Android users who download from Google Play are less likely to install potentially harmful apps than those who download from unofficial third-party stores, according to the inaugural edition of Google's quarterly Android Ecosystem Security Transparency Report.

The data published in the online report last Thursday was collected from users who enabled the Google Play Protect anti-mobile malware service that Google introduced last year.

Between March 31, 2017 and Sept. 30, 2018, only 0.05% to 0.11% of these users were infected with at least one potentially harmful app (PHA), provided they only downloaded their apps from the Google Play store.

However, 0.65% to 0.91% users were infected with at least one PHA if they ventured into uncharted waters and downloaded apps from third-party sources outside of Google's purview.

During the time period in question, users running the most recent Android OS release, Pie (9.0), had the smallest rate of PHA infection among all Android devices -- a mere 0.06% -- followed by Oreo, Nougat, Marshmallow, KitKat and Lollipop.

With the notable exception of Lollipop, each newer version of Android was found to be less affected than the previous one. "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," states a Google blog post authored by Jason Woloz, head of Android's anti-malware program, and Eugene Liderman, director of Google's mobile security strategy. "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."

Geographically, users in Indonesia and India generally had the highest shares of devices infected by PHAs during the aforementioned time period (although India's numbers were notably down from previous studies). The other countries in the top 10 were the U.S., Russia, Mexico, Brazil, Turkey, Germany, South Korea and Japan.