We noticed that the attack was carried out in multiple phases. The first phase appeared to be a testing stage and was conducted from March 3rd to March 6th. The initial test target was and the number of requests was artificially limited. From March 4rd to March 6th, the request limitations were removed.

The next phase was conducted between March 10th and 13th and targeted the following IP address at first: Passive DNS places hosts under the domain at this IP address. On March 13th, the attack was extended to include At first, requests were made over HTTP and then upgraded to to use HTTPS. On March 14th, the attack started for real and targeted both via HTTP as well as HTTPS. Attacks against this specific host were carried out until March 17th.

On March 18th, the number of hosts under attack was increased to include the following:,,,, This is also the first time we find truncated injections in which the Javascript is cut-off and non functional. At some point during this phase of the attack, the cloudfront hosts started serving 302 redirects to as well as other domains. Substitution of Javascript ceased completely on March 20th but injections into HTML pages continued. Whereas Javascript replacement breaks the functionality of the original content, injection into HTML does not. Here HTML is modified to include both a reference to the original content as well as the attack Javascript as shown below:

<meta name="referrer" content="never"/>
<title> </title>
      <iframe src="[...]?t=Zmh4cXpXJApHIDFMcjZa" style="position:absolute; left:0; top:0; height:100%; width:100%; border:0px;" scrolling="yes"></iframe>
<script type="text/javascript">
[... regular attack Javascript ...]

In this technique, the web browser fetches the same HTML page twice but due to the presence of the query parameter t, no injection happens on the second request. The attacked domains also changed and now consisted of:, and About 10 hours after this new phase started, we see 302 redirects to a different domain served from the targeted servers.

The attack against the cloudfront hosts stops on March 25th. Instead, resources hosted on were now under attack. The first new target was and was quickly followed by as well as

On March 26th, a packed and obfuscated attack Javascript replaced the plain version and started targeting the following resources: and Here we also observed some truncated injections. The attack against github seems to have stopped on April 7th, 2015 and marks the last time we saw injections during our measurement period.

From the beginning of March until the attacks stopped in April, we saw 19 unique Javascript replacement payloads as represented by their MD5 sum in the pie chart below.

For the HTML injections, the payloads were unique due to the injected URL so we are not showing their respective MD5 sums. However, the injected Javascript was very similar to the payloads referenced above.

Our systems saw injected content on the following eight domains and corresponding IP addresses:

  • (
  • (
  • (
  • (
  • (
  • (
  • (
  • (

The sizes of the injected Javascript payloads ranged from 995 to 1325 bytes.

We hope this report helps to round out the overall facts known about this attack. It also demonstrates that collectively there is a lot of visibility into what happens on the web. At the HTTP level seen by Safe Browsing, we cannot confidently attribute this attack to anyone. However, it makes it clear that hiding such attacks from detailed analysis after the fact is difficult.

Had the entire web already moved to encrypted traffic via TLS, such an injection attack would not have been possible. This provides further motivation for transitioning the web to encrypted and integrity-protected communication. Unfortunately, defending against such an attack is not easy for website operators. In this case, the attack Javascript requests web resources sequentially and slowing down responses might have helped with reducing the overall attack traffic. Another hope is that the external visibility of this attack will serve as a deterrent in the future.


Since 2008 we’ve been working to make sure all of our services use strong HTTPS encryption by default. That means people using products like Search, Gmail, YouTube, and Drive will automatically have an encrypted connection to Google. In addition to providing a secure connection on our own products, we’ve been big proponents of the idea of “HTTPS Everywhere,” encouraging webmasters to prevent and fix security breaches on their sites, and using HTTPS as a signal in our search ranking algorithm.

