Tag Archives: malware

#NoHacked: A year in review

We hope your year started out safe and secure!
We wanted to share with you a summary of our 2016 work as we continue our #NoHacked campaign. Let’s start with some trends on hacked sites from the past year.

State of Website Security in 2016

First off, some unfortunate news. We’ve seen an increase in the number of hacked sites by approximately 32% in 2016 compared to 2015. We don’t expect this trend to slow down. As hackers get more aggressive and more sites become outdated, hackers will continue to capitalize by infecting more sites.
On the bright side, 84% webmasters who do apply for reconsideration are successful in cleaning their sites. However, 61% of webmasters who were hacked never received a notification from Google that their site was infected because their sites weren't verified in Search Console. Remember to register for Search Console if you own or manage a site. It’s the primary channel that Google uses to communicate site health alerts.

More Help for Hacked Webmasters


We’ve been listening to your feedback to better understand how we can help webmasters with security issues. One of the top requests was easier to understand documentation about hacked sites. As a result we’ve been hard at work to make our documentation more useful.
First, we created new documentation to give webmasters more context when their site has been compromised. Here is a list of the new help documentation:
Next, we created clean up guides for sites affected by known hacks. We’ve noticed that sites often get affected in similar ways when hacked. By investigating the similarities, we were able to create clean up guides for specific known type of hack. Below is a short description of each of the guides we created:
Gibberish Hack: The gibberish hack automatically creates many pages with non-sensical sentences filled with keywords on the target site. Hackers do this so the hacked pages show up in Google Search. Then, when people try to visit these pages, they’ll be redirected to an unrelated page, like a porn site. Learn more on how to fix this type of hack.
Japanese Keywords Hack: The Japanese keywords hack typically creates new pages with Japanese text on the target site in randomly generated directory names. These pages are monetized using affiliate links to stores selling fake brand merchandise and then shown in Google search. Sometimes the accounts of the hackers get added in Search Console as site owners. Learn more on how to fix this type of hack.
Cloaked Keywords Hack: The cloaked keywords and link hack automatically creates many pages with non-sensical sentence, links, and images. These pages sometimes contain basic template elements from the original site, so at first glance, the pages might look like normal parts of the target site until you read the content. In this type of attack, hackers usually use cloaking techniques to hide the malicious content and make the injected page appear as part of the original site or a 404 error page. Learn more on how to fix this type of hack.

Prevention is Key


As always it’s best to take a preventative approach and secure your site rather than dealing with the aftermath. Remember a chain is only as strong as its weakest link. You can read more about how to identify vulnerabilities on your site in our hacked help guide. We also recommend staying up-to-date on releases and announcements from your Content Management System (CMS) providers and software/hardware vendors.

Looking Forward

Hacking behavior is constantly evolving, and research allows us to stay up to date on and combat the latest trends. You can learn about our latest research publications in the information security research site. Highlighted below are a few specific studies specific to website compromises:
If you have feedback or specific questions about compromised sites, the Webmaster Help Forums has an active group of Googlers and technical contributors that can address your questions and provide additional technical support.

Silence speaks louder than words when finding malware

Originally posted on Android Developer Blog

Posted by Megan Ruthven, Software Engineer

In Android Security, we're constantly working to better understand how to make Android devices operate more smoothly and securely. One security solution included on all devices with Google Play is Verify apps. Verify apps checks if there are Potentially Harmful Apps (PHAs) on your device. If a PHA is found, Verify apps warns the user and enables them to uninstall the app.

But, sometimes devices stop checking up with Verify apps. This may happen for a non-security related reason, like buying a new phone, or, it could mean something more concerning is going on. When a device stops checking up with Verify apps, it is considered Dead or Insecure (DOI). An app with a high enough percentage of DOI devices downloading it, is considered a DOI app. We use the DOI metric, along with the other security systems to help determine if an app is a PHA to protect Android users. Additionally, when we discover vulnerabilities, we patch Android devices with our security update system. This blog post explores the Android Security team's research to identify the security-related reasons that devices stop working and prevent it from happening in the future.
Flagging DOI Apps
To understand this problem more deeply, the Android Security team correlates app install attempts and DOI devices to find apps that harm the device in order to protect our users.
With these factors in mind, we then focus on 'retention'. A device is considered retained if it continues to perform periodic Verify apps security check ups after an app download. If it doesn't, it's considered potentially dead or insecure (DOI). An app's retention rate is the percentage of all retained devices that downloaded the app in one day. Because retention is a strong indicator of device health, we work to maximize the ecosystem's retention rate. Therefore, we use an app DOI scorer, which assumes that all apps should have a similar device retention rate. If an app's retention rate is a couple of standard deviations lower than average, the DOI scorer flags it. A common way to calculate the number of standard deviations from the average is called a Z-score. The equation for the Z-score is below.
  • N = Number of devices that downloaded the app.
  • x = Number of retained devices that downloaded the app.
  • p = Probability of a device downloading any app will be retained.

