As shared during the What's new in Android security session at Google I/O 2018, transparency and openness are important parts of Android's ethos. We regularly blog about new features and enhancements and publish an annual Android Security Year in Review , which highlights Android ecosystem trends. To provide more frequent insights, we're introducing a quarterly Android Ecosystem Security Transparency Report . This report is the latest addition to our Transparency Report site, which began in 2010 to show how the policies and actions of governments and corporations affect privacy, security, and access to information online.This Android Ecosystem Security Transparency Report covers how often a routine, full-device scan by Google Play Protect detects a device with PHAs installed. Google Play Protect is built-in protection on Android devices that scans over 50 billion apps daily from inside and outside of Google Play. These scans look for evidence of Potentially Harmful Applications (PHAs). If the scans find a PHA, Google Play Protect warns the user and can disable or remove PHAs. In Android's first annual Android Security Year in Review from 2014, fewer than 1% of devices had PHAs installed. The percentage has declined steadily over time and this downward trend continues through 2018. The transparency report covers PHA rates in three areas: market segment (whether a PHA came from Google Play or outside of Google Play), Android version, and country.Google works hard to protect your Android device: no matter where your apps come from. Continuing the trend from previous years, Android devices that only download apps from Google Play are 9 times less likely to get a PHA than devices that download apps from other sources. Before applications become available in Google Play they undergo an application review to confirm they comply with Google Play policies. Google uses a risk scorer to analyze apps to detect potentially harmful behavior. When Google’s application risk analyzer discovers something suspicious, it flags the app and refers the PHA to a security analyst for manual review if needed. We also scan apps that users download to their device from outside of Google Play. If we find a suspicious app, we also protect users from that—even if it didn't come from Google Play.In the Android Ecosystem Security Transparency Report, the Devices with Potentially Harmful Applications installed by market segment chart shows the percentage of Android devices that have one or more PHAs installed over time. The chart has two lines: PHA rate for devices that exclusively install from Google Play and PHA rate for devices that also install from outside of Google Play. In 2017, on average 0.09% of devices that exclusively used Google Play had one or more PHAs installed. The first three quarters in 2018 averaged a lower PHA rate of 0.08%.The security of devices that installed apps from outside of Google Play also improved. In 2017, ~0.82% of devices that installed apps from outside of Google Play were affected by PHA; in the first three quarters of 2018, ~0.68% were affected. Since 2017, we've reduced this number by expanding the auto-disable feature which we covered on page 10 in the 2017 Year in Review . While malware rates fluctuate from quarter to quarter, our metrics continue to show a consistent downward trend over time. We'll share more details in our 2018 Android Security Year in Review in early 2019.Newer versions of Android are less affected by PHAs. We attribute this to many factors, such as continued platform and API hardening, ongoing security updates and app security and developer training to reduce apps' access to sensitive data. In particular, newer Android versions—such as Nougat, Oreo, and Pie—are more resilient to privilege escalation attacks that had previously allowed PHAs to gain persistence on devices and protect themselves against removal attempts. The Devices with Potentially Harmful Applications installed by Android version chart shows the percentage of devices with a PHA installed, sorted by the Android version that the device is running.Overall, PHA rates in the ten largest Android markets have remained steady. While these numbers fluctuate on a quarterly basis due to the fluidity of the marketplace, we intend to provide more in depth coverage of what drove these changes in our annual Year in Review in Q1, 2019.Thechart shows the percentage of devices with at least one PHA in the ten countries with the highest volume of Android devices. India saw the most significant decline in PHAs present on devices, with the average rate of infection dropping by 34 percent. Indonesia, Mexico, and Turkey also saw a decline in the likelihood of PHAs being present on devices in the region. South Korea saw the lowest number of devices containing PHA, with only 0.1%.Over time, we'll add more insights into the health of the ecosystem to the Android Ecosystem Security Transparency Report . If you have any questions about terminology or the products referred to in this report please review the FAQs section of the Transparency Report . In the meantime, check out our new blog post and video outlining Android’s performance in Gartner’s Mobile OSs and Device Security: A Comparison of Platforms report.