLoad (port, message) {
   if (!pageLoaded || !global.metamaskController) return
 
   const state = global.metamaskController.getState()
-  const { blacklist } = state
+  const updatedBlacklist = state.blacklist
 
-  if (blacklist && blacklist.includes(pageLoaded)) {
+  if (isPhish({ updatedBlacklist, hostname: pageLoaded })) {
     port.postMessage({ 'blacklist': pageLoaded })
   }
 }
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