In this context, we call the Z-score of an app's retention rate a DOI score. The DOI score indicates an app has a statistically significant lower retention rate if the Z-score is much less than -3.7. This means that if the null hypothesis is true, there is much less than a 0.01% chance the magnitude of the Z-score being as high. In this case, the null hypothesis means the app accidentally correlated with lower retention rate independent of what the app does.
This allows for percolation of extreme apps (with low retention rate and high number of downloads) to the top of the DOI list. From there, we combine the DOI score with other information to determine whether to classify the app as a PHA. We then use Verify apps to remove existing installs of the app and prevent future installs of the app.
Difference between a regular and DOI app download on the same device.
Results in the wild
Among others, the DOI score flagged many apps in three well known malware families— Hummingbad, Ghost Push, and Gooligan. Although they behave differently, the DOI scorer flagged over 25,000 apps in these three families of malware because they can degrade the Android experience to such an extent that a non-negligible amount of users factory reset or abandon their devices. This approach provides us with another perspective to discover PHAs and block them before they gain popularity. Without the DOI scorer, many of these apps would have escaped the extra scrutiny of a manual review.
The DOI scorer and all of Android's anti-malware work is one of multiple layers protecting users and developers on Android. For an overview of Android's security and transparency efforts, check out our page.

Silence speaks louder than words when finding malware

Posted by Megan Ruthven, Software Engineer

In Android Security, we're constantly working to better understand how to make Android devices operate more smoothly and securely. One security solution included on all devices with Google Play is Verify apps. Verify apps checks if there are Potentially Harmful Apps (PHAs) on your device. If a PHA is found, Verify apps warns the user and enables them to uninstall the app.

But, sometimes devices stop checking up with Verify apps. This may happen for a non-security related reason, like buying a new phone, or, it could mean something more concerning is going on. When a device stops checking up with Verify apps, it is considered Dead or Insecure (DOI). An app with a high enough percentage of DOI devices downloading it, is considered a DOI app. We use the DOI metric, along with the other security systems to help determine if an app is a PHA to protect Android users. Additionally, when we discover vulnerabilities, we patch Android devices with our security update system.

This blog post explores the Android Security team's research to identify the security-related reasons that devices stop working and prevent it from happening in the future.
Flagging DOI Apps

To understand this problem more deeply, the Android Security team correlates app install attempts and DOI devices to find apps that harm the device in order to protect our users.
With these factors in mind, we then focus on 'retention'. A device is considered retained if it continues to perform periodic Verify apps security check ups after an app download. If it doesn't, it's considered potentially dead or insecure (DOI). An app's retention rate is the percentage of all retained devices that downloaded the app in one day. Because retention is a strong indicator of device health, we work to maximize the ecosystem's retention rate.

Therefore, we use an app DOI scorer, which assumes that all apps should have a similar device retention rate. If an app's retention rate is a couple of standard deviations lower than average, the DOI scorer flags it. A common way to calculate the number of standard deviations from the average is called a Z-score. The equation for the Z-score is below.

  • N = Number of devices that downloaded the app.
  • x = Number of retained devices that downloaded the app.
  • p = Probability of a device downloading any app will be retained.

In this context, we call the Z-score of an app's retention rate a DOI score. The DOI score indicates an app has a statistically significant lower retention rate if the Z-score is much less than -3.7. This means that if the null hypothesis is true, there is much less than a 0.01% chance the magnitude of the Z-score being as high. In this case, the null hypothesis means the app accidentally correlated with lower retention rate independent of what the app does.
This allows for percolation of extreme apps (with low retention rate and high number of downloads) to the top of the DOI list. From there, we combine the DOI score with other information to determine whether to classify the app as a PHA. We then use Verify apps to remove existing installs of the app and prevent future installs of the app.

Difference between a regular and DOI app download on the same device.


Results in the wild
Among others, the DOI score flagged many apps in three well known malware families— Hummingbad, Ghost Push, and Gooligan. Although they behave differently, the DOI scorer flagged over 25,000 apps in these three families of malware because they can degrade the Android experience to such an extent that a non-negligible amount of users factory reset or abandon their devices. This approach provides us with another perspective to discover PHAs and block them before they gain popularity. Without the DOI scorer, many of these apps would have escaped the extra scrutiny of a manual review.
The DOI scorer and all of Android's anti-malware work is one of multiple layers protecting users and developers on Android. For an overview of Android's security and transparency efforts, check out our page.


More Safe Browsing Help for Webmasters

(Crossposted from the Google Security Blog.)
For more than nine years, Safe Browsing has helped webmasters via Search Console with information about how to fix security issues with their sites. This includes relevant Help Center articles, example URLs to assist in diagnosing the presence of harmful content, and a process for webmasters to request reviews of their site after security issues are addressed. Over time, Safe Browsing has expanded its protection to cover additional threats to user safety such as Deceptive Sites and Unwanted Software.

To help webmasters be even more successful in resolving issues, we’re happy to announce that we’ve updated the information available in Search Console in the Security Issues report.


The updated information provides more specific explanations of six different security issues detected by Safe Browsing, including malware, deceptive pages, harmful downloads, and uncommon downloads. These explanations give webmasters more context and detail about what Safe Browsing found. We also offer tailored recommendations for each type of issue, including sample URLs that webmasters can check to identify the source of the issue, as well as specific remediation actions webmasters can take to resolve the issue.

We on the Safe Browsing team definitely recommend registering your site in Search Console even if it is not currently experiencing a security issue. We send notifications through Search Console so webmasters can address any issues that appear as quickly as possible.

Our goal is to help webmasters provide a safe and secure browsing experience for their users. We welcome any questions or feedback about the new features on the Google Webmaster Help Forum, where Top Contributors and Google employees are available to help.

For more information about Safe Browsing’s ongoing work to shine light on the state of web security and encourage safer web security practices, check out our summary of trends and findings on the Safe Browsing Transparency Report. If you’re interested in the tools Google provides for webmasters and developers dealing with hacked sites, this video provides a great overview.