This year, we’re working to bring this “HTTPS Everywhere” mission to our ads products as well, to support all of our advertiser and publisher partners. Here are some of the specific initiatives we’re working on:

  • We’ve moved all YouTube ads to HTTPS as of the end of 2014.
  • Search on is already encrypted for a vast majority of users and we are working towards encrypting search ads across our systems.
  • By June 30, 2015, the vast majority of mobile, video, and desktop display ads served to the Google Display Network, AdMob, and DoubleClick publishers will be encrypted.
  • Also by June 30, 2015, advertisers using any of our buying platforms, including AdWords and DoubleClick, will be able to serve HTTPS-encrypted display ads to all HTTPS-enabled inventory.

Of course we’re not alone in this goal. By encrypting ads, the advertising industry can help make the internet a little safer for all users. Recently, the Interactive Advertising Bureau (IAB) published a call to action to adopt HTTPS ads, and many industry players are also working to meet HTTPS requirements. We’re big supporters of these industry-wide efforts to make HTTPS everywhere a reality.

Our HTTPS Everywhere ads initiatives will join some of our other efforts to provide a great ads experience online for our users, like “Why this Ad?”, “Mute This Ad” and TrueView skippable ads. With these security changes to our ads systems, we’re one step closer to ensuring users everywhere are safe and secure every time they choose to watch a video, map out a trip in a new city, or open their favorite app.


Last month, we posted about unwanted ad injectors, a common side-effect of installing unwanted software. Ad injectors are often annoying, but in some cases, they can jeopardize users’ security as well. Today, we want to shed more light on how ad injector software can hijack even encrypted SSL browser communications.

How ad injectors jeopardize security

In the example below, the ad injector software tampers with the security trust store that your browser uses to establish a secure connection with your Gmail. This can give the injector access to your personal data and make your computer vulnerable to a 'man in the middle' attack.
SSL hijacking is completely invisible to users because hijacked browser sessions appear like any other secure browser session. The screenshot on the left shows a normal connection to Gmail, the one on the right shows the difference when a SSL hijacker is installed.

You may recall the recent SuperFish/Komodia incident. As has been reported, the Komodia SSL hijacker did not properly verify secure connections and it was not using keys in a secure way. This type of software puts users at additional risk by making it possible for remote attackers to impersonate web sites and expose users’ private data.

How to stay safe

Safe Browsing protects users from several classes of unwanted software that expose users to such risk. However, it never hurts to remain cautious when downloading software or browsing the web. When you are visiting a secure site, like your email or online banking site, pay extra attention to any unusual changes to the site’s content. If you notice unusual changes, like extra ads, coupons, or surveys, this may be an indication that your computer is infected with this type of unwanted software. Please, also check out these tips to learn how you can stay safe on the web.

For software developers, if your software makes changes to the content of web sites, the safest way to make those changes is through a browser extension. This keeps users’ communications secure by relying on the browser’s security guarantees. Software that attempts to change browser behavior or content by any other means may be flagged as unwanted software.


We’re committed to making Android a safe ecosystem for users and developers. That’s why we built Android the way we did—with multiple layers of security in the platform itself and in the services Google provides. In addition to traditional protections like encryption and application sandboxes, these layers use both automated and manual review systems to keep the ecosystem safe from malware, phishing scams, fraud, and spam every day.

Android offers an application-focused platform security model rooted in a strong application sandbox. We also use data to improve security in near real time through a combination of reliable products and trusted services, like Google Play, and Verify Apps. And, because we are an open platform, third-party research and reports help make us stronger and users safer.

But, every now and then we like to check in to see how we’re doing. So, we’ve been working hard on a report that analyzes billions (!) of data points gathered every day during 2014 and provides comprehensive and in-depth insight into security of the Android ecosystem. We hope this will help us share our approaches and data-driven decisions with the security community in order to keep users safer and avoid risk.

It’s lengthy, so if you’ve only got a minute, we pulled out a few of the key findings here:
  • Over 1 billion devices are protected with Google Play which conducts 200 million security scans of devices per day.
  • Fewer than 1% of Android devices had a Potentially Harmful App (PHA) installed in 2014. Fewer than 0.15% of devices that only install from Google Play had a PHA installed.
  • The overall worldwide rate of Potentially Harmful Application (PHA) installs decreased by nearly 50% between Q1 and Q4 2014.
  • SafetyNet checks over 400 million connections per day for potential SSL issues.
  • Android and Android partners responded to 79 externally reported security issues, and over 25,000 applications in Google Play were updated following security notifications from Google Play.

We want to ensure that Android is a safe place, and this report has helped us take a look at how we did in the past year, and what we can still improve on. In 2015, we have already announced that we are being even more proactive in reviewing applications for all types of policy violations within Google Play. Outside of Google Play, we have also increased our efforts to enhance protections for specific higher-risk devices and regions.

As always, we are appreciate feedback on our report and suggestions for how we can improve Android. Contact us at


It’s tough to read the New York Times under these circumstances:
nytimes_bad NEW NEW.jpg
And it’s pretty unpleasant to shop for a Nexus 6 on a search results page that looks like this:
The browsers in the screenshots above have been infected with ‘ad injectors’. Ad injectors are programs that insert new ads, or replace existing ones, into the pages you visit while browsing the web. We’ve received more than 100,000 complaints from Chrome users about ad injection since the beginning of 2015—more than network errors, performance problems, or any other issue. 

Injectors are yet another symptom of “unwanted software”—programs that are deceptive, difficult to remove, secretly bundled with other downloads, and have other bad qualities. We’ve made several recent announcements about our work to fight unwanted software via Safe Browsing, and now we’re sharing some updates on our efforts to protect you from injectors as well. 

Unwanted ad injectors: disliked by users, advertisers, and publishers

Unwanted ad injectors aren’t part of a healthy ads ecosystem. They’re part of an environment where bad practices hurt users, advertisers, and publishers alike. 

People don’t like ad injectors for several reasons: not only are they intrusive, but people are often tricked into installing ad injectors in the first place, via deceptive advertising, or software “bundles.” Ad injection can also be a security risk, as the recent “Superfish” incident showed. 

But, ad injectors are problematic for advertisers and publishers as well. Advertisers often don’t know their ads are being injected, which means they don’t have any idea where their ads are running. Publishers, meanwhile, aren’t being compensated for these ads, and more importantly, they unknowingly may be putting their visitors in harm’s way, via spam or malware in the injected ads. 

How Google fights unwanted ad injectors

We have a variety of policies that either limit, or entirely prohibit, ad injectors. 

In Chrome, any extension hosted in the Chrome Web Store must comply with the Developer Program Policies. These require that extensions have a narrow and easy-to-understand purpose. We don’t ban injectors altogether—if they want to, people can still choose to install injectors that clearly disclose what they do—but injectors that sneak ads into a user’s browser would certainly violate our policies. We show people familiar red warnings when they are about to download software that is deceptive, or doesn’t use the right APIs to interact with browsers.
red warning.png
On the ads side, AdWords advertisers with software downloads hosted on their site, or linked to from their site, must comply with our Unwanted Software Policy. Additionally, both Google Platforms program policies and the DoubleClick Ad Exchange (AdX) Seller Program Guidelines, don’t allow programs that overlay ad space on a given site without permission of the site owner.

To increase awareness about ad injectors and the scale of this issue, we’ll be releasing new research on May 1 that examines the ad injector ecosystem in depth. The study, conducted with researchers at University of California Berkeley, drew conclusions from more than 100 million pageviews of Google sites across Chrome, Firefox, and Internet Explorer on various operating systems, globally. It’s not a pretty picture. Here’s a sample of the findings:
  • Ad injectors were detected on all operating systems (Mac and Windows), and web browsers (Chrome, Firefox, IE) that were included in our test.
  • More than 5% of people visiting Google sites have at least one ad injector installed. Within that group, half have at least two injectors installed and nearly one-third have at least four installed.
  • Thirty-four percent of Chrome extensions injecting ads were classified as outright malware.
  • Researchers found 192 deceptive Chrome extensions that affected 14 million users; these have since been disabled. Google now incorporates the techniques researchers used to catch these extensions to scan all new and updated extensions.

We’re constantly working to improve our product policies to protect people online. We encourage others to do the same. We’re committed to continuing to improve this experience for Google and the web as a whole.


Deceptive software disguised as a useful download harms your web experience by making undesired changes to your computer. Safe Browsing offers protection from such unwanted software by showing a warning in Chrome before you download these programs. In February we started showing additional warnings in Chrome before you visit a site that encourages downloads of unwanted software.

Today, we’re adding information about unwanted software to our Safe Browsing API.
In addition to our constantly-updated malware and phishing data, our unwanted software data is now publicly available for developers to integrate into their own security measures. For example, any app that wants to save its users from winding up on sites that lead to deceptive software could use our API to do precisely that.

We continue to integrate Safe Browsing technology across Google—in Chrome, Google Analytics, and more—to protect users. Our Safe Browsing API helps extend our malware, phishing, and unwanted software protection to keep more than 1.1 billion users safe online.

Check out our updated API documentation here.




[Cross-posted from the Chromium Blog]

Around this time each year we announce the rules, details and maximum cash amounts we’re putting up for our Pwnium competition. For the last few years we put a huge pile of cash on the table (last year it was e million) and gave researchers one day during CanSecWest to present their exploits. We’ve received some great entries over the years, but it’s time for something bigger.

Starting today, Pwnium will change its scope significantly, from a single-day competition held once a year at a security conference to a year round, worldwide opportunity for security researchers.

For those who are interested in what this means for the Pwnium rewards pool, we crunched the numbers and the results are in: it now goes all the way up to $∞ million*.

We’re making this change for a few reasons:

  • Removing barriers to entry: At Pwnium competitions, a security researcher would need to have a bug chain in March, pre-register, have a physical presence at the competition location and hopefully get a good timeslot. Under the new scheme, security researchers can submit their bugs year-round through the Chrome Vulnerability Reward Program (VRP) whenever they find them. 
  • Removing the incentive for bug hoarding: If a security researcher was to discover a Pwnium-quality bug chain today, it’s highly likely that they would wait until the contest to report it to get a cash reward. This is a bad scenario for all parties. It’s bad for us because the bug doesn’t get fixed immediately and our users are left at risk. It’s bad for them as they run the real risk of a bug collision. By allowing security researchers to submit bugs all year-round, collisions are significantly less likely and security researchers aren’t duplicating their efforts on the same bugs.
  • Our researchers want this: On top of all of these reasons, we asked our handful of participants if they wanted an option to report all year. They did, so we’re delivering.

Logistically, we’ll be adding Pwnium-style bug chains on Chrome OS to the Chrome VRP. This will increase our top reward to $50,000, which will be on offer all year-round. Check out our FAQ for more information.

Happy hunting!

*Our lawyercats wouldn’t let me say “never-ending” or “infinity million” without adding that “this is an experimental and discretionary rewards program and Google may cancel or modify the program at any time.” Check out the reward eligibility requirements on the Chrome VRP page.


SafeBrowsing helps keep you safe online and includes protection against unwanted software that makes undesirable changes to your computer or interferes with your online experience.

We recently expanded our efforts in Chrome, Search, and ads to keep you even safer from sites where these nefarious downloads are available.
  • Chrome: Now, in addition to showing warnings before you download unwanted software, Chrome will show you a new warning, like the one below, before you visit a site that encourages downloads of unwanted software.
  • Search: Google Search now incorporates signals that identify such deceptive sites. This change reduces the chances you’ll visit these sites via our search results.
  • Ads: We recently began to disable Google ads that lead to sites with unwanted software.

If you’re a site owner, we recommend that you register your site with Google Webmaster Tools. This will help you stay informed when we find something on your site that leads people to download unwanted software, and will provide you with helpful tips to resolve such issues. 

We’re constantly working to keep people safe across the web. Read more about Safe Browsing technology and our work to protect users